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The markdown parsing is broken/disabled for release notes. Sorry about that, I'm chasing the source of a crash that's been bringing this website down for the last couple of days. This release highlights the deployment of Google [Chrome 123](https://developer.chrome.com/blog/new-in-chrome-123), introducing `zstd-encoding` for Web traffic, introduced as a preferable option for compression of dynamic contents. With limited web server support for `zstd-encoding` due to its novelty, we are launching an updated Zstandard version to facilitate broader adoption. ### New stable parameter `ZSTD_c_targetCBlockSize` Using `zstd` compression for large documents over the Internet, data is segmented into smaller blocks of up to 128 KB, for incremental updates. This is crucial for applications like Chrome that process parts of documents as they arrive. However, on slow or congested networks, there can be some brief unresponsiveness in the middle of a block transmission, delaying update. To mitigate such scenarios, `libzstd` introduces the new parameter `ZSTD_c_targetCBlockSize`, enabling the division of blocks into even smaller segments to enhance initial byte delivery speed. Activating this feature incurs a cost, both runtime (equivalent to -2% speed at level 8) and a slight compression efficiency decrease (<0.1%), but offers some interesting latency reduction, notably beneficial in areas with less powerful network infrastructure. ### Granular binary size selection `libzstd` provides build customization, including options to compile only the compression or decompression modules, minimizing binary size. Enhanced in `v1.5.6` ([source](https://github.com/facebook/zstd/tree/dev/lib#modular-build)), it now allows for even finer control by enabling selective inclusion or exclusion of specific components within these modules. This advancement aids applications needing precise binary size management. ### Miscellaneous Enhancements This release includes various minor enhancements and bug fixes to enhance user experience. Key updates include an expanded list of recognized compressed file suffixes for the `--exclude-compressed` flag, improving efficiency by skipping presumed incompressible content. Furthermore, compatibility has been broadened to include additional chipsets (`sparc64`, `ARM64EC`, `risc-v`) and operating systems (`QNX`, `AIX`, `Solaris`, `HP-UX`). ## Change Log api: Promote `ZSTD_c_targetCBlockSize` to Stable API by @felixhandte api: new experimental `ZSTD_d_maxBlockSize` parameter, to reduce streaming decompression memory, by @terrelln perf: improve performance of param `ZSTD_c_targetCBlockSize`, by @Cyan4973 perf: improved compression of arrays of integers at high compression, by @Cyan4973 lib: reduce binary size with selective built-time exclusion, by @felixhandte lib: improved huffman speed on small data and linux kernel, by @terrelln lib: accept dictionaries with partial literal tables, by @terrelln lib: fix CCtx size estimation with external sequence producer, by @embg lib: fix corner case decoder behaviors, by @Cyan4973 and @aimuz lib: fix zdict prototype mismatch in static_only mode, by @ldv-alt lib: fix several bugs in magicless-format decoding, by @embg cli: add common compressed file types to `--exclude-compressed` by @daniellerozenblit (requested by @dcog989) cli: fix mixing `-c` and `-o` commands with `--rm`, by @Cyan4973 cli: fix erroneous exclusion of hidden files with `--output-dir-mirror` by @felixhandte cli: improved time accuracy on BSD, by @felixhandte cli: better errors on argument parsing, by @KapJI tests: better compatibility with older versions of `grep`, by @Cyan4973 tests: lorem ipsum generator as default content generator, by @Cyan4973 build: cmake improvements by @terrelln, @sighingnow, @gjasny, @JohanMabille, @Saverio976, @gruenich, @teo-tsirpanis build: bazel support, by @jondo2010 build: fix cross-compiling for AArch64 with lld by @jcelerier build: fix Apple platform compatibility, by @nidhijaju build: fix Visual 2012 and lower compatibility, by @Cyan4973 build: improve win32 support, by @DimitriPapadopoulos build: better C90 compliance for zlibWrapper, by @emaste port: make: fat binaries on macos, by @mredig port: ARM64EC compatibility for Windows, by @dunhor port: QNX support by @klausholstjacobsen port: MSYS2 and Cygwin makefile installation and test support, by @QBos07 port: risc-v support validation in CI, by @Cyan4973 port: sparc64 support validation in CI, by @Cyan4973 port: AIX compatibility, by @likema port: HP-UX compatibility, by @likema doc: Improved specification accuracy, by @elasota bug: Fix and deprecate ZSTD_generateSequences (#3981), by @terrelln ## Full change list (auto-generated) * Add win32 to windows-artifacts.yml by @Kim-SSi in https://github.com/facebook/zstd/pull/3600 * Fix mmap-dict help output by @daniellerozenblit in https://github.com/facebook/zstd/pull/3601 * [oss-fuzz] Fix simple_round_trip fuzzer with overlapping decompression by @terrelln in https://github.com/facebook/zstd/pull/3612 * Reduce streaming decompression memory by (128KB - blockSizeMax) by @terrelln in https://github.com/facebook/zstd/pull/3616 * removed travis & appveyor scripts by @Cyan4973 in https://github.com/facebook/zstd/pull/3621 * Add ZSTD_d_maxBlockSize parameter by @terrelln in https://github.com/facebook/zstd/pull/3617 * [doc] add decoder errata paragraph by @Cyan4973 in https://github.com/facebook/zstd/pull/3620 * add makefile entry to build fat binary on macos by @mredig in https://github.com/facebook/zstd/pull/3614 * Disable unused variable warning in msan configurations by @danlark1 in https://github.com/facebook/zstd/pull/3624 https://github.com/facebook/zstd/pull/3634 * Allow Build-Time Exclusion of Individual Compression Strategies by @felixhandte in https://github.com/facebook/zstd/pull/3623 * Get zstd working with ARM64EC on Windows by @dunhor in https://github.com/facebook/zstd/pull/3636 * minor : update streaming_compression example by @Cyan4973 in https://github.com/facebook/zstd/pull/3631 * Fix UBSAN issue (zero addition to NULL) by @terrelln in https://github.com/facebook/zstd/pull/3658 * Add options in Makefile to cmake by @sighingnow in https://github.com/facebook/zstd/pull/3657 * fix a minor inefficiency in compress_superblock by @Cyan4973 in https://github.com/facebook/zstd/pull/3668 * Fixed a bug in the educational decoder by @Cyan4973 in https://github.com/facebook/zstd/pull/3659 * changed LLU suffix into ULL for Visual 2012 and lower by @Cyan4973 in https://github.com/facebook/zstd/pull/3664 * fixed decoder behavior when nbSeqs==0 is encoded using 2 bytes by @Cyan4973 in https://github.com/facebook/zstd/pull/3669 * detect extraneous bytes in the Sequences section by @Cyan4973 in https://github.com/facebook/zstd/pull/3674 * Bitstream produces only zeroes after an overflow event by @Cyan4973 in https://github.com/facebook/zstd/pull/3676 * Update FreeBSD CI images to latest supported releases by @emaste in https://github.com/facebook/zstd/pull/3684 * Clean up a false error message in the LDM debug log by @embg in https://github.com/facebook/zstd/pull/3686 * Hide ASM symbols on Apple platforms by @nidhijaju in https://github.com/facebook/zstd/pull/3688 * Changed the decoding loop to detect more invalid cases of corruption sooner by @Cyan4973 in https://github.com/facebook/zstd/pull/3677 * Fix Intel Xcode builds with assembly by @gjasny in https://github.com/facebook/zstd/pull/3665 * Save one byte on the frame epilogue by @Coder-256 in https://github.com/facebook/zstd/pull/3700 * Update fileio.c: fix build failure with enabled LTO by @LocutusOfBorg in https://github.com/facebook/zstd/pull/3695 * fileio_asyncio: handle malloc fails in AIO_ReadPool_create by @void0red in https://github.com/facebook/zstd/pull/3704 * Fix typographical error in README.md by @nikohoffren in https://github.com/facebook/zstd/pull/3701 * Fixed typo by @alexsifivetw in https://github.com/facebook/zstd/pull/3712 * Improve dual license wording in README by @terrelln in https://github.com/facebook/zstd/pull/3718 * Unpoison Workspace Memory Before Custom-Free by @felixhandte in https://github.com/facebook/zstd/pull/3725 * added ZSTD_decompressDCtx() benchmark option to fullbench by @Cyan4973 in https://github.com/facebook/zstd/pull/3726 * No longer reject dictionaries with literals maxSymbolValue < 255 by @terrelln in https://github.com/facebook/zstd/pull/3731 * fix: ZSTD_BUILD_DECOMPRESSION message by @0o001 in https://github.com/facebook/zstd/pull/3728 * Updated Makefiles for full MSYS2 and Cygwin installation and testing … by @QBos07 in https://github.com/facebook/zstd/pull/3720 * Work around nullptr-with-nonzero-offset warning by @terrelln in https://github.com/facebook/zstd/pull/3738 * Fix & refactor Huffman repeat tables for dictionaries by @terrelln in https://github.com/facebook/zstd/pull/3737 * zdictlib: fix prototype mismatch by @ldv-alt in https://github.com/facebook/zstd/pull/3733 * Fixed zstd cmake shared build on windows by @JohanMabille in https://github.com/facebook/zstd/pull/3739 * Added qnx in the posix test section of platform.h by @klausholstjacobsen in https://github.com/facebook/zstd/pull/3745 * added some documentation on ZSTD_estimate*Size() variants by @Cyan4973 in https://github.com/facebook/zstd/pull/3755 * Improve macro guards for ZSTD_assertValidSequence by @terrelln in https://github.com/facebook/zstd/pull/3770 * Stop suppressing pointer-overflow UBSAN errors by @terrelln in https://github.com/facebook/zstd/pull/3776 * fix x32 tests on Github CI by @Cyan4973 in https://github.com/facebook/zstd/pull/3777 * Fix new typos found by codespell by @DimitriPapadopoulos in https://github.com/facebook/zstd/pull/3771 * Do not test WIN32, instead test _WIN32 by @DimitriPapadopoulos in https://github.com/facebook/zstd/pull/3772 * Fix a very small formatting typo in the lib/README.md file by @dloidolt in https://github.com/facebook/zstd/pull/3763 * Fix pzstd Makefile to allow setting `DESTDIR` and `BINDIR` separately by @paulmenzel in https://github.com/facebook/zstd/pull/3752 * Remove FlexArray pattern from ZSTDMT by @Cyan4973 in https://github.com/facebook/zstd/pull/3786 * solving flexArray issue #3785 in fse by @Cyan4973 in https://github.com/facebook/zstd/pull/3789 * Add doc on how to use it with cmake FetchContent by @Saverio976 in https://github.com/facebook/zstd/pull/3795 * Correct FSE probability bit consumption in specification by @elasota in https://github.com/facebook/zstd/pull/3806 * Add Bazel module instructions to README.md by @jondo2010 in https://github.com/facebook/zstd/pull/3812 * Clarify that a stream containing too many Huffman weights is invalid by @elasota in https://github.com/facebook/zstd/pull/3813 * [cmake] Require CMake version 3.5 or newer by @gruenich in https://github.com/facebook/zstd/pull/3807 * Three fixes for the Linux kernel by @terrelln in https://github.com/facebook/zstd/pull/3822 * [huf] Improve fast huffman decoding speed in linux kernel by @terrelln in https://github.com/facebook/zstd/pull/3826 * [huf] Improve fast C & ASM performance on small data by @terrelln in https://github.com/facebook/zstd/pull/3827 * update xxhash library to v0.8.2 by @Cyan4973 in https://github.com/facebook/zstd/pull/3820 * Modernize macros to use `do { } while (0)` by @terrelln in https://github.com/facebook/zstd/pull/3831 * Clarify that the presence of weight value 1 is required, and a lone implied 1 weight is invalid by @elasota in https://github.com/facebook/zstd/pull/3814 * Move offload API params into ZSTD_CCtx_params by @embg in https://github.com/facebook/zstd/pull/3839 * Update FreeBSD CI: drop 12.4 (nearly EOL) by @emaste in https://github.com/facebook/zstd/pull/3845 * Make offload API compatible with static CCtx by @embg in https://github.com/facebook/zstd/pull/3854 * zlibWrapper: convert to C89 / ANSI C by @emaste in https://github.com/facebook/zstd/pull/3846 * Fix a nullptr dereference in ZSTD_createCDict_advanced2() by @michoecho in https://github.com/facebook/zstd/pull/3847 * Cirrus-CI: Add FreeBSD 14 by @emaste in https://github.com/facebook/zstd/pull/3855 * CI: meson: use builtin handling for MSVC by @eli-schwartz in https://github.com/facebook/zstd/pull/3858 * cli: better errors on argument parsing by @KapJI in https://github.com/facebook/zstd/pull/3850 * Clarify that probability tables must not contain non-zero probabilities for invalid values by @elasota in https://github.com/facebook/zstd/pull/3817 * [x-compile] Fix cross-compiling for AArch64 with lld by @jcelerier in https://github.com/facebook/zstd/pull/3760 * playTests.sh does no longer needs grep -E by @Cyan4973 in https://github.com/facebook/zstd/pull/3865 * minor: playTests.sh more compatible with older versions of grep by @Cyan4973 in https://github.com/facebook/zstd/pull/3877 * disable Intel CET Compatibility tests by @Cyan4973 in https://github.com/facebook/zstd/pull/3884 * improve cmake test by @Cyan4973 in https://github.com/facebook/zstd/pull/3883 * add sparc64 compilation test by @Cyan4973 in https://github.com/facebook/zstd/pull/3886 * add a lorem ipsum generator by @Cyan4973 in https://github.com/facebook/zstd/pull/3890 * Update Dependency in Intel CET Test; Re-Enable Test by @felixhandte in https://github.com/facebook/zstd/pull/3893 * Improve compression of Arrays of Integers (High compression mode) by @Cyan4973 in https://github.com/facebook/zstd/pull/3895 * [Zstd] Less verbose log for patch mode. by @sandreenko in https://github.com/facebook/zstd/pull/3899 * fix 5921623844651008 by @Cyan4973 in https://github.com/facebook/zstd/pull/3900 * Fix fuzz issue 5131069967892480 by @Cyan4973 in https://github.com/facebook/zstd/pull/3902 * Advertise Availability of Security Vulnerability Notifications by @felixhandte in https://github.com/facebook/zstd/pull/3909 * updated setup-msys2 to v2.22.0 by @Cyan4973 in https://github.com/facebook/zstd/pull/3914 * Lorem Ipsum generator update by @Cyan4973 in https://github.com/facebook/zstd/pull/3913 * Reduce scope of variables by @gruenich in https://github.com/facebook/zstd/pull/3903 * Improve speed of ZSTD_c_targetCBlockSize by @Cyan4973 in https://github.com/facebook/zstd/pull/3915 * More regular block sizes with `targetCBlockSize` by @Cyan4973 in https://github.com/facebook/zstd/pull/3917 * removed sprintf usage from zstdcli.c by @Cyan4973 in https://github.com/facebook/zstd/pull/3916 * Export a `zstd::libzstd` CMake target if only static or dynamic linkage is specified. by @teo-tsirpanis in https://github.com/facebook/zstd/pull/3811 * fix version of actions/checkout by @Cyan4973 in https://github.com/facebook/zstd/pull/3926 * minor Makefile refactoring by @Cyan4973 in https://github.com/facebook/zstd/pull/3753 * lib/decompress: check for reserved bit corruption in zstd by @aimuz in https://github.com/facebook/zstd/pull/3840 * Fix state table formatting by @elasota in https://github.com/facebook/zstd/pull/3816 * Specify offset 0 as invalid and specify required fixup behavior by @elasota in https://github.com/facebook/zstd/pull/3824 * update -V documentation by @Cyan4973 in https://github.com/facebook/zstd/pull/3928 * fix LLU->ULL by @Cyan4973 in https://github.com/facebook/zstd/pull/3929 * Fix building xxhash on AIX 5.1 by @likema in https://github.com/facebook/zstd/pull/3860 * Fix building on HP-UX 11.11 PA-RISC by @likema in https://github.com/facebook/zstd/pull/3862 * Fix AsyncIO reading seed queueing by @yoniko in https://github.com/facebook/zstd/pull/3940 * Use ZSTD_LEGACY_SUPPORT=5 in "make test" by @embg in https://github.com/facebook/zstd/pull/3943 * Pin sanitizer CI jobs to ubuntu-20.04 by @embg in https://github.com/facebook/zstd/pull/3945 * chore: fix some typos by @acceptacross in https://github.com/facebook/zstd/pull/3949 * new method to deal with offset==0 erroneous edge case by @Cyan4973 in https://github.com/facebook/zstd/pull/3937 * add tests inspired from #2927 by @Cyan4973 in https://github.com/facebook/zstd/pull/3948 * cmake refactor: move HP-UX specific logic into its own function by @Cyan4973 in https://github.com/facebook/zstd/pull/3946 * Fix #3719 : mixing -c, -o and --rm by @Cyan4973 in https://github.com/facebook/zstd/pull/3942 * minor: fix incorrect debug level by @Cyan4973 in https://github.com/facebook/zstd/pull/3936 * add RISC-V emulation tests to Github CI by @Cyan4973 in https://github.com/facebook/zstd/pull/3934 * prevent XXH64 from being autovectorized by XXH512 by default by @Cyan4973 in https://github.com/facebook/zstd/pull/3933 * Stop Hardcoding the POSIX Version on BSDs by @felixhandte in https://github.com/facebook/zstd/pull/3952 * Convert the CircleCI workflow to a GitHub Actions workflow by @jk0 in https://github.com/facebook/zstd/pull/3901 * Add common compressed file types to --exclude-compressed by @daniellerozenblit in https://github.com/facebook/zstd/pull/3951 * Export ZSTD_LEGACY_SUPPORT in tests/Makefile by @embg in https://github.com/facebook/zstd/pull/3955 * Exercise ZSTD_findDecompressedSize() in the simple decompression fuzzer by @embg in https://github.com/facebook/zstd/pull/3959 * Update `ZSTD_RowFindBestMatch` comment by @yoniko in https://github.com/facebook/zstd/pull/3947 * Add the zeroSeq sample by @Cyan4973 in https://github.com/facebook/zstd/pull/3954 * [cpu] Backport fix for rbx clobbering on Windows with Clang by @terrelln in https://github.com/facebook/zstd/pull/3957 * Do not truncate file name in verbose mode by @Cyan4973 in https://github.com/facebook/zstd/pull/3956 * updated documentation by @Cyan4973 in https://github.com/facebook/zstd/pull/3958 * [asm][aarch64] Mark that BTI and PAC are supported by @terrelln in https://github.com/facebook/zstd/pull/3961 * Use `utimensat()` on FreeBSD by @felixhandte in https://github.com/facebook/zstd/pull/3960 * reduce the amount of #include in cover.h by @Cyan4973 in https://github.com/facebook/zstd/pull/3962 * Remove Erroneous Exclusion of Hidden Files and Folders in `--output-dir-mirror` by @felixhandte in https://github.com/facebook/zstd/pull/3963 * Promote `ZSTD_c_targetCBlockSize` Parameter to Stable API by @felixhandte in https://github.com/facebook/zstd/pull/3964 * [cmake] Always create libzstd target by @terrelln in https://github.com/facebook/zstd/pull/3965 * Remove incorrect docs regarding ZSTD_findFrameCompressedSize() by @embg in https://github.com/facebook/zstd/pull/3967 * add line number to debug traces by @Cyan4973 in https://github.com/facebook/zstd/pull/3966 * bump version number by @Cyan4973 in https://github.com/facebook/zstd/pull/3969 * Export zstd's public headers via BUILD_INTERFACE by @terrelln in https://github.com/facebook/zstd/pull/3968 * Fix bug with streaming decompression of magicless format by @embg in https://github.com/facebook/zstd/pull/3971 * pzstd: use c++14 without conditions by @kanavin in https://github.com/facebook/zstd/pull/3682 * Fix bugs in simple decompression fuzzer by @yoniko in https://github.com/facebook/zstd/pull/3978 * Fuzzing and bugfixes for magicless-format decoding by @embg in https://github.com/facebook/zstd/pull/3976 * Fix & fuzz ZSTD_generateSequences by @terrelln in https://github.com/facebook/zstd/pull/3981 * Fail on errors when building fuzzers by @yoniko in https://github.com/facebook/zstd/pull/3979 * [cmake] Emit warnings for contradictory build settings by @terrelln in https://github.com/facebook/zstd/pull/3975 * Document the process for adding a new fuzzer by @embg in https://github.com/facebook/zstd/pull/3982 * Fix -Werror=pointer-arith in fuzzers by @embg in https://github.com/facebook/zstd/pull/3983 * Doc update by @Cyan4973 in https://github.com/facebook/zstd/pull/3977 * v1.5.6 by @Cyan4973 in https://github.com/facebook/zstd/pull/3984 ## New Contributors * @Kim-SSi made their first contribution in https://github.com/facebook/zstd/pull/3600 * @mredig made their first contribution in https://github.com/facebook/zstd/pull/3614 * @dunhor made their first contribution in https://github.com/facebook/zstd/pull/3636 * @sighingnow made their first contribution in https://github.com/facebook/zstd/pull/3657 * @nidhijaju made their first contribution in https://github.com/facebook/zstd/pull/3688 * @gjasny made their first contribution in https://github.com/facebook/zstd/pull/3665 * @Coder-256 made their first contribution in https://github.com/facebook/zstd/pull/3700 * @LocutusOfBorg made their first contribution in https://github.com/facebook/zstd/pull/3695 * @void0red made their first contribution in https://github.com/facebook/zstd/pull/3704 * @nikohoffren made their first contribution in https://github.com/facebook/zstd/pull/3701 * @alexsifivetw made their first contribution in https://github.com/facebook/zstd/pull/3712 * @0o001 made their first contribution in https://github.com/facebook/zstd/pull/3728 * @QBos07 made their first contribution in https://github.com/facebook/zstd/pull/3720 * @JohanMabille made their first contribution in https://github.com/facebook/zstd/pull/3739 * @klausholstjacobsen made their first contribution in https://github.com/facebook/zstd/pull/3745 * @Saverio976 made their first contribution in https://github.com/facebook/zstd/pull/3795 * @elasota made their first contribution in https://github.com/facebook/zstd/pull/3806 * @jondo2010 made their first contribution in https://github.com/facebook/zstd/pull/3812 * @gruenich made their first contribution in https://github.com/facebook/zstd/pull/3807 * @michoecho made their first contribution in https://github.com/facebook/zstd/pull/3847 * @KapJI made their first contribution in https://github.com/facebook/zstd/pull/3850 * @jcelerier made their first contribution in https://github.com/facebook/zstd/pull/3760 * @sandreenko made their first contribution in https://github.com/facebook/zstd/pull/3899 * @teo-tsirpanis made their first contribution in https://github.com/facebook/zstd/pull/3811 * @aimuz made their first contribution in https://github.com/facebook/zstd/pull/3840 * @acceptacross made their first contribution in https://github.com/facebook/zstd/pull/3949 * @jk0 made their first contribution in https://github.com/facebook/zstd/pull/3901 **Full Changelog**: https://github.com/facebook/zstd/compare/v1.5.5...v1.5.6 This is a quick fix release. The primary focus is to correct a rare corruption bug in high compression mode, detected by @danlark1 . The probability to generate such a scenario by random chance is extremely low. It evaded months of continuous fuzzer tests, due to the number and complexity of simultaneous conditions required to trigger it. Nevertheless, @danlark1 from Google shepherds such a humongous amount of data that he managed to detect a reproduction case (corruptions are detected thanks to the checksum), making it possible for @terrelln to investigate and fix the bug. Thanks ! While the probability might be very small, corruption issues are nonetheless very serious, so an update to this version is highly recommended, especially if you employ high compression modes (levels 16+). When the issue was detected, there were a number of other improvements and minor fixes already in the making, hence they are also present in this release. Let’s detail the main ones. ### Improved memory usage and speed for the `--patch-from` mode `V1.5.5` introduces memory-mapped dictionaries, by @daniellerozenblit, for both posix [#3486](https://github.com/facebook/zstd/pull/3486) and windows [#3557](https://github.com/facebook/zstd/pull/3557). This feature allows `zstd` to memory-map large dictionaries, rather than requiring to load them into memory. This can make a pretty big difference for memory-constrained environments operating patches for large data sets. It's mostly visible under memory pressure, since `mmap` will be able to release less-used memory and continue working. But even when memory is plentiful, there are still measurable memory benefits, as shown in the graph below, especially when the reference turns out to be not completely relevant for the patch.  This feature is automatically enabled for `--patch-from` compression/decompression when the dictionary is larger than the user-set memory limit. It can also be manually enabled/disabled using `--mmap-dict` or `--no-mmap-dict` respectively. Additionally, @daniellerozenblit introduces significant speed improvements for `--patch-from`. An `I/O` optimization in [#3486](https://github.com/facebook/zstd/pull/3486) greatly improves `--patch-from` decompression speed on Linux, typically by `+50%` on large files (~1GB).  Compression speed is also taken care of, with a dictionary-indexing speed optimization introduced in [#3545](https://github.com/facebook/zstd/pull/3545). It wildly accelerates `--patch-from` compression, typically doubling speed on large files (~1GB), sometimes even more depending on exact scenario.  This speed improvement comes at a slight regression in compression ratio, and is therefore enabled only on non-ultra compression strategies. ### Speed improvements of middle-level compression for specific scenarios The row-hash match finder introduced in version 1.5.0 for levels 5-12 has been improved in version 1.5.5, enhancing its speed in specific corner-case scenarios. The first optimization ([#3426](https://github.com/facebook/zstd/pull/3426)) accelerates streaming compression using `ZSTD_compressStream` on small inputs by removing an expensive table initialization step. This results in remarkable speed increases for very small inputs. The following scenario measures compression speed of `ZSTD_compressStream` at level 9 for different sample sizes on a linux platform running an i7-9700k cpu. | sample size | `v1.5.4` (MB/s) | `v1.5.5` (MB/s) | improvement | | --- | ----:| ---:| --- | | 100 | 1.4 | 44.8 | x32 | 200 | 2.8 | 44.9 | x16 | 500 | 6.5 | 60.0 | x9.2 | 1K | 12.4 | 70.0 | x5.6 | 2K | 25.0 | 111.3 | x4.4 | 4K | 44.4 | 139.4 | x3.2 | ... | ... | ... | | 1M | 97.5 | 99.4 | +2% The second optimization ([#3552](https://github.com/facebook/zstd/issues/3552)) speeds up compression of incompressible data by a large multiplier. This is achieved by increasing the step size and reducing the frequency of matching when no matches are found, with negligible impact on the compression ratio. It makes mid-level compression essentially inexpensive when processing incompressible data, typically, already compressed data (note: this was already the case for fast compression levels). The following scenario measures compression speed of `ZSTD_compress` compiled with `gcc-9` for a ~10MB incompressible sample on a linux platform running an i7-9700k cpu. | level | `v1.5.4` (MB/s) | `v1.5.5` (MB/s) | improvement | | --- | ----:| ---:| --- | | 3 | 3500 | 3500 | not a row-hash level (control) | 5 | 400 | 2500 | x6.2 | 7 | 380 | 2200 | x5.8 | 9 | 176 | 1880 | x10 | 11 | 67 | 1130 | x16 | 13 | 89 | 89 | not a row-hash level (control) ### Miscellaneous There are other welcome speed improvements in this package. For example, @felixhandte managed to increase processing speed of small files by carefully reducing the nb of system calls (#3479). This can easily translate into +10% speed when processing a lot of small files in batch. The Seekable format received a bit of care. It's now much faster when splitting data into very small blocks (#3544). In an extreme scenario reported by @P-E-Meunier, it improves processing speed by x90. Even for more "common" settings, such as using 4KB blocks on some "normally" compressible data like `enwik`, it still provides a healthy x2 processing speed benefit. Moreover, @dloidolt merged an optimization that reduces the nb of `I/O` `seek()` events during reads (decompression), which is also beneficial for speed. The release is not limited to speed improvements, several loose ends and corner cases were also fixed in this release. For a more detailed list of changes, please take a look at the changelog. ## Change Log - fix: fix rare corruption bug affecting the high compression mode, reported by @danlark1 (#3517, @terrelln) - perf: improve mid-level compression speed (#3529, #3533, #3543, @yoniko and #3552, @terrelln) - lib: deprecated bufferless block-level API (#3534) by @terrelln - cli: `mmap` large dictionaries to save memory, by @daniellerozenblit - cli: improve speed of `--patch-from` mode (~+50%) (#3545) by @daniellerozenblit - cli: improve i/o speed (~+10%) when processing lots of small files (#3479) by @felixhandte - cli: `zstd` no longer crashes when requested to write into write-protected directory (#3541) by @felixhandte - cli: fix decompression into block device using `-o` (#3584, @Cyan4973) reported by @georgmu - build: fix zstd CLI compiled with lzma support but not zlib support (#3494) by @Hello71 - build: fix `cmake` does no longer require 3.18 as minimum version (#3510) by @kou - build: fix MSVC+ClangCL linking issue (#3569) by @tru - build: fix zstd-dll, version of zstd CLI that links to the dynamic library (#3496) by @yoniko - build: fix MSVC warnings (#3495) by @embg - doc: updated zstd specification to clarify corner cases, by @Cyan4973 - doc: document how to create fat binaries for macos (#3568) by @rickmark - misc: improve seekable format ingestion speed (~+100%) for very small chunk sizes (#3544) by @Cyan4973 - misc: `tests/fullbench` can benchmark multiple files (#3516) by @dloidolt ## Full change list (auto-generated) * Fix all MSVC warnings by @embg in https://github.com/facebook/zstd/pull/3495 * Fix zstd-dll build missing dependencies by @yoniko in https://github.com/facebook/zstd/pull/3496 * Bump github/codeql-action from 2.2.1 to 2.2.4 by @dependabot in https://github.com/facebook/zstd/pull/3503 * Github Action to generate Win64 artifacts by @Cyan4973 in https://github.com/facebook/zstd/pull/3491 * Use correct types in LZMA comp/decomp by @Hello71 in https://github.com/facebook/zstd/pull/3497 * Make Github workflows permissions read-only by default by @yoniko in https://github.com/facebook/zstd/pull/3488 * CI Workflow for external compressors dependencies by @yoniko in https://github.com/facebook/zstd/pull/3505 * Fix cli-tests issues by @daniellerozenblit in https://github.com/facebook/zstd/pull/3509 * Fix Permissions on Publish Release Artifacts Job by @felixhandte in https://github.com/facebook/zstd/pull/3511 * Use `f`-variants of `chmod()` and `chown()` by @felixhandte in https://github.com/facebook/zstd/pull/3479 * Don't require CMake 3.18 or later by @kou in https://github.com/facebook/zstd/pull/3510 * meson: always build the zstd binary when tests are enabled by @eli-schwartz in https://github.com/facebook/zstd/pull/3490 * [bug-fix] Fix rare corruption bug affecting the block splitter by @terrelln in https://github.com/facebook/zstd/pull/3517 * Clarify zstd specification for Huffman blocks by @Cyan4973 in https://github.com/facebook/zstd/pull/3514 * Fix typos found by codespell by @DimitriPapadopoulos in https://github.com/facebook/zstd/pull/3513 * Bump github/codeql-action from 2.2.4 to 2.2.5 by @dependabot in https://github.com/facebook/zstd/pull/3518 * fullbench with two files by @dloidolt in https://github.com/facebook/zstd/pull/3516 * Add initialization of clevel to static cdict (#3525) by @yoniko in https://github.com/facebook/zstd/pull/3527 * [linux-kernel] Fix assert definition by @terrelln in https://github.com/facebook/zstd/pull/3532 * Add ZSTD_set{C,F,}Params() helper functions by @terrelln in https://github.com/facebook/zstd/pull/3530 * Clarify dstCapacity requirements by @terrelln in https://github.com/facebook/zstd/pull/3531 * Mmap large dictionaries in patch-from mode by @daniellerozenblit in https://github.com/facebook/zstd/pull/3486 * added clarifications for sizes of compressed huffman blocks and streams. by @Cyan4973 in https://github.com/facebook/zstd/pull/3538 * Simplify benchmark unit invocation API from CLI by @Cyan4973 in https://github.com/facebook/zstd/pull/3526 * Avoid Segfault Caused by Calling `setvbuf()` on Null File Pointer by @felixhandte in https://github.com/facebook/zstd/pull/3541 * Pin Moar Action Dependencies by @felixhandte in https://github.com/facebook/zstd/pull/3542 * Improved seekable format ingestion speed for small frame size by @Cyan4973 in https://github.com/facebook/zstd/pull/3544 * Reduce RowHash's tag space size by x2 by @yoniko in https://github.com/facebook/zstd/pull/3543 * [Bugfix] row hash tries to match position 0 by @yoniko in https://github.com/facebook/zstd/pull/3548 * Bump github/codeql-action from 2.2.5 to 2.2.6 by @dependabot in https://github.com/facebook/zstd/pull/3549 * Add init once memory (#3528) by @yoniko in https://github.com/facebook/zstd/pull/3529 * Introduce salt into row hash (#3528 part 2) by @yoniko in https://github.com/facebook/zstd/pull/3533 * added documentation for the seekable format by @Cyan4973 in https://github.com/facebook/zstd/pull/3547 * patch-from speed optimization by @daniellerozenblit in https://github.com/facebook/zstd/pull/3545 * Deprecated bufferless and block level APIs by @terrelln in https://github.com/facebook/zstd/pull/3534 * added documentation for LDM + dictionary compatibility by @Cyan4973 in https://github.com/facebook/zstd/pull/3553 * Fix a bug in the CLI tests newline processing, then simplify it further by @ppentchev in https://github.com/facebook/zstd/pull/3559 * [lazy] Skip over incompressible data by @terrelln in https://github.com/facebook/zstd/pull/3552 * Fix patch-from speed optimization by @daniellerozenblit in https://github.com/facebook/zstd/pull/3556 * Bump actions/checkout from 3.3.0 to 3.5.0 by @dependabot in https://github.com/facebook/zstd/pull/3572 * [easy] minor doc update for --rsyncable by @Cyan4973 in https://github.com/facebook/zstd/pull/3570 * [contrib/pzstd] Select `-std=c++11` When Default is Older by @felixhandte in https://github.com/facebook/zstd/pull/3574 * Add instructions for building Universal2 on macOS via CMake by @rickmark in https://github.com/facebook/zstd/pull/3568 * Provide an interface for fuzzing sequence producer plugins by @embg in https://github.com/facebook/zstd/pull/3551 * mmap for windows by @daniellerozenblit in https://github.com/facebook/zstd/pull/3557 * Bump github/codeql-action from 2.2.6 to 2.2.8 by @dependabot in https://github.com/facebook/zstd/pull/3573 * Disable linker flag detection on MSVC/ClangCL. by @tru in https://github.com/facebook/zstd/pull/3569 * Couple tweaks to improve decompression speed with clang PGO compilation by @zhuhan0 in https://github.com/facebook/zstd/pull/3576 * Increase tests timeout by @dvoropaev in https://github.com/facebook/zstd/pull/3540 * added a Clang-CL Windows test to CI by @Cyan4973 in https://github.com/facebook/zstd/pull/3579 * Seekable format read optimization by @Cyan4973 in https://github.com/facebook/zstd/pull/3581 * Check that `dest` is valid for decompression by @daniellerozenblit in https://github.com/facebook/zstd/pull/3555 * fix decompression with -o writing into a block device by @Cyan4973 in https://github.com/facebook/zstd/pull/3584 * updated version number to v1.5.5 by @Cyan4973 in https://github.com/facebook/zstd/pull/3577 ## New Contributors * @kou made their first contribution in https://github.com/facebook/zstd/pull/3510 * @dloidolt made their first contribution in https://github.com/facebook/zstd/pull/3516 * @ppentchev made their first contribution in https://github.com/facebook/zstd/pull/3559 * @rickmark made their first contribution in https://github.com/facebook/zstd/pull/3568 * @dvoropaev made their first contribution in https://github.com/facebook/zstd/pull/3540 **Full Changelog**: https://github.com/facebook/zstd/compare/v1.5.4...v1.5.5 Zstandard `v1.5.4` is a pretty big release benefiting from one year of work, spread over > 650 commits. It offers significant performance improvements across multiple scenarios, as well as new features (detailed below). There is a crop of little bug fixes too, a few ones targeting the 32-bit mode are important enough to make this release a recommended upgrade. ### Various Speed improvements This release has accumulated a number of scenario-specific improvements, that cumulatively benefit a good portion of installed base in one way or another. Among the easier ones to describe, the repository has received several contributions for `arm` optimizations, notably from @JunHe77 and @danlark1. And @terrelln has improved decompression speed for non-x64 systems, including `arm`. The combination of this work is visible in the following example, using an M1-Pro (`aarch64` architecture) : | cpu | function | corpus | `v1.5.2` | `v1.5.4` | Improvement | | --- | --- | --- | --- | --- | --- | | M1 Pro | decompress | `silesia.tar` | 1370 MB/s | 1480 MB/s | + 8% | | Galaxy S22 | decompress | `silesia.tar` | 1150 MB/s | 1200 MB/s | + 4% | Middle compression levels (5-12) receive some care too, with @terrelln improving the dispatch engine, and @danlark1 offering `NEON` optimizations. Exact speed up vary depending on platform, cpu, compiler, and compression level, though one can expect gains ranging from +1 to +10% depending on scenarios. | cpu | function | corpus | `v1.5.2` | `v1.5.4` | Improvement | | --- | --- | --- | ---:| ---:| --- | | i7-9700k | compress -6 | `silesia.tar` | 110 MB/s | 121 MB/s | +10% | Galaxy S22 | compress -6 | `silesia.tar` | 98 MB/s | 103 MB/s | +5% | M1 Pro | compress -6 | `silesia.tar` | 122 MB/s | 130 MB/s | +6.5% | i7-9700k | compress -9 | `silesia.tar` | 64 MB/s | 70 MB/s | +9.5% | Galaxy S22 | compress -9 | `silesia.tar` | 51 MB/s | 52 MB/s | +1% | M1 Pro | compress -9 | `silesia.tar` | 77 MB/s | 86 MB/s | +11.5% | i7-9700k | compress -12 | `silesia.tar` | 31.6 MB/s | 31.8 MB/s | +0.5% | Galaxy S22 | compress -12 | `silesia.tar` | 20.9 MB/s | 22.1 MB/s | +5% | M1 Pro | compress -12 | `silesia.tar` | 36.1 MB/s | 39.7 MB/s | +10% Speed of the streaming compression interface has been improved by @embg in scenarios involving large files (where size is a multiple of the `windowSize` parameter). The improvement is mostly perceptible at high speeds (i.e. ~level 1). In the following sample, the measurement is taken directly at `ZSTD_compressStream()` function call, using a dedicated benchmark tool `tests/fullbench`. | cpu | function | corpus | `v1.5.2` | `v1.5.4` | Improvement | | --- | --- | --- | --- | --- | --- | | i7-9700k | `ZSTD_compressStream()` -1 | `silesia.tar` | 392 MB/s | 429 MB/s | +9.5% | | Galaxy S22 | `ZSTD_compressStream()` -1 | `silesia.tar` | 380 MB/s | 430 MB/s | +13% | | M1 Pro | `ZSTD_compressStream()` -1 | `silesia.tar` | 476 MB/s | 539 MB/s | +13% | Finally, dictionary compression speed has received a good boost by @embg. Exact outcome varies depending on system and corpus. The following result is achieved by cutting the `enwik8` compression corpus into 1KB blocks, generating a dictionary from these blocks, and then benchmarking the compression speed at level 1. | cpu | function | corpus | `v1.5.2` | `v1.5.4` | Improvement | | --- | --- | --- | --- | --- | --- | | i7-9700k | dictionary compress | `enwik8` -B1K | 125 MB/s | 165 MB/s | +32% | | Galaxy S22 | dictionary compress | `enwik8` -B1K | 138 MB/s | 166 MB/s | +20% | | M1 Pro | dictionary compress | `enwik8` -B1K | 155 MB/s | 195 MB/s | +25 % | There are a few more scenario-specifics improvements listed in the `changelog` section below. ### I/O Performance improvements The 1.5.4 release improves IO performance of `zstd` CLI, by using system buffers (`macos`) and adding a new asynchronous I/O capability, enabled by default on large files (when threading is available). The user can also explicitly control this capability with the `--[no-]asyncio` flag . These new threads remove the need to block on IO operations. The impact is mostly noticeable when decompressing large files (>= a few MBs), though exact outcome depends on environment and run conditions. Decompression speed gets significant gains due to its single-threaded serial nature and the high speeds involved. In some cases we observe up to double performance improvement (local Mac machines) and a wide +15-45% benefit on Intel Linux servers (see table for details). On the compression side of things, we’ve measured up to 5% improvements. The impact is lower because compression is already partially asynchronous via the internal MT mode (see release [v1.3.4](https://github.com/facebook/zstd/releases/tag/v1.3.4)). The following table shows the elapsed run time for decompressions of `silesia` and `enwik8` on several platforms - some Skylake-era Linux servers and an M1 MacbookPro. It compares the time it takes for version `v1.5.2` to version `v1.5.4` with asyncio on and off. platform | corpus | `v1.5.2` | `v1.5.4-no-asyncio` | `v1.5.4` | Improvement -- | -- | -- | -- | -- | -- Xeon D-2191A CentOS8 | `enwik8` | 280 MB/s | 280 MB/s | 324 MB/s | +16% Xeon D-2191A CentOS8 | `silesia.tar` | 303 MB/s | 302 MB/s | 386 MB/s | +27% i7-1165g7 win10 | `enwik8` | 270 MB/s | 280 MB/s | 350 MB/s | +27% i7-1165g7 win10 | `silesia.tar` | 450 MB/s | 440 MB/s | 580 MB/s | +28% i7-9700K Ubuntu20 | `enwik8` | 600 MB/s | 604 MB/s | 829 MB/s | +38% i7-9700K Ubuntu20 | `silesia.tar` | 683 MB/s | 678 MB/s | 991 MB/s | +45% Galaxy S22 | `enwik8` | 360 MB/s | 420 MB/s | 515 MB/s | +70% Galaxy S22 | `silesia.tar` | 310 MB/s | 320 MB/s | 580 MB/s | +85% MBP M1 | `enwik8` | 428 MB/s | 734 MB/s | 815 MB/s | +90% MBP M1 | `silesia.tar` | 465 MB/s | 875 MB/s | 1001 MB/s | +115% ### Support of externally-defined sequence producers `libzstd` can now support external sequence producers via a new advanced registration function `ZSTD_registerSequenceProducer()` (#3333). This API allows users to provide their own custom sequence producer which libzstd invokes to process each block. The produced list of sequences (literals and matches) is then post-processed by libzstd to produce valid compressed blocks. This block-level offload API is a more granular complement of the existing frame-level offload API `compressSequences()` (introduced in `v1.5.1`). It offers an easier migration story for applications already integrated with `libzstd`: the user application continues to invoke the same compression functions `ZSTD_compress2()` or `ZSTD_compressStream2()` as usual, and transparently benefits from the specific properties of the external sequence producer. For example, the sequence producer could be tuned to take advantage of known characteristics of the input, to offer better speed / ratio. One scenario that becomes possible is to combine this capability with hardware-accelerated matchfinders, such as the Intel® QuickAssist accelerator (Intel® QAT) provided in server CPUs such as the 4th Gen Intel® Xeon® Scalable processors (previously codenamed Sapphire Rapids). More details to be provided in future communications. ## Change Log perf: +20% faster huffman decompression for targets that can't compile x64 assembly (#3449, @terrelln) perf: up to +10% faster streaming compression at levels 1-2 (#3114, @embg) perf: +4-13% for levels 5-12 by optimizing function generation (#3295, @terrelln) pref: +3-11% compression speed for `arm` target (#3199, #3164, #3145, #3141, #3138, @JunHe77 and #3139, #3160, @danlark1) perf: +5-30% faster dictionary compression at levels 1-4 (#3086, #3114, #3152, @embg) perf: +10-20% cold dict compression speed by prefetching CDict tables (#3177, @embg) perf: +1% faster compression by removing a branch in ZSTD_fast_noDict (#3129, @felixhandte) perf: Small compression ratio improvements in high compression mode (#2983, #3391, @Cyan4973 and #3285, #3302, @daniellerozenblit) perf: small speed improvement by better detecting `STATIC_BMI2` for `clang` (#3080, @TocarIP) perf: Improved streaming performance when `ZSTD_c_stableInBuffer` is set (#2974, @Cyan4973) cli: Asynchronous I/O for improved cli speed (#2975, #2985, #3021, #3022, @yoniko) cli: Change `zstdless` behavior to align with `zless` (#2909, @binhdvo) cli: Keep original file if `-c` or `--stdout` is given (#3052, @dirkmueller) cli: Keep original files when result is concatenated into a single output with `-o` (#3450, @Cyan4973) cli: Preserve Permissions and Ownership of regular files (#3432, @felixhandte) cli: Print zlib/lz4/lzma library versions with `-vv` (#3030, @terrelln) cli: Print checksum value for single frame files with `-lv` (#3332, @Cyan4973) cli: Print `dictID` when present with `-lv` (#3184, @htnhan) cli: when `stderr` is *not* the console, disable status updates, but preserve final summary (#3458, @Cyan4973) cli: support `--best` and `--no-name` in `gzip` compatibility mode (#3059, @dirkmueller) cli: support for `posix` high resolution timer `clock_gettime()`, for improved benchmark accuracy (#3423, @Cyan4973) cli: improved help/usage (`-h`, `-H`) formatting (#3094, @dirkmueller and #3385, @jonpalmisc) cli: Fix better handling of bogus numeric values (#3268, @ctkhanhly) cli: Fix input consists of multiple files _and_ `stdin` (#3222, @yoniko) cli: Fix tiny files passthrough (#3215, @cgbur) cli: Fix for `-r` on empty directory (#3027, @brailovich) cli: Fix empty string as argument for `--output-dir-*` (#3220, @embg) cli: Fix decompression memory usage reported by `-vv --long` (#3042, @u1f35c, and #3232, @zengyijing) cli: Fix infinite loop when empty input is passed to trainer (#3081, @terrelln) cli: Fix `--adapt` doesn't work when `--no-progress` is also set (#3354, @terrelln) api: Support for External Sequence Producer (#3333, @embg) api: Support for in-place decompression (#3432, @terrelln) api: New `ZSTD_CCtx_setCParams()` function, set all parameters defined in a `ZSTD_compressionParameters` structure (#3403, @Cyan4973) api: Streaming decompression detects incorrect header ID sooner (#3175, @Cyan4973) api: Window size resizing optimization for edge case (#3345, @daniellerozenblit) api: More accurate error codes for busy-loop scenarios (#3413, #3455, @Cyan4973) api: Fix limit overflow in `compressBound` and `decompressBound` (#3362, #3373, Cyan4973) reported by @nigeltao api: Deprecate several advanced experimental functions: streaming (#3408, @embg), copy (#3196, @mileshu) bug: Fix corruption that rarely occurs in 32-bit mode with wlog=25 (#3361, @terrelln) bug: Fix for block-splitter (#3033, @Cyan4973) bug: Fixes for Sequence Compression API (#3023, #3040, @Cyan4973) bug: Fix leaking thread handles on Windows (#3147, @animalize) bug: Fix timing issues with cmake/meson builds (#3166, #3167, #3170, @Cyan4973) build: Allow user to select legacy level for cmake (#3050, @shadchin) build: Enable legacy support by default in cmake (#3079, @niamster) build: Meson build script improvements (#3039, #3120, #3122, #3327, #3357, @eli-schwartz and #3276, @neheb) build: Add aarch64 to supported architectures for zstd_trace (#3054, @ooosssososos) build: support AIX architecture (#3219, @qiongsiwu) build: Fix `ZSTD_LIB_MINIFY` build macro, which now reduces static library size by half (#3366, @terrelln) build: Fix Windows issues with Multithreading translation layer (#3364, #3380, @yoniko) and ARM64 target (#3320, @cwoffenden) build: Fix `cmake` script (#3382, #3392, @terrelln and #3252 @Tachi107 and #3167 @Cyan4973) doc: Updated man page, providing more details for `--train` mode (#3112, @Cyan4973) doc: Add decompressor errata document (#3092, @terrelln) misc: Enable Intel CET (#2992, #2994, @hjl-tools) misc: Fix `contrib/` seekable format (#3058, @yhoogstrate and #3346, @daniellerozenblit) misc: Improve speed of the one-file library generator (#3241, @wahern and #3005, @cwoffenden) ## PR list (generated by Github) * x86-64: Enable Intel CET by @hjl-tools in https://github.com/facebook/zstd/pull/2992 * Add GitHub Action Checking that Zstd Runs Successfully Under CET by @felixhandte in https://github.com/facebook/zstd/pull/3015 * [opt] minor compression ratio improvement by @Cyan4973 in https://github.com/facebook/zstd/pull/2983 * Simplify HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop by @WojciechMula in https://github.com/facebook/zstd/pull/3013 * Async write for decompression by @yoniko in https://github.com/facebook/zstd/pull/2975 * ZSTD CLI: Use buffered output by @yoniko in https://github.com/facebook/zstd/pull/2985 * Use faster Python script to amalgamate by @cwoffenden in https://github.com/facebook/zstd/pull/3005 * Change zstdless behavior to align with zless by @binhdvo in https://github.com/facebook/zstd/pull/2909 * AsyncIO compression part 1 - refactor of existing asyncio code by @yoniko in https://github.com/facebook/zstd/pull/3021 * Converge sumtype (offset | repcode) numeric representation towards offBase by @Cyan4973 in https://github.com/facebook/zstd/pull/2965 * fix sequence compression API in Explicit Delimiter mode by @Cyan4973 in https://github.com/facebook/zstd/pull/3023 * Lazy parameters adaptation (part 1 - ZSTD_c_stableInBuffer) by @Cyan4973 in https://github.com/facebook/zstd/pull/2974 * Print zlib/lz4/lzma library versions in verbose version output by @terrelln in https://github.com/facebook/zstd/pull/3030 * fix for -r on empty directory by @brailovich in https://github.com/facebook/zstd/pull/3027 * Add new CLI testing platform by @terrelln in https://github.com/facebook/zstd/pull/3020 * AsyncIO compression part 2 - added async read and asyncio to compression code by @yoniko in https://github.com/facebook/zstd/pull/3022 * Macos playtest envvars fix by @yoniko in https://github.com/facebook/zstd/pull/3035 * Fix required decompression memory usage reported by -vv + --long by @u1f35c in https://github.com/facebook/zstd/pull/3042 * Select legacy level for cmake by @shadchin in https://github.com/facebook/zstd/pull/3050 * [trace] Add aarch64 to supported architectures for zstd_trace by @ooosssososos in https://github.com/facebook/zstd/pull/3054 * New features for largeNbDicts benchmark by @embg in https://github.com/facebook/zstd/pull/3063 * Use helper function for bit manipulations. by @TocarIP in https://github.com/facebook/zstd/pull/3075 * [programs] Fix infinite loop when empty input is passed to trainer by @terrelln in https://github.com/facebook/zstd/pull/3081 * Enable STATIC_BMI2 for gcc/clang by @TocarIP in https://github.com/facebook/zstd/pull/3080 * build:cmake: enable ZSTD legacy support by default by @niamster in https://github.com/facebook/zstd/pull/3079 * Implement more gzip compatibility (#3037) by @dirkmueller in https://github.com/facebook/zstd/pull/3059 * [doc] Add decompressor errata document by @terrelln in https://github.com/facebook/zstd/pull/3092 * Handle newer less versions in zstdless testing by @dirkmueller in https://github.com/facebook/zstd/pull/3093 * [contrib][linux] Fix a warning in zstd_reset_cstream() by @cyberknight777 in https://github.com/facebook/zstd/pull/3088 * Software pipeline for ZSTD_compressBlock_fast_dictMatchState (+5-6% compression speed) by @embg in https://github.com/facebook/zstd/pull/3086 * Keep original file if -c or --stdout is given by @dirkmueller in https://github.com/facebook/zstd/pull/3052 * Split help in long and short version, cleanup formatting by @dirkmueller in https://github.com/facebook/zstd/pull/3094 * updated man page, providing more details for --train mode by @Cyan4973 in https://github.com/facebook/zstd/pull/3112 * Meson fixups for Windows by @eli-schwartz in https://github.com/facebook/zstd/pull/3039 * meson: for internal linkage, link to both libzstd and a static copy of it by @eli-schwartz in https://github.com/facebook/zstd/pull/3122 * Software pipeline for ZSTD_compressBlock_fast_extDict (+4-9% compression speed) by @embg in https://github.com/facebook/zstd/pull/3114 * ZSTD_fast_noDict: Avoid Safety Check When Writing `ip1` into Table by @felixhandte in https://github.com/facebook/zstd/pull/3129 * Correct and clarify repcode offset history logic by @embg in https://github.com/facebook/zstd/pull/3127 * [lazy] Optimize ZSTD_row_getMatchMask for levels 8-10 for ARM by @danlark1 in https://github.com/facebook/zstd/pull/3139 * fix leaking thread handles on Windows by @animalize in https://github.com/facebook/zstd/pull/3147 * Remove expensive assert in --rsyncable hot loop by @terrelln in https://github.com/facebook/zstd/pull/3154 * Bugfix for huge dictionaries by @embg in https://github.com/facebook/zstd/pull/3157 * common: apply two stage copy to aarch64 by @JunHe77 in https://github.com/facebook/zstd/pull/3145 * dec: adjust seqSymbol load on aarch64 by @JunHe77 in https://github.com/facebook/zstd/pull/3141 * Fix big endian ARM NEON path by @danlark1 in https://github.com/facebook/zstd/pull/3160 * [contrib] largeNbDicts bugfix + improvements by @embg in https://github.com/facebook/zstd/pull/3161 * display a warning message when using C90 clock_t by @Cyan4973 in https://github.com/facebook/zstd/pull/3166 * remove explicit standard setting from cmake script by @Cyan4973 in https://github.com/facebook/zstd/pull/3167 * removed gnu99 statement from meson recipe by @Cyan4973 in https://github.com/facebook/zstd/pull/3170 * "Short cache" optimization for level 1-4 DMS (+5-30% compression speed) by @embg in https://github.com/facebook/zstd/pull/3152 * Streaming decompression can detect incorrect header ID sooner by @Cyan4973 in https://github.com/facebook/zstd/pull/3175 * Add prefetchCDictTables CCtxParam (+10-20% cold dict compression speed) by @embg in https://github.com/facebook/zstd/pull/3177 * Fix ZSTD_BUILD_TESTS=ON with MSVC by @nocnokneo in https://github.com/facebook/zstd/pull/3180 * zstd -lv <file> to show dictID by @htnhan in https://github.com/facebook/zstd/pull/3184 * Intial commit to address 3090. Added support to decompress empty block. by @udayanbapat in https://github.com/facebook/zstd/pull/3118 * [largeNbDicts] Second try at fixing decompression segfault to always create compressInstructions by @zhuhan0 in https://github.com/facebook/zstd/pull/3209 * Clarify benchmark chunking docstring by @embg in https://github.com/facebook/zstd/pull/3197 * decomp: add prefetch for matched seq on aarch64 by @JunHe77 in https://github.com/facebook/zstd/pull/3164 * lib: add hint to generate more pipeline friendly code by @JunHe77 in https://github.com/facebook/zstd/pull/3138 * [AIX] Fix Compiler Flags and Bugs on AIX to Pass All Tests by @qiongsiwu in https://github.com/facebook/zstd/pull/3219 * zlibWrapper: Update for zlib 1.2.12 by @orbea in https://github.com/facebook/zstd/pull/3217 * Fix small file passthrough by @cgbur in https://github.com/facebook/zstd/pull/3215 * Add warning when multi-thread decompression is requested by @tomcwang in https://github.com/facebook/zstd/pull/3208 * stdin + multiple file fixes by @yoniko in https://github.com/facebook/zstd/pull/3222 * [AIX] Fixing hash4Ptr for Big Endian Systems by @qiongsiwu in https://github.com/facebook/zstd/pull/3227 * Disallow empty string as argument for --output-dir-flat and --output-dir-mirror by @embg in https://github.com/facebook/zstd/pull/3220 * Deprecate ZSTD_getDecompressedSize() by @terrelln in https://github.com/facebook/zstd/pull/3225 * [T124890272] Mark 2 Obsolete Functions(ZSTD_copy*Ctx) Deprecated in Zstd by @mileshu in https://github.com/facebook/zstd/pull/3196 * fileio_types.h : avoid dependency on mem.h by @Cyan4973 in https://github.com/facebook/zstd/pull/3232 * fixed: verbose output prints wrong value for `wlog` when doing `--long` by @zengyijing in https://github.com/facebook/zstd/pull/3226 * Add explicit --pass-through flag and default to enabled for *cat by @terrelln in https://github.com/facebook/zstd/pull/3223 * Document pass-through behavior by @cgbur in https://github.com/facebook/zstd/pull/3242 * restore combine.sh bash performance while still sticking to POSIX by @wahern in https://github.com/facebook/zstd/pull/3241 * Benchmark program for sequence compression API by @embg in https://github.com/facebook/zstd/pull/3257 * streamline `make clean` list maintenance by adding a `CLEAN` variable by @Cyan4973 in https://github.com/facebook/zstd/pull/3256 * drop `-E` flag in `sed` by @haampie in https://github.com/facebook/zstd/pull/3245 * compress:check more bytes to reduce `ZSTD_count` call by @JunHe77 in https://github.com/facebook/zstd/pull/3199 * build(cmake): improve pkg-config generation by @Tachi107 in https://github.com/facebook/zstd/pull/3252 * Fix for `zstd` CLI accepts bogus values for numeric parameters by @ctkhanhly in https://github.com/facebook/zstd/pull/3268 * ci: test pkg-config file by @Tachi107 in https://github.com/facebook/zstd/pull/3267 * Move ZSTD_DEPRECATED before ZSTDLIB_API/ZSTDLIB_STATIC_API for `clang` by @MaskRay in https://github.com/facebook/zstd/pull/3273 * Enable OpenSSF Scorecard Action by @felixhandte in https://github.com/facebook/zstd/pull/3277 * fixed zstd-pgo target for GCC by @ilyakurdyukov in https://github.com/facebook/zstd/pull/3281 * Cleaner threadPool initialization by @Cyan4973 in https://github.com/facebook/zstd/pull/3288 * Make fuzzing work without ZSTD_MULTITHREAD by @danlark1 in https://github.com/facebook/zstd/pull/3291 * Optimal huf depth by @daniellerozenblit in https://github.com/facebook/zstd/pull/3285 * Make ZSTD_getDictID_fromDDict() Read DictID from DDict by @felixhandte in https://github.com/facebook/zstd/pull/3290 * [contrib][linux-kernel] Generate SPDX license identifiers by @ojeda in https://github.com/facebook/zstd/pull/3294 * [lazy] Use switch instead of indirect function calls, improving compression speed by @terrelln in https://github.com/facebook/zstd/pull/3295 * [linux] Add zstd_common module by @terrelln in https://github.com/facebook/zstd/pull/3292 * Complete migration of ZSTD_c_enableLongDistanceMatching to ZSTD_paramSwitch_e framework by @embg in https://github.com/facebook/zstd/pull/3321 * meson: get version up front by @eli-schwartz in https://github.com/facebook/zstd/pull/3327 * Fix for MSVC C4267 warning on ARM64 (which becomes error C2220 with /WX) by @cwoffenden in https://github.com/facebook/zstd/pull/3320 * Enable dependabot for automatic GitHub Actions updates by @DimitriPapadopoulos in https://github.com/facebook/zstd/pull/3284 * Print checksum value for single frame files in cli with -v -l options by @Cyan4973 in https://github.com/facebook/zstd/pull/3332 * Fix window size resizing optimization for edge case by @daniellerozenblit in https://github.com/facebook/zstd/pull/3345 * [linux-kernel] Fix stack detection for newer gcc by @terrelln in https://github.com/facebook/zstd/pull/3348 * Reserve two fields in ZSTD_frameHeader by @embg in https://github.com/facebook/zstd/pull/3349 * Fix seekable format for empty string by @daniellerozenblit in https://github.com/facebook/zstd/pull/3346 * meson: make backtrace dependency on execinfo for musl libc compatibility by @neheb in https://github.com/facebook/zstd/pull/3276 * Refactor progress bar & summary line logic by @terrelln in https://github.com/facebook/zstd/pull/2984 * Use `__attribute__((aligned(1)))` for unaligned access by @Hello71 in https://github.com/facebook/zstd/pull/2881 * Separate parameter adaption from display update rate by @terrelln in https://github.com/facebook/zstd/pull/3354 * [decompress] Fix UB nullptr addition & improve fuzzer by @terrelln in https://github.com/facebook/zstd/pull/3356 * [legacy] Simplify legacy codebase by removing esoteric memory accesses and only use memcpy by @terrelln in https://github.com/facebook/zstd/pull/3355 * Fix corruption that rarely occurs in 32-bit mode with wlog=25 by @terrelln in https://github.com/facebook/zstd/pull/3361 * meson: partial fix for building pzstd on MSVC by @eli-schwartz in https://github.com/facebook/zstd/pull/3357 * [CI] Re-enable versions-test by @terrelln in https://github.com/facebook/zstd/pull/3371 * [api][visibility] Make the visibility macros more consistent by @terrelln in https://github.com/facebook/zstd/pull/3363 * [build] Fix ZSTD_LIB_MINIFY build option by @terrelln in https://github.com/facebook/zstd/pull/3366 * [zdict] Fix static linking only include guards by @terrelln in https://github.com/facebook/zstd/pull/3372 * check potential overflow of compressBound() by @Cyan4973 in https://github.com/facebook/zstd/pull/3362 * decompressBound tests and fix by @Cyan4973 in https://github.com/facebook/zstd/pull/3373 * Meson test fixups by @eli-schwartz in https://github.com/facebook/zstd/pull/3120 * [pzstd] Fixes for Windows build by @terrelln in https://github.com/facebook/zstd/pull/3380 * Windows MT layer bug fixes by @yoniko in https://github.com/facebook/zstd/pull/3364 * Update Copyright Comments by @felixhandte in https://github.com/facebook/zstd/pull/3173 * [docs] Clarify dictionary loading documentation by @terrelln in https://github.com/facebook/zstd/pull/3381 * [build][cmake] Fix cmake with custom assembler by @terrelln in https://github.com/facebook/zstd/pull/3382 * Pin actions/checkout Dependency to Specific Commit Hash by @felixhandte in https://github.com/facebook/zstd/pull/3384 * Improve help/usage (`-h`, `-H`) formatting by @jonpalmisc in https://github.com/facebook/zstd/pull/3385 * [cmake] Add noexecstack to compiler/linker flags by @terrelln in https://github.com/facebook/zstd/pull/3392 * Fix `-Wdocumentation` by @terrelln in https://github.com/facebook/zstd/pull/3393 * Support decompression of compressed blocks of size ZSTD_BLOCKSIZE_MAX by @Cyan4973 in https://github.com/facebook/zstd/pull/3399 * spec update : require minimum nb of literals for 4-streams mode by @Cyan4973 in https://github.com/facebook/zstd/pull/3398 * External matchfinder API by @embg in https://github.com/facebook/zstd/pull/3333 * New `ZSTD_CCtx_setCParams()` entry point, to set all parameters defined in a `ZSTD_compressionParameters` structure by @Cyan4973 in https://github.com/facebook/zstd/pull/3403 * Move deprecated annotation before static to allow C++ compilation for clang by @danlark1 in https://github.com/facebook/zstd/pull/3400 * Optimal huff depth speed improvements by @daniellerozenblit in https://github.com/facebook/zstd/pull/3302 * improve compression ratio of small alphabets by @Cyan4973 in https://github.com/facebook/zstd/pull/3391 * Fix fuzzing with ZSTD_MULTITHREAD by @danlark1 in https://github.com/facebook/zstd/pull/3417 * minor refactoring for timefn by @Cyan4973 in https://github.com/facebook/zstd/pull/3413 * Add support for in-place decompression by @terrelln in https://github.com/facebook/zstd/pull/3421 * fix when nb of literals is very small by @Cyan4973 in https://github.com/facebook/zstd/pull/3419 * Deprecate advanced streaming functions by @embg in https://github.com/facebook/zstd/pull/3408 * Disable Custom ASAN/MSAN Poisoning on MinGW Builds by @felixhandte in https://github.com/facebook/zstd/pull/3424 * [tests] Fix version test determinism by @terrelln in https://github.com/facebook/zstd/pull/3422 * Refactor `timefn` unit, restore support for `clock_gettime()` by @Cyan4973 in https://github.com/facebook/zstd/pull/3423 * Fuzz on maxBlockSize by @daniellerozenblit in https://github.com/facebook/zstd/pull/3418 * Fuzz the External Matchfinder API by @embg in https://github.com/facebook/zstd/pull/3437 * Cap hashLog & chainLog to ensure that we only use 32 bits of hash by @terrelln in https://github.com/facebook/zstd/pull/3438 * [versions-test] Work around bug in dictionary builder for older versions by @terrelln in https://github.com/facebook/zstd/pull/3436 * added c89 build test to CI by @Cyan4973 in https://github.com/facebook/zstd/pull/3435 * added cygwin tests to Github Actions by @Cyan4973 in https://github.com/facebook/zstd/pull/3431 * Huffman refactor by @terrelln in https://github.com/facebook/zstd/pull/3434 * Fix bufferless API with attached dictionary by @terrelln in https://github.com/facebook/zstd/pull/3441 * Test PGO Builds by @felixhandte in https://github.com/facebook/zstd/pull/3442 * Fix CLI Handling of Permissions and Ownership by @felixhandte in https://github.com/facebook/zstd/pull/3432 * Fix -Wstringop-overflow warning by @terrelln in https://github.com/facebook/zstd/pull/3440 * refactor : --rm ignored with stdout by @Cyan4973 in https://github.com/facebook/zstd/pull/3443 * Fix sequence validation and seqStore bounds check by @daniellerozenblit in https://github.com/facebook/zstd/pull/3439 * Fix ZSTD_estimate* and ZSTD_initCStream() docs by @embg in https://github.com/facebook/zstd/pull/3448 * Fix 32-bit build errors in zstd seekable format by @daniellerozenblit in https://github.com/facebook/zstd/pull/3452 * Fuzz large offsets through sequence compression api by @daniellerozenblit in https://github.com/facebook/zstd/pull/3447 * [huf] Add generic C versions of the fast decoding loops by @terrelln in https://github.com/facebook/zstd/pull/3449 * Provide more accurate error codes for busy-loop scenarios by @Cyan4973 in https://github.com/facebook/zstd/pull/3455 * disable --rm on -o command by @Cyan4973 in https://github.com/facebook/zstd/pull/3450 * [Bugfix] CLI row hash flags set the wrong values by @yoniko in https://github.com/facebook/zstd/pull/3457 * [huf] Fix bug in fast C decoders by @terrelln in https://github.com/facebook/zstd/pull/3459 * Disable status updates when `stderr` is not the console by @Cyan4973 in https://github.com/facebook/zstd/pull/3458 * fix long offset resolution by @daniellerozenblit in https://github.com/facebook/zstd/pull/3460 * Simplify 32-bit long offsets decoding logic by @terrelln in https://github.com/facebook/zstd/pull/3467 ## New Contributors * @WojciechMula made their first contribution in https://github.com/facebook/zstd/pull/3013 * @trixirt made their first contribution in https://github.com/facebook/zstd/pull/3026 * @brailovich made their first contribution in https://github.com/facebook/zstd/pull/3027 * @u1f35c made their first contribution in https://github.com/facebook/zstd/pull/3042 * @shadchin made their first contribution in https://github.com/facebook/zstd/pull/3050 * @ooosssososos made their first contribution in https://github.com/facebook/zstd/pull/3054 * @TocarIP made their first contribution in https://github.com/facebook/zstd/pull/3075 * @xry111 made their first contribution in https://github.com/facebook/zstd/pull/3084 * @niamster made their first contribution in https://github.com/facebook/zstd/pull/3079 * @dirkmueller made their first contribution in https://github.com/facebook/zstd/pull/3059 * @cyberknight777 made their first contribution in https://github.com/facebook/zstd/pull/3088 * @dpelle made their first contribution in https://github.com/facebook/zstd/pull/3095 * @paulmenzel made their first contribution in https://github.com/facebook/zstd/pull/3108 * @cuishuang made their first contribution in https://github.com/facebook/zstd/pull/3117 * @averred made their first contribution in https://github.com/facebook/zstd/pull/3135 * @JunHe77 made their first contribution in https://github.com/facebook/zstd/pull/3145 * @htnhan made their first contribution in https://github.com/facebook/zstd/pull/3184 * @udayanbapat made their first contribution in https://github.com/facebook/zstd/pull/3118 * @zhuhan0 made their first contribution in https://github.com/facebook/zstd/pull/3205 * @mgord9518 made their first contribution in https://github.com/facebook/zstd/pull/3218 * @qiongsiwu made their first contribution in https://github.com/facebook/zstd/pull/3219 * @orbea made their first contribution in https://github.com/facebook/zstd/pull/3217 * @cgbur made their first contribution in https://github.com/facebook/zstd/pull/3215 * @tomcwang made their first contribution in https://github.com/facebook/zstd/pull/3208 * @mileshu made their first contribution in https://github.com/facebook/zstd/pull/3196 * @zengyijing made their first contribution in https://github.com/facebook/zstd/pull/3226 * @grossws made their first contribution in https://github.com/facebook/zstd/pull/3230 * @wahern made their first contribution in https://github.com/facebook/zstd/pull/3241 * @daniellerozenblit made their first contribution in https://github.com/facebook/zstd/pull/3258 * @DimitriPapadopoulos made their first contribution in https://github.com/facebook/zstd/pull/3259 * @sashashura made their first contribution in https://github.com/facebook/zstd/pull/3264 * @haampie made their first contribution in https://github.com/facebook/zstd/pull/3247 * @Tachi107 made their first contribution in https://github.com/facebook/zstd/pull/3252 * @ctkhanhly made their first contribution in https://github.com/facebook/zstd/pull/3268 * @MaskRay made their first contribution in https://github.com/facebook/zstd/pull/3273 * @ilyakurdyukov made their first contribution in https://github.com/facebook/zstd/pull/3281 * @ojeda made their first contribution in https://github.com/facebook/zstd/pull/3294 * @GermanAizek made their first contribution in https://github.com/facebook/zstd/pull/3304 * @joycebrum made their first contribution in https://github.com/facebook/zstd/pull/3309 * @yiyuaner made their first contribution in https://github.com/facebook/zstd/pull/3300 * @nmoinvaz made their first contribution in https://github.com/facebook/zstd/pull/3289 * @jonpalmisc made their first contribution in https://github.com/facebook/zstd/pull/3385 **Full Automated Changelog**: https://github.com/facebook/zstd/compare/v1.5.2...v1.5.4 Zstandard v1.5.2 is a bug-fix release, addressing issues that were raised with the v1.5.1 release. In particular, as a side-effect of the inclusion of assembly code in our source tree, binary artifacts were being marked as needing an executable stack on non-amd64 architectures. This release corrects that issue. More context is available in #2963. This release also corrects a performance regression that was introduced in v1.5.0 that slows down compression of very small data when using the streaming API. Issue #2966 tracks that topic. In addition there are a number of smaller improvements and fixes. ## Full Changelist * Fix zstd-static output name with MINGW/Clang by @MehdiChinoune in https://github.com/facebook/zstd/pull/2947 * storeSeq & mlBase : clarity refactoring by @Cyan4973 in https://github.com/facebook/zstd/pull/2954 * Fix mini typo by @fwessels in https://github.com/facebook/zstd/pull/2960 * Refactor offset+repcode sumtype by @Cyan4973 in https://github.com/facebook/zstd/pull/2962 * meson: fix MSVC support by @eli-schwartz in https://github.com/facebook/zstd/pull/2951 * fix performance issue in scenario #2966 (part 1) by @Cyan4973 in https://github.com/facebook/zstd/pull/2969 * [meson] Explicitly disable assembly for non clang/gcc copmilers by @terrelln in https://github.com/facebook/zstd/pull/2972 * Mark Huffman Decoder Assembly `noexecstack` on All Architectures by @felixhandte in https://github.com/facebook/zstd/pull/2964 * Improve Module Map File by @felixhandte in https://github.com/facebook/zstd/pull/2953 * Remove Dependencies to Allow the Zstd Binary to Dynamically Link to the Library by @felixhandte in https://github.com/facebook/zstd/pull/2977 * [opt] Fix oss-fuzz bug in optimal parser by @terrelln in https://github.com/facebook/zstd/pull/2980 * [license] Fix license header of huf_decompress_amd64.S by @terrelln in https://github.com/facebook/zstd/pull/2981 * Fix `stderr` progress logging for decompression by @terrelln in https://github.com/facebook/zstd/pull/2982 * Fix tar test cases by @sunwire in https://github.com/facebook/zstd/pull/2956 * Fixup MSVC source file inclusion for cmake builds by @hmaarrfk in https://github.com/facebook/zstd/pull/2957 * x86-64: Hide internal assembly functions by @hjl-tools in https://github.com/facebook/zstd/pull/2993 * Prepare v1.5.2 by @felixhandte in https://github.com/facebook/zstd/pull/2987 * Documentation and minor refactor to clarify MT memory management by @embg in https://github.com/facebook/zstd/pull/3000 * Avoid updating timestamps when the destination is `stdout` by @floppym in https://github.com/facebook/zstd/pull/2998 * [build][asm] Pass ASFLAGS to the assembler instead of CFLAGS by @terrelln in https://github.com/facebook/zstd/pull/3009 * Update CI documentation by @embg in https://github.com/facebook/zstd/pull/2999 ## New Contributors * @MehdiChinoune made their first contribution in https://github.com/facebook/zstd/pull/2947 * @fwessels made their first contribution in https://github.com/facebook/zstd/pull/2960 * @sunwire made their first contribution in https://github.com/facebook/zstd/pull/2956 * @hmaarrfk made their first contribution in https://github.com/facebook/zstd/pull/2957 * @floppym made their first contribution in https://github.com/facebook/zstd/pull/2998 **Full Changelog**: https://github.com/facebook/zstd/compare/v1.5.1...v1.5.2 __Notice__ : it has been brought to our attention that the `v1.5.1` library might be built with an executable stack on non-`x64` architectures, which could end up being flagged as problematic by some systems with thorough security settings which disallow executable stack. We are currently reviewing the issue. Be aware of it if you build `libzstd` for non-`x64` architecture. Zstandard v1.5.1 is a maintenance release, bringing a good number of small refinements to the project. It also offers a welcome crop of performance improvements, as detailed below. ## Performance Improvements ### Speed improvements for fast compression (levels 1–4) PRs #2749, #2774, and #2921 refactor single-segment compression for `ZSTD_fast` and `ZSTD_dfast`, which back compression levels 1 through 4 (as well as the negative compression levels). Speedups in the ~3-5% range are observed. In addition, the compression ratio of `ZSTD_dfast` (levels 3 and 4) is slightly improved. ### Rebalanced middle compression levels `v1.5.0` introduced major speed improvements for mid-level compression (from 5 to 12), while preserving roughly similar compression ratio. As a consequence, the speed scale became tilted towards faster speed. Unfortunately, the difference between successive levels was no longer regular, and there is a large performance gap just after the impacted range, between levels 12 and 13. `v1.5.1` tries to rebalance parameters so that compression levels can be roughly associated to their former speed budget. Consequently, `v1.5.1` mid compression levels feature speeds closer to former `v1.4.9` (though still sensibly faster) and receive in exchange an improved compression ratio, as shown in below graph.   Note that, since middle levels only experience a rebalancing, save some special cases, no significant performance differences between versions `v1.5.0` and `v1.5.1` should be expected: levels merely occupy different positions on the same curve. The situation is a bit different for fast levels (1-4), for which `v1.5.1` delivers a small but consistent performance benefit on all platforms, as described in previous paragraph. ### Huffman Improvements Our Huffman code was significantly revamped in this release. Both encoding and decoding speed were improved. Additionally, encoding speed for small inputs was improved even further. Speed is measured on the Silesia corpus by compressing with level 1 and extracting the literals left over after compression. Then compressing and decompressing the literals from each block. Measurements are done on an Intel i9-9900K @ 3.6 GHz. | Compiler | Scenario | v1.5.0 Speed | v1.5.1 Speed | Delta | |----------|-------------------------------------|--------------|--------------|--------| | gcc-11 | Literal compression - 128KB block | 748 MB/s | 927 MB/s | +23.9% | | clang-13 | Literal compression - 128KB block | 810 MB/s | 927 MB/s | +14.4% | | gcc-11 | Literal compression - 4KB block | 223 MB/s | 321 MB/s | +44.0% | | clang-13 | Literal compression - 4KB block | 224 MB/s | 310 MB/s | +38.2% | | gcc-11 | Literal decompression - 128KB block | 1164 MB/s | 1500 MB/s | +28.8% | | clang-13 | Literal decompression - 128KB block | 1006 MB/s | 1504 MB/s | +49.5% | Overall impact on (de)compression speed depends on the compressibility of the data. Compression speed improves from 1-4%, and decompression speed improves from 5-15%. PR #2722 implements the Huffman decoder in assembly for x86-64 with BMI2 enabled. We detect BMI2 support at runtime, so this speedup applies to all x86-64 builds running on CPUs that support BMI2. This improves Huffman decoding speed by about 40%, depending on the scenario. PR #2733 improves Huffman encoding speed by 10% for clang and 20% for gcc. PR #2732 drastically speeds up the `HUF_sort()` function, which speeds up Huffman tree building for compression. This is a significant speed boost for small inputs, measuring in at a 40% improvement for 4K inputs. ## Binary Size and Build Speed `zstd` binary size grew significantly in `v1.5.0` due to the new code added for middle compression level speed optimizations. In this release we recover the binary size, and in the process also significantly speed up builds, especially with sanitizers enabled. Measured on x86-64 compiled with `-O3` we measure `libzstd.a` size. We regained 161 KB of binary size on gcc, and 293 KB of binary size on clang. Note that these binary sizes are listed for the whole library, optimized for speed over size. The decoder only, with size saving options enabled, and compiled with `-Os` or `-Oz` can be much smaller. | Version | gcc-11 size | clang-13 size | |---------|-------------|---------------| | v1.5.1 | 1177 KB | 1167 KB | | v1.5.0 | 1338 KB | 1460 KB | | v1.4.9 | 1137 KB | 1151 KB | ## Change log ### Featured user-visible changes - perf: rebalanced compression levels, to better match intended speed/level curve, by @senhuang42 and @cyan4973 - perf: faster huffman decoder, using `x64` assembly, by @terrelln - perf: slightly faster high speed modes (strategies fast & dfast), by @felixhandte - perf: smaller binary size and faster compilation times, by @terrelln and @nolange - perf: new row64 mode, used notably at highest `lazy2` levels 11-12, by @senhuang42 - perf: faster mid-level compression speed in presence of highly repetitive patterns, by @senhuang42 - perf: minor compression ratio improvements for small data at high levels, by @cyan4973 - perf: reduced stack usage (mostly useful for Linux Kernel), by @terrelln - perf: faster compression speed on incompressible data, by @bindhvo - perf: on-demand reduced `ZSTD_DCtx` state size, using build macro `ZSTD_DECODER_INTERNAL_BUFFER`, at a small cost of performance, by @bindhvo - build: allows hiding static symbols in the dynamic library, using build macro, by @skitt - build: support for `m68k` (Motorola 68000's), by @cyan4973 - build: improved `AIX` support, by @Helflym - build: improved meson unofficial build, by @eli-schwartz - cli : fix : forward `mtime` to output file, by @felixhandte - cli : custom memory limit when training dictionary (#2925), by @embg - cli : report advanced parameters information when compressing in very verbose mode (`-vv`), by @Svetlitski-FB - cli : advanced commands in the form `--long-param=` can accept negative value arguments, by @binhdvo ### PR full list * Add determinism fuzzers and fix rare determinism bugs by @terrelln in https://github.com/facebook/zstd/pull/2648 * `ZSTD_VecMask_next`: fix incorrect variable name in fallback code path by @dnelson-1901 in https://github.com/facebook/zstd/pull/2657 * improve tar compatibility by @Cyan4973 in https://github.com/facebook/zstd/pull/2660 * Enable SSE2 compression path to work on MSVC by @TrianglesPCT in https://github.com/facebook/zstd/pull/2653 * Fix CircleCI Config to Fully Remove `publish-github-release` Job by @felixhandte in https://github.com/facebook/zstd/pull/2649 * [CI] Fix zlib-wrapper test by @senhuang42 in https://github.com/facebook/zstd/pull/2668 * [CI] Add ARM tests back into CI by @senhuang42 in https://github.com/facebook/zstd/pull/2667 * [trace] Refine the ZSTD_HAVE_WEAK_SYMBOLS detection by @terrelln in https://github.com/facebook/zstd/pull/2674 * [CI][1/2] Re-do the github actions workflows, migrate various travis and appveyor tests. by @senhuang42 in https://github.com/facebook/zstd/pull/2675 * Make GH Actions CI tests run apt-get update before apt-get install by @senhuang42 in https://github.com/facebook/zstd/pull/2682 * Add arm64 fuzz test to travis by @senhuang42 in https://github.com/facebook/zstd/pull/2686 * Add ldm and block splitter auto-enable to old api by @senhuang42 in https://github.com/facebook/zstd/pull/2684 * Add documentation for --patch-from by @binhdvo in https://github.com/facebook/zstd/pull/2693 * Make regression test run on every PR by @senhuang42 in https://github.com/facebook/zstd/pull/2691 * Initialize "potentially uninitialized" pointers. by @wolfpld in https://github.com/facebook/zstd/pull/2654 * Flatten `ZSTD_row_getMatchMask` by @aqrit in https://github.com/facebook/zstd/pull/2681 * Update `README` for Travis CI Badge by @gauthamkrishna9991 in https://github.com/facebook/zstd/pull/2700 * Fuzzer test with no intrinsics on `S390x` (big endian) by @senhuang42 in https://github.com/facebook/zstd/pull/2678 * Fix `--progress` flag to properly control progress display and default … by @binhdvo in https://github.com/facebook/zstd/pull/2698 * [bug] Fix entropy repeat mode bug by @senhuang42 in https://github.com/facebook/zstd/pull/2697 * Format File Sizes Human-Readable in the cli by @felixhandte in https://github.com/facebook/zstd/pull/2702 * Add support for negative values in advanced flags by @binhdvo in https://github.com/facebook/zstd/pull/2705 * [fix] Add missing bounds checks during compression by @terrelln in https://github.com/facebook/zstd/pull/2709 * Add API for fetching skippable frame content by @binhdvo in https://github.com/facebook/zstd/pull/2708 * Add option to use logical cores for default threads by @binhdvo in https://github.com/facebook/zstd/pull/2710 * lib/Makefile: Fix small typo in `ZSTD_FORCE_DECOMPRESS_*` build macros by @luisdallos in https://github.com/facebook/zstd/pull/2714 * [RFC] Add internal API for converting `ZSTD_Sequence` into `seqStore` by @senhuang42 in https://github.com/facebook/zstd/pull/2715 * Optimize zstd decompression by another x% by @danlark1 in https://github.com/facebook/zstd/pull/2689 * Include what you use in `zstd_ldm_geartab` by @danlark1 in https://github.com/facebook/zstd/pull/2719 * [trace] remove zstd_trace.c reference from freestanding by @heitbaum in https://github.com/facebook/zstd/pull/2655 * Remove folder when done with test by @senhuang42 in https://github.com/facebook/zstd/pull/2720 * Proactively skip huffman compression based on sampling where non-comp… by @binhdvo in https://github.com/facebook/zstd/pull/2717 * Add support for MCST LCC compiler by @makise-homura in https://github.com/facebook/zstd/pull/2725 * [bug-fix] Fix a determinism bug with the DUBT by @terrelln in https://github.com/facebook/zstd/pull/2726 * Fix DDSS Load by @felixhandte in https://github.com/facebook/zstd/pull/2729 * `Z_PREFIX zError` function by @koalabearguo in https://github.com/facebook/zstd/pull/2707 * `pzstd`: fix linking for static builds by @jonringer in https://github.com/facebook/zstd/pull/2724 * [HUF] Improve Huffman encoding speed by @terrelln in https://github.com/facebook/zstd/pull/2733 * [HUF] Improve Huffman sorting algorithm by @senhuang42 in https://github.com/facebook/zstd/pull/2732 * Set `mtime` on Output Files by @felixhandte in https://github.com/facebook/zstd/pull/2742 * [RFC] Rebalance compression levels by @senhuang42 in https://github.com/facebook/zstd/pull/2692 * Improve branch misses on FSE symbol spreading by @senhuang42 in https://github.com/facebook/zstd/pull/2750 * make `ZSTD_HASHLOG3_MAX` private by @Cyan4973 in https://github.com/facebook/zstd/pull/2752 * meson fixups by @eli-schwartz in https://github.com/facebook/zstd/pull/2746 * [easy] Fix zstd bench error message by @senhuang42 in https://github.com/facebook/zstd/pull/2753 * Reduce test time on TravisCI by @Cyan4973 in https://github.com/facebook/zstd/pull/2757 * added `qemu` tests by @Cyan4973 in https://github.com/facebook/zstd/pull/2758 * Add 8 bytes to FSE_buildCTable wksp by @senhuang42 in https://github.com/facebook/zstd/pull/2761 * minor rebalancing of level 13 by @Cyan4973 in https://github.com/facebook/zstd/pull/2762 * Improve compile speed and binary size in `opt` by @senhuang42 in https://github.com/facebook/zstd/pull/2763 * [easy] Fix patch-from help msg typo by @senhuang42 in https://github.com/facebook/zstd/pull/2769 * Pipelined Implementation of `ZSTD_fast` (~+5% Speed) by @felixhandte in https://github.com/facebook/zstd/pull/2749 * meson: fix type error for integer option by @eli-schwartz in https://github.com/facebook/zstd/pull/2775 * Fix dictionary training huffman segfault and small speed improvement by @senhuang42 in https://github.com/facebook/zstd/pull/2773 * [rsyncable] Ensure `ZSTD_compressBound()` is respected by @terrelln in https://github.com/facebook/zstd/pull/2776 * Improve optimal parser performance on small data by @Cyan4973 in https://github.com/facebook/zstd/pull/2771 * [rsyncable] Fix test failures by @terrelln in https://github.com/facebook/zstd/pull/2777 * Revert opt outlining change by @senhuang42 in https://github.com/facebook/zstd/pull/2778 * [build] Add support for ASM files in `Make` + `CMake` by @terrelln in https://github.com/facebook/zstd/pull/2783 * add `msvc2019` to build.generic.cmd by @animalize in https://github.com/facebook/zstd/pull/2787 * [fuzzer] Add Huffman decompression fuzzer by @terrelln in https://github.com/facebook/zstd/pull/2784 * Assembly implementation of 4X1 & 4X2 Huffman by @terrelln in https://github.com/facebook/zstd/pull/2722 * [huf] Fix compilation when `DYNAMIC_BMI2=0 && BMI2` is supported by @terrelln in https://github.com/facebook/zstd/pull/2791 * Use new paramSwitch enum for row matchfinder and block splitter by @senhuang42 in https://github.com/facebook/zstd/pull/2788 * Fix `NCountWriteBound` by @senhuang42 in https://github.com/facebook/zstd/pull/2779 * [contrib][linux] Fix up SPDX license identifiers by @terrelln in https://github.com/facebook/zstd/pull/2794 * [contrib][linux] Reduce stack usage by 80 bytes by @terrelln in https://github.com/facebook/zstd/pull/2795 * Reduce stack usage of block splitter by @senhuang42 in https://github.com/facebook/zstd/pull/2780 * minor: constify `MatchState*` parameter when possible by @Cyan4973 in https://github.com/facebook/zstd/pull/2797 * [build] Fix oss-fuzz build with the dataflow sanitizer by @terrelln in https://github.com/facebook/zstd/pull/2799 * [lib] Make lib compatible with `-Wfall-through` excepting legacy by @terrelln in https://github.com/facebook/zstd/pull/2796 * [contrib][linux] Fix build after introducing ASM HUF implementation by @solbjorn in https://github.com/facebook/zstd/pull/2790 * Smaller code with disabled features by @nolange in https://github.com/facebook/zstd/pull/2805 * [huf] Fix OSS-Fuzz assert by @terrelln in https://github.com/facebook/zstd/pull/2808 * Skip most long matches in lazy hash table update by @senhuang42 in https://github.com/facebook/zstd/pull/2755 * add missing BUNDLE DESTINATION by @3nids in https://github.com/facebook/zstd/pull/2810 * [contrib][linux] Fix `-Wundef` inside Linux kernel tree by @solbjorn in https://github.com/facebook/zstd/pull/2802 * [contrib][linux-kernel] Add standard warnings and `-Werror` to CI by @terrelln in https://github.com/facebook/zstd/pull/2803 * Add AIX support in Makefile by @Helflym in https://github.com/facebook/zstd/pull/2747 * Limit train samples by @stanjo74 in https://github.com/facebook/zstd/pull/2809 * [multiple-ddicts] Fix `NULL` checks by @terrelln in https://github.com/facebook/zstd/pull/2817 * [ldm] Fix `ZSTD_c_ldmHashRateLog` bounds check by @terrelln in https://github.com/facebook/zstd/pull/2819 * [binary-tree] Fix underflow of `nbCompares` by @terrelln in https://github.com/facebook/zstd/pull/2820 * Enhance streaming_compression examples. by @marxin in https://github.com/facebook/zstd/pull/2813 * Pipelined Implementation of `ZSTD_dfast` by @felixhandte in https://github.com/facebook/zstd/pull/2774 * Fix a C89 error in msvc by @animalize in https://github.com/facebook/zstd/pull/2800 * [asm] Switch to C style comments by @terrelln in https://github.com/facebook/zstd/pull/2825 * Support thread pool section in HTML documentation. by @marxin in https://github.com/facebook/zstd/pull/2822 * Reduce size of `dctx` by reutilizing dst buffer by @binhdvo in https://github.com/facebook/zstd/pull/2751 * [lazy] Speed up compilation times by @terrelln in https://github.com/facebook/zstd/pull/2828 * separate compression level tables into their own file by @Cyan4973 in https://github.com/facebook/zstd/pull/2830 * minor : change build macro to `ZSTD_DECODER_INTERNAL_BUFFER` by @Cyan4973 in https://github.com/facebook/zstd/pull/2829 * Fix oss fuzz test error by @binhdvo in https://github.com/facebook/zstd/pull/2837 * Move mingw tests from appveyor to github actions by @binhdvo in https://github.com/facebook/zstd/pull/2838 * Improvements to verbose mode output by @Svetlitski-FB in https://github.com/facebook/zstd/pull/2839 * Use unused functions to appease Visual Studio by @senhuang42 in https://github.com/facebook/zstd/pull/2846 * Backport zstd patch from LKML by @terrelln in https://github.com/facebook/zstd/pull/2849 * Fix fullbench CI failure by @binhdvo in https://github.com/facebook/zstd/pull/2851 * Fix Determinism Bug: Avoid Reducing Indices to Reserved Values by @felixhandte in https://github.com/facebook/zstd/pull/2850 * `ZSTD_copy16()` uses ZSTD_memcpy() by @animalize in https://github.com/facebook/zstd/pull/2836 * Display command line parameters with concrete values in verbose mode by @Svetlitski-FB in https://github.com/facebook/zstd/pull/2847 * Reduce function size in fast & dfast by @terrelln in https://github.com/facebook/zstd/pull/2863 * [linux-kernel] Don't inline function in `zstd_opt.c` by @terrelln in https://github.com/facebook/zstd/pull/2864 * Remove executable flag from GNU_STACK segment by @ko-zu in https://github.com/facebook/zstd/pull/2857 * [linux-kernel] Don't add `-O3` to `CFLAGS` by @terrelln in https://github.com/facebook/zstd/pull/2866 * Support Swift Package Manager by @cntrump in https://github.com/facebook/zstd/pull/2858 * Determinism: Avoid Mapping Window into Reserved Indices during Reduction by @felixhandte in https://github.com/facebook/zstd/pull/2869 * Clarify documentation for `-c` by @binhdvo in https://github.com/facebook/zstd/pull/2883 * Fix build for cygwin/bsd by @binhdvo in https://github.com/facebook/zstd/pull/2882 * Move visual studio tests from per-release to per-PR by @senhuang42 in https://github.com/facebook/zstd/pull/2845 * Fix SPM warning: umbrella header for module 'libzstd' does not include header 'xxx.h' by @cntrump in https://github.com/facebook/zstd/pull/2872 * Add detection when compiling with Clang and Ninja under Windows by @jannkoeker in https://github.com/facebook/zstd/pull/2877 * [contrib][pzstd] Fix build issue with gcc-5 by @terrelln in https://github.com/facebook/zstd/pull/2889 * [bmi2] Add `lzcnt` and `bmi` target attributes by @terrelln in https://github.com/facebook/zstd/pull/2888 * [test] Test that the exec-stack bit isn't set on libzstd.so by @terrelln in https://github.com/facebook/zstd/pull/2886 * Solve the bug of extra output newline character by @15596858998 in https://github.com/facebook/zstd/pull/2876 * [zdict] Remove `ZDICT_CONTENTSIZE_MIN` restriction for `ZDICT_finalizeDictionary` by @terrelln in https://github.com/facebook/zstd/pull/2887 * Explicitly hide static symbols by @skitt in https://github.com/facebook/zstd/pull/2501 * Makefile: sort all wildcard file list expansions by @kanavin in https://github.com/facebook/zstd/pull/2895 * merge #2501 by @Cyan4973 in https://github.com/facebook/zstd/pull/2894 * Makefile: fix build for mingw by @sapiippo in https://github.com/facebook/zstd/pull/2687 * [CircleCI] Fix short-tests-0 by @terrelln in https://github.com/facebook/zstd/pull/2892 * Zstandard compiles and run on `m68k` cpus by @Cyan4973 in https://github.com/facebook/zstd/pull/2896 * Improve zstd_opt build speed and size by @terrelln in https://github.com/facebook/zstd/pull/2898 * [CI] Add `cmake` windows build by @terrelln in https://github.com/facebook/zstd/pull/2900 * Disable Multithreading in CMake Builds for Android by @felixhandte in https://github.com/facebook/zstd/pull/2899 * Avoid Using Deprecated Functions in Deprecated Code by @felixhandte in https://github.com/facebook/zstd/pull/2897 * [asm] Share portability macros and restrict ASM further by @terrelln in https://github.com/facebook/zstd/pull/2893 * fixbug CLI's -D fails when the argument is not a regular file by @15596858998 in https://github.com/facebook/zstd/pull/2890 * Apply `FORCE_MEMORY_ACCESS=1` to legacy by @Hello71 in https://github.com/facebook/zstd/pull/2907 * [lib] Fix libzstd.pc for lib-mt builds by @ericonr in https://github.com/facebook/zstd/pull/2659 * Imply `-q` when stderr is not a tty by @binhdvo in https://github.com/facebook/zstd/pull/2884 * Fix Up #2659; Build `libzstd.pc` Whenever Building the Lib on Unix by @felixhandte in https://github.com/facebook/zstd/pull/2912 * Remove possible `NULL` pointer addition by @terrelln in https://github.com/facebook/zstd/pull/2916 * updated `xxHash` to latest `v0.8.1` by @Cyan4973 in https://github.com/facebook/zstd/pull/2914 * Reject Irregular Dictionary Files by @felixhandte in https://github.com/facebook/zstd/pull/2910 * `x32` compatibility by @Cyan4973 in https://github.com/facebook/zstd/pull/2922 * typo: Small spelling mistake in example by @IAL32 in https://github.com/facebook/zstd/pull/2923 * add test case by @15596858998 in https://github.com/facebook/zstd/pull/2905 * Stagger Stepping in Negative Levels by @felixhandte in https://github.com/facebook/zstd/pull/2921 * Fix performance degradation with `-m32` by @binhdvo in https://github.com/facebook/zstd/pull/2926 * Reduce tables to 8bit by @nolange in https://github.com/facebook/zstd/pull/2930 * simplify SSE implementation of row_lazy match finder by @Cyan4973 in https://github.com/facebook/zstd/pull/2929 * Allow user to specify memory limit for dictionary training by @embg in https://github.com/facebook/zstd/pull/2925 * fixed incorrect rowlog initialization by @Cyan4973 in https://github.com/facebook/zstd/pull/2931 * rebalance lazy compression levels by @Cyan4973 in https://github.com/facebook/zstd/pull/2934 ### New Contributors * @dnelson-1901 made their first contribution in https://github.com/facebook/zstd/pull/2657 * @TrianglesPCT made their first contribution in https://github.com/facebook/zstd/pull/2653 * @binhdvo made their first contribution in https://github.com/facebook/zstd/pull/2693 * @wolfpld made their first contribution in https://github.com/facebook/zstd/pull/2654 * @aqrit made their first contribution in https://github.com/facebook/zstd/pull/2681 * @gauthamkrishna9991 made their first contribution in https://github.com/facebook/zstd/pull/2700 * @luisdallos made their first contribution in https://github.com/facebook/zstd/pull/2714 * @danlark1 made their first contribution in https://github.com/facebook/zstd/pull/2689 * @heitbaum made their first contribution in https://github.com/facebook/zstd/pull/2655 * @makise-homura made their first contribution in https://github.com/facebook/zstd/pull/2725 * @koalabearguo made their first contribution in https://github.com/facebook/zstd/pull/2707 * @jonringer made their first contribution in https://github.com/facebook/zstd/pull/2724 * @eli-schwartz made their first contribution in https://github.com/facebook/zstd/pull/2746 * @abxhr made their first contribution in https://github.com/facebook/zstd/pull/2798 * @solbjorn made their first contribution in https://github.com/facebook/zstd/pull/2790 * @nolange made their first contribution in https://github.com/facebook/zstd/pull/2805 * @3nids made their first contribution in https://github.com/facebook/zstd/pull/2810 * @Helflym made their first contribution in https://github.com/facebook/zstd/pull/2747 * @stanjo74 made their first contribution in https://github.com/facebook/zstd/pull/2809 * @Svetlitski-FB made their first contribution in https://github.com/facebook/zstd/pull/2839 * @cntrump made their first contribution in https://github.com/facebook/zstd/pull/2858 * @rex4539 made their first contribution in https://github.com/facebook/zstd/pull/2856 * @jannkoeker made their first contribution in https://github.com/facebook/zstd/pull/2877 * @yoniko made their first contribution in https://github.com/facebook/zstd/pull/2885 * @15596858998 made their first contribution in https://github.com/facebook/zstd/pull/2876 * @kanavin made their first contribution in https://github.com/facebook/zstd/pull/2895 * @sapiippo made their first contribution in https://github.com/facebook/zstd/pull/2687 * @supperPants made their first contribution in https://github.com/facebook/zstd/pull/2891 * @Hello71 made their first contribution in https://github.com/facebook/zstd/pull/2907 * @ericonr made their first contribution in https://github.com/facebook/zstd/pull/2659 * @IAL32 made their first contribution in https://github.com/facebook/zstd/pull/2923 * @embg made their first contribution in https://github.com/facebook/zstd/pull/2925 **Full Changelog**: https://github.com/facebook/zstd/compare/v1.5.0...v1.5.1 `v1.5.0` is a major release featuring large performance improvements as well as API changes. # Performance ## Improved Middle-Level Compression Speed 1.5.0 introduces a new default match finder for the compression strategies `greedy`, `lazy`, and `lazy2`, (which map to levels 5-12 for inputs larger than 256K). The optimization brings a massive improvement in compression speed with slight perturbations in compression ratio (< 0.5%) and equal or decreased memory usage. Benchmarked with gcc, on an i9-9900K: | level | `silesia.tar` speed delta | `enwik7` speed delta | |--------|-----------|------------| | 5 | +25% | +25% | | 6 | +50% | +50% | | 7 | +40% | +40% | | 8 | +40% | +50% | | 9 | +50% | +65% | | 10 | +65% | +80% | | 11 | +85% | +105% | | 12 | +110% | +140% | On heavily loaded machines with significant cache contention, we have internally measured _even larger gains_: 2-3x+ speed at levels 5-7. 🚀 The biggest gains are achieved on files typically larger than 128KB. On files smaller than 16KB, by default we revert back to the legacy match finder which becomes the faster one. This default policy can be overriden manually: the new match finder can be forcibly enabled with the advanced parameter `ZSTD_c_useRowMatchFinder`, or through the CLI option `--[no-]row-match-finder`. Note: only CPUs that support `SSE2` realize the full extent of this improvement. ## Improved High-Level Compression Ratio Improving compression ratio via block splitting is now enabled by default for high compression levels (16+). The amount of benefit varies depending on the workload. Compressing archives comprised of heavily differing files will see more improvement than compression of single files that don’t vary much entropically (like text files/enwik). At levels 16+, we observe no measurable regression to compression speed. **level 22 compression** | file | ratio 1.4.9 | ratio 1.5.0 | ratio % delta | |-----|---------|--------|-------| | silesia.tar | 4.021 | 4.041 | +0.49% | | calgary.tar | 3.646 | 3.672 | +0.71% | | enwik7 | 3.579 | 3.579 | +0.0% | The block splitter can be forcibly enabled on lower compression levels as well with the advanced parameter `ZSTD_c_splitBlocks`. When forcibly enabled at lower levels, speed regressions can become more notable. Additionally, since more compressed blocks may be produced, decompression speed on these blobs may also see small regressions. ## Faster Decompression Speed The decompression speed of data compressed with large window settings (such as `--long` or `--ultra`) has been significantly improved in this version. The gains vary depending on compiler brand and version, with `clang` generally benefiting the most. The following benchmark was measured by compressing `enwik9` at level `--ultra -22` (with a 128 MB window size) on a core i7-9700K. | Compiler version | D. Speed improvement | | --- | --- | | gcc-7 | +15% | | gcc-8 | +10 % | | gcc-9 | +5% | | gcc-10 | +1% | | clang-6 | +21% | | clang-7 | +16% | | clang-8 | +16% | | clang-9 | +18% | | clang-10 | +16% | | clang-11 | +15% | Average decompression speed for “normal” payload is slightly improved too, though the impact is less impressive. Once again, mileage varies depending on exact compiler version, payload, and even compression level. In general, a majority of scenarios see benefits ranging from +1 to +9%. There are also a few outliers here and there, from -4% to +13%. The average gain across all these scenarios stands at ~+4%. # Library Updates ## Dynamic Library Supports Multithreading by Default It was already possible to compile `libzstd` with multithreading support. But it was an active operation. By default, the `make` build script would build `libzstd` as a single-thread-only library. This changes in `v1.5.0`. Now the dynamic library (typically `libzstd.so.1` on Linux) supports multi-threaded compression by default. Note that this property is not extended to the static library (typically `libzstd.a` on Linux) because doing so would have impacted the build script of existing client applications (requiring them to add `-pthread` to their recipe), thus potentially breaking their build. In order to avoid this disruption, the static library remains single-threaded by default. Luckily, this build disruption does not extend to the dynamic library, which can be built with multi-threading support while existing applications linking to `libzstd.so` and expecting only single-thread capabilities will be none the wiser, and remain completely unaffected. The idea is that starting from `v1.5.0`, applications can _expect_ the dynamic library to support multi-threading should they need it, which will progressively lead to increased adoption of this capability overtime. That being said, since the locally deployed dynamic library may, or may not, support multi-threading compression, depending on local build configuration, it’s always better to check this capability at runtime. For this goal, it’s enough to check the return value when changing parameter `ZSTD_c_nbWorkers` , and if it results in an error, then multi-threading is not supported. _Q: What if I prefer to keep the libraries in single-thread mode only ?_ The target `make lib-nomt` will ensure this outcome. _Q: Actually, I want both static and dynamic library versions to support multi-threading !_ The target `make lib-mt` will generate this outcome. ## Promotions to Stable Moving up to the higher digit `1.5` signals an opportunity to extend the _stable_ portion of `zstd` public API. This update is relatively minor, featuring only a few non-controversial newcomers. `ZSTD_defaultCLevel()` indicates which level is default (applied when selecting level `0`). It completes existing `ZSTD_minCLevel()` and `ZSTD_maxCLevel()`. Similarly, `ZSTD_getDictID_fromCDict()` is a straightforward equivalent to already promoted `ZSTD_getDictID_fromDDict()`. ## Deprecations [Zstd-1.4.0](https://github.com/facebook/zstd/releases/tag/v1.4.0) stabilized a new [advanced API](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L238) which allows users to pass advanced parameters to zstd. We’re now deprecating all the old experimental APIs that are subsumed by the new advanced API. They will be considered for removal in the next Zstd major release zstd-1.6.0. Note that only experimental symbols are impacted. Stable functions, like `ZSTD_initCStream()`, remain fully supported. The deprecated functions are listed below, together with the migration. All the suggested migrations are stable APIs, meaning that once you migrate, the API will be supported forever. See the documentation for the deprecated functions for more details on how to migrate. - Functions that migrate to `ZSTD_compress2()` with parameter setters: * `ZSTD_compress_advanced()`: Use [`ZSTD_CCtx_setParameter()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L458-L469). * `ZSTD_compress_usingCDict_advanced()`: Use [`ZSTD_CCtx_setParameter()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L458-L469) and [`ZSTD_CCtx_refCDict()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L960-L972). - Functions that migrate to `ZSTD_compressStream()` or `ZSTD_compressStream2()` with parameter setters: * `ZSTD_initCStream_srcSize()`: Use [`ZSTD_CCtx_setPledgedSrcSize()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L471-L486). * `ZSTD_initCStream_usingDict()`: Use [`ZSTD_CCtx_loadDictionary()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L941-L958). * `ZSTD_initCStream_usingCDict()`: Use [`ZSTD_CCtx_refCDict()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L960-L972). * `ZSTD_initCStream_advanced()`: Use [`ZSTD_CCtx_setParameter()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L458-L469). * `ZSTD_initCStream_usingCDict_advanced()`: Use [`ZSTD_CCtx_setParameter()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L458-L469) and [`ZSTD_CCtx_refCDict()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L960-L972). * `ZSTD_resetCStream()`: Use [`ZSTD_CCtx_reset()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L494-L508) and [`ZSTD_CCtx_setPledgedSrcSize()`](https://github.com/facebook/zstd/blob/705a62b612151cff06f453bc3452b9e99088a574/lib/zstd.h#L471-L486). - Functions that are deprecated without replacement. We don’t expect any users of these functions. Please open an issue if you use these and have questions about how to migrate. * `ZSTD_compressBegin_advanced()` * `ZSTD_compressBegin_usingCDict_advanced()` ## Header File Locations Zstd has slightly re-organized the library layout to move all public headers to the top level `lib/` directory. This is for consistency, so all public headers are in `lib/` and all private headers are in a sub-directory. If you build zstd from source, this may affect your build system. - `lib/common/zstd_errors.h` has moved to `lib/zstd_errors.h`. - `lib/dictBuilder/zdict.h` has moved to `lib/zdict.h`. ## Single-File Library We have moved the scripts in `contrib/single_file_libs` to `build/single_file_libs`. These scripts, originally contributed by @cwoffenden, produce a single compilation-unit amalgamation of the zstd library, which can be convenient for integrating Zstandard into other source trees. This move reflects a commitment on our part to support this tool and this pattern of using zstd going forward. ## Windows Release Artifact Format We are slightly changing the format of the Windows release `.zip` files, to match our other release artifacts. The `.zip` files now bundle everything in a single folder whose name matches the archive name. The contents of that folder exactly match what was previously included in the root of the archive. ## Signed Releases We have created a [signing key](http://keys.gnupg.net/pks/lookup?op=get&search=0xEF8FE99528B52FFD) for the Zstandard project. This release and all future releases will be signed by this key. See #2520 for discussion. # Changelog - api: Various functions promoted from experimental to stable API: ([#2579](https://github.com/facebook/zstd/pull/2579)-[#2581](https://github.com/facebook/zstd/pull/2581), [@senhuang42](https://github.com/senhuang42)) * `ZSTD_defaultCLevel()` * `ZSTD_getDictID_fromCDict()` - api: Several experimental functions have been deprecated and will emit a compiler warning ([#2582](https://github.com/facebook/zstd/pull/2582), [@senhuang42](https://github.com/senhuang42)) * `ZSTD_compress_advanced()` * `ZSTD_compress_usingCDict_advanced()` * `ZSTD_compressBegin_advanced()` * `ZSTD_compressBegin_usingCDict_advanced()` * `ZSTD_initCStream_srcSize()` * `ZSTD_initCStream_usingDict()` * `ZSTD_initCStream_usingCDict()` * `ZSTD_initCStream_advanced()` * `ZSTD_initCStream_usingCDict_advanced()` * `ZSTD_resetCStream()` - api: `ZSTDMT_NBWORKERS_MAX` reduced to 64 for 32-bit environments ([#2643](https://github.com/facebook/zstd/pull/2643), [@Cyan4973](https://github.com/Cyan4973)) - perf: Significant speed improvements for middle compression levels ([#2494](https://github.com/facebook/zstd/pull/2494), [@senhuang42](https://github.com/senhuang42) & [@terrelln](https://github.com/terrelln)) - perf: Block splitter to improve compression ratio, enabled by default for high compression levels ([#2447](https://github.com/facebook/zstd/pull/2447), [@senhuang42](https://github.com/senhuang42)) - perf: Decompression loop refactor, speed improvements on `clang` and for `--long` modes ([#2614](https://github.com/facebook/zstd/pull/2614) [#2630](https://github.com/facebook/zstd/pull/2630), [@Cyan4973](https://github.com/Cyan4973)) - perf: Reduced stack usage during compression and decompression entropy stage ([#2522](https://github.com/facebook/zstd/pull/2522) [#2524](https://github.com/facebook/zstd/pull/2524), [@terrelln](https://github.com/terrelln)) - bug: Make the number of physical CPU cores detection more robust ([#2517](https://github.com/facebook/zstd/pull/2517), [@PaulBone](https://github.com/PaulBone)) - bug: Improve setting permissions of created files ([#2525](https://github.com/facebook/zstd/pull/2525), [@felixhandte](https://github.com/felixhandte)) - bug: Fix large dictionary non-determinism ([#2607](https://github.com/facebook/zstd/pull/2607), [@terrelln](https://github.com/terrelln)) - bug: Fix various dedicated dictionary search bugs ([#2540](https://github.com/facebook/zstd/pull/2540) [#2586](https://github.com/facebook/zstd/pull/2586), [@senhuang42](https://github.com/senhuang42) [@felixhandte](https://github.com/felixhandte)) - bug: Fix non-determinism test failures on Linux i686 ([#2606](https://github.com/facebook/zstd/pull/2606), [@terrelln](https://github.com/terrelln)) - bug: Fix UBSAN error in decompression ([#2625](https://github.com/facebook/zstd/pull/2625), [@terrelln](https://github.com/terrelln)) - bug: Fix superblock compression divide by zero bug ([#2592](https://github.com/facebook/zstd/pull/2592), [@senhuang42](https://github.com/senhuang42)) - bug: Ensure `ZSTD_estimateCCtxSize*()` monotonically increases with compression level ([#2538](https://github.com/facebook/zstd/pull/2538), [@senhuang42](https://github.com/senhuang42)) - doc: Improve `zdict.h` dictionary training API documentation ([#2622](https://github.com/facebook/zstd/pull/2622), [@terrelln](https://github.com/terrelln)) - doc: Note that public `ZSTD_free*()` functions accept NULL pointers ([#2521](https://github.com/facebook/zstd/pull/2521), [@animalize](https://github.com/animalize)) - doc: Add style guide docs for open source contributors ([#2626](https://github.com/facebook/zstd/pull/2626), [@Cyan4973](https://github.com/Cyan4973)) - tests: Better regression test coverage for different dictionary modes ([#2559](https://github.com/facebook/zstd/pull/2559), [@senhuang42](https://github.com/senhuang42)) - tests: Better test coverage of index reduction ([#2603](https://github.com/facebook/zstd/pull/2603), [@terrelln](https://github.com/terrelln)) - tests: OSS-Fuzz coverage for seekable format ([#2617](https://github.com/facebook/zstd/pull/2617), [@senhuang42](https://github.com/senhuang42)) - tests: Test coverage for ZSTD threadpool API ([#2604](https://github.com/facebook/zstd/pull/2604), [@senhuang42](https://github.com/senhuang42)) - build: Dynamic library built multithreaded by default ([#2584](https://github.com/facebook/zstd/pull/2584), [@senhuang42](https://github.com/senhuang42)) - build: Move `zstd_errors.h` and `zdict.h` to `lib/` root ([#2597](https://github.com/facebook/zstd/pull/2597), [@terrelln](https://github.com/terrelln)) - build: Single file library build script moved to `build/` directory ([#2618](https://github.com/facebook/zstd/pull/2618), [@felixhandte](https://github.com/felixhandte)) - build: Allow `ZSTDMT_JOBSIZE_MIN` to be configured at compile-time, reduce default to 512KB ([#2611](https://github.com/facebook/zstd/pull/2611), [@Cyan4973](https://github.com/Cyan4973)) - build: Fixed Meson build ([#2548](https://github.com/facebook/zstd/pull/2548), [@SupervisedThinking](https://github.com/SupervisedThinking) & [@kloczek](https://github.com/kloczek)) - build: `ZBUFF_*()` is no longer built by default ([#2583](https://github.com/facebook/zstd/pull/2583), [@senhuang42](https://github.com/senhuang42)) - build: Fix excessive compiler warnings with clang-cl and CMake ([#2600](https://github.com/facebook/zstd/pull/2600), [@nickhutchinson](https://github.com/nickhutchinson)) - build: Detect presence of `md5` on Darwin ([#2609](https://github.com/facebook/zstd/pull/2609), [@felixhandte](https://github.com/felixhandte)) - build: Avoid SIGBUS on armv6 ([#2633](https://github.com/facebook/zstd/pull/2633), @bmwiedmann) - cli: `--progress` flag added to always display progress bar ([#2595](https://github.com/facebook/zstd/pull/2595), [@senhuang42](https://github.com/senhuang42)) - cli: Allow reading from block devices with `--force` ([#2613](https://github.com/facebook/zstd/pull/2613), [@felixhandte](https://github.com/felixhandte)) - cli: Fix CLI filesize display bug ([#2550](https://github.com/facebook/zstd/pull/2550), [@Cyan4973](https://github.com/Cyan4973)) - cli: Fix windows CLI `--filelist` end-of-line bug ([#2620](https://github.com/facebook/zstd/pull/2620), [@Cyan4973](https://github.com/Cyan4973)) - contrib: Various fixes for linux kernel patch ([#2539](https://github.com/facebook/zstd/pull/2539), [@terrelln](https://github.com/terrelln)) - contrib: Seekable format - Decompression hanging edge case fix ([#2516](https://github.com/facebook/zstd/pull/2516), [@senhuang42](https://github.com/senhuang42)) - contrib: Seekable format - New seek table-only API ([#2113](https://github.com/facebook/zstd/pull/2113) [#2518](https://github.com/facebook/zstd/pull/2518), [@mdittmer](https://github.com/mdittmer) [@Cyan4973](https://github.com/Cyan4973)) - contrib: Seekable format - Fix seek table descriptor check when loading ([#2534](https://github.com/facebook/zstd/pull/2534), [@foxeng](https://github.com/foxeng)) - contrib: Seekable format - Decompression fix for large offsets, ([#2594](https://github.com/facebook/zstd/pull/2594), [@azat](https://github.com/azat)) - misc: Automatically published release tarballs available on Github ([#2535](https://github.com/facebook/zstd/pull/2535), [@felixhandte](https://github.com/felixhandte)) This is an incremental release which includes various improvements and bug-fixes. ## >2x Faster Long Distance Mode Long Distance Mode (LDM) `--long` just got a whole lot faster thanks to optimizations by @mpu in #2483! These optimizations preserve the compression ratio but drastically speed up compression. It is especially noticeable in multithreaded mode, because the long distance match finder is not parallelized. Benchmarking with `zstd -T0 -1 --long=31` on an Intel I9-9900K at 3.2 GHz we see: |File |v1.4.8 MB/s |v1.4.9 MB/s |Improvement | |--- |--- |--- |--- | |silesia.tar |308 |692 |125% | |linux-versions* |312 |667 |114% | |enwik9 |294 |747 |154% | \* `linux-versions` is a concatenation of the linux 4.0, 5.0, and 5.10 git archives. ## New Experimental Decompression Feature: `ZSTD_d_refMultipleDDicts` If the advanced parameter `ZSTD_d_refMultipleDDicts` is enabled, then multiple calls to `ZSTD_refDDict()` will be honored in the corresponding `DCtx`. Example usage: ``` ZSTD_DCtx* dctx = ZSTD_createDCtx(); ZSTD_DCtx_setParameter(dctx, ZSTD_d_refMultipleDDicts, ZSTD_rmd_refMultipleDDicts); ZSTD_DCtx_refDDict(dctx, ddict1); ZSTD_DCtx_refDDict(dctx, ddict2); ZSTD_DCtx_refDDict(dctx, ddict3); ... ZSTD_decompress... ``` Decompression of multiple frames, each with their own `dictID`, is now possible with a single `ZSTD_decompress` call. As long as the `dictID` from each frame header references one of the `dictID`s within the `DCtx`, then the corresponding dictionary will be used to decompress that particular frame. Note that this feature is disabled with a statically-allocated `DCtx`. ## Changelog * bug: Use `umask()` to Constrain Created File Permissions (#2495, @felixhandte) * bug: Make Simple Single-Pass Functions Ignore Advanced Parameters (#2498, @terrelln) * api: Add (De)Compression Tracing Functionality (#2482, @terrelln) * api: Support References to Multiple DDicts (#2446, @senhuang42) * api: Add Function to Generate Skippable Frame (#2439, @senhuang42) * perf: New Algorithms for the Long Distance Matcher (#2483, @mpu) * perf: Performance Improvements for Long Distance Matcher (#2464, @mpu) * perf: Don't Shrink Window Log when Streaming with a Dictionary (#2451, @terrelln) * cli: Fix `--output-dir-mirror`'s Rejection of `..`-Containing Paths (#2512, @felixhandte) * cli: Allow Input From Console When `-f`/`--force` is Passed (#2466, @felixhandte) * cli: Improve Help Message (#2500, @senhuang42) * tests: Avoid Using `stat -c` on NetBSD (#2513, @felixhandte) * tests: Correctly Invoke md5 Utility on NetBSD (#2492, @niacat) * tests: Remove Flaky Tests (#2455, #2486, #2445, @Cyan4973) * build: Zstd CLI Can Now be Linked to Dynamic `libzstd` (#2457, #2454 @Cyan4973) * build: Avoid Using Static-Only Symbols (#2504, @skitt) * build: Fix Fuzzer Compiler Detection & Update UBSAN Flags (#2503, @terrelln) * build: Explicitly Hide Static Symbols (#2501, @skitt) * build: CMake: Enable Only C for lib/ and programs/ Projects (#2498, @concatime) * build: CMake: Use `configure_file()` to Create the `.pc` File (#2462, @lazka) * build: Add Guards for `_LARGEFILE_SOURCE` and `_LARGEFILE64_SOURCE` (#2444, @indygreg) * build: Improve `zlibwrapper` Makefile (#2437, @Cyan4973) * contrib: Add `recover_directory` Program (#2473, @terrelln) * doc: Change License Year to 2021 (#2452 & #2465, @terrelln & @senhuang42) * doc: Fix Typos (#2459, @ThomasWaldmann) This is a minor hotfix for `v1.4.7`, where an internal buffer unalignment bug was detected by @bmwiedemann . The issue is of no consequence for `x64` and `arm64` targets, but could become a problem for cpus relying on strict alignment, such as `mips` or older `arm` designs. Additionally, some targets, like 32-bit `x86` cpus, do not care much about alignment, but the code does, and will detect the misalignment and return an error code. Some other less common platforms, such as `s390x`, also seem to trigger the same issue. While it's a minor fix, this update is nonetheless recommended. __Note__ : this version features a minor bug, which can be present on systems others than `x64` and `arm64`. Update `v1.4.8` is recommended for all other platforms. `v1.4.7` unleashes several months of improvements across many axis, from performance to various fixes, to new capabilities, of which a few are highlighted below. It’s a recommended upgrade. (Note: if you ever wondered what happened to `v1.4.6`, it’s an internal release number reserved for synchronization with Linux Kernel) ## Improved `--long` mode `--long` mode makes it possible to analyze vast quantities of data in reasonable time and memory budget. The `--long` mode algorithm runs on top of the regular match finder, and both contribute to the final compressed outcome. However, the fact that these 2 stages were working independently resulted in minor discrepancies at highest compression levels, where the cost of each decision must be carefully monitored. For this reason, in situations where the input is not a good fit for `--long` mode (no large repetition at long distance), enabling it *could* reduce compression performance, even if by very little, compared to not enabling it (at high compression levels). This situation made it more difficult to "just always enable" the `--long` mode by default. This is fixed in this version. For compression levels 16 and up, usage of `--long` will now never regress compared to compression without `--long`. This property made it possible to ramp up `--long` mode contribution to the compression mix, improving its effectiveness. The compression ratio improvements are most notable when `--long` mode is actually useful. In particular, `--patch-from` (which implicitly relies on `--long`) shows excellent gains from the improvements. We present some brief results [here](https://github.com/facebook/zstd/wiki/Zstandard-as-a-patching-engine) (tested on Macbook Pro 16“, i9).  Since `--long` mode is now always beneficial at high compression levels, it’s now automatically enabled for any window size >= 128MB and up. ## Faster decompression of small blocks This release includes optimizations that significantly speed up decompression of small blocks and small data. The decompression speed gains will vary based on the block size according to the table below: Block Size | Decompression Speed Improvement -----------|-------------------------------- 1 KB | ~+30% 2 KB | ~+30% 4 KB | ~+25% 8 KB | ~+15% 16 KB | ~+10% 32 KB | ~+5% These optimizations come from improving the process of reading the block header, and building the Huffman and FSE decoding tables. `zstd`’s default block size is 128 KB, and at this block size the time spent decompressing the data dominates the time spent reading the block header and building the decoding tables. But, as blocks become smaller, the cost of reading the block header and building decoding tables becomes more prominent. ## CLI improvements The CLI received several noticeable upgrades with this version. To begin with, `zstd` can accept a new parameter through environment variable, `ZSTD_NBTHREADS` . It’s useful when `zstd` is called behind an application (`tar`, or a python script for example). Also, users which prefer multithreaded compression by default can now set a desired nb of threads with their environment. This setting can still be overridden on demand via command line. A new command `--output-dir-mirror` makes it possible to compress a directory containing subdirectories (typically with `-r` command) producing one compressed file per source file, and reproduce the arborescence into a selected destination directory. There are other various improvements, such as more accurate warning and error messages, full equivalence between conventions `--long-command=FILE` and `--long-command FILE`, fixed confusion risks between `stdin` and user prompt, or between console output and status message, as well as a new short execution summary when processing multiple files, cumulatively contributing to a nicer command line experience. ## New experimental features ### Shared Thread Pool By default, each compression context can be set to use a maximum nb of threads. In complex scenarios, there might be multiple compression contexts, working in parallel, and each using some nb of threads. In such cases, it might be desirable to control the _total_ nb of threads used by _all_ these compression contexts altogether. This is now possible, by making all these compression contexts share the same threadpool. This capability is expressed thanks to a new advanced compression parameter, ``ZSTD_CCtx_refThreadPool()``, contributed by @marxin. See its [documentation](https://github.com/facebook/zstd/blob/v1.4.7/lib/zstd.h#L1501) for more details. ### Faster Dictionary Compression This release introduces a new experimental dictionary compression algorithm, applicable to mid-range compression levels, employing strategies such as `ZSTD_greedy`, `ZSTD_lazy`, and `ZSTD_lazy2`. This new algorithm can be triggered by selecting the compression parameter `ZSTD_c_enableDedicatedDictSearch` during `ZSTD_CDict` creation (experimental section). Benchmarks show the new algorithm providing significant compression speed gains : Level | Hot Dict | Cold Dict ----- | -------- | --------- 5 | ~+17% | ~+30% 6 | ~+12% | ~+45% 7 | ~+13% | ~+40% 8 | ~+16% | ~+50% 9 | ~+19% | ~+65% 10 | ~+24% | ~+70% We hope it will help making mid-levels compression more attractive for dictionary scenarios. See [the documentation](https://github.com/facebook/zstd/blob/9f8b180/lib/zstd.h#L1663-L1717) for more details. Feedback is welcome! ### New Sequence Ingestion API We introduce a new entry point, `ZSTD_compressSequences()`, which makes it possible for users to define their own sequences, by whatever mechanism they prefer, and present them to this new entry point, which will generate a single `zstd`-compressed frame, based on provided sequences. So for example, users can now feed to the function an array of externally generated `ZSTD_Sequence`: `[(offset: 5, matchLength: 4, litLength: 10), (offset: 7, matchLength: 6, litLength: 3), ...]` and the function will output a zstd compressed frame based on these sequences. This experimental API has currently several limitations (and its relevant params exist in the “experimental” section). Notably, this API currently ignores any repeat offsets provided, instead always recalculating them on the fly. Additionally, there is no way to forcibly specify existence of certain zstd features, such as RLE or raw blocks. If you are interested in this new entry point, please refer to `zstd.h` for more detailed usage instructions. ## Changelog There are many other features and improvements in this release, and since we can’t highlight them all, they are listed below: - perf: stronger `--long` mode at high compression levels, by @senhuang42 - perf: stronger `--patch-from` at high compression levels, thanks to `--long` improvements - perf: faster decompression speed for small blocks, by @terrelln - perf: faster dictionary compression at medium compression levels, by @felixhandte - perf: small speed & memory usage improvements for `ZSTD_compress2()`, by @terrelln - perf: minor generic decompression speed improvements, by @helloguo - perf: improved fast compression speeds with Visual Studio, by @animalize - cli : Set nb of threads with environment variable `ZSTD_NBTHREADS`, by @senhuang42 - cli : new `--output-dir-mirror DIR` command, by @xxie24 (#2219) - cli : accept decompressing files with `*.zstd` suffix - cli : `--patch-from` can compress `stdin` when used with `--stream-size`, by @bimbashrestha (#2206) - cli : provide a condensed summary by default when processing multiple files - cli : fix : `stdin` input can no longer be confused with user prompt - cli : fix : console output no longer mixes `stdout` and status messages - cli : improve accuracy of several error messages - api : new sequence ingestion API, by @senhuang42 - api : shared thread pool: control total nb of threads used by multiple compression jobs, by @marxin - api : new `ZSTD_getDictID_fromCDict()`, by @LuAPi - api : zlibWrapper only uses public API, and is compatible with dynamic library, by @terrelln - api : fix : multithreaded compression has predictable output even in special cases (see #2327) (issue not present on cli) - api : fix : dictionary compression correctly respects dictionary compression level (see #2303) (issue not present on cli) - api : fix : return `dstSize_tooSmall` error whenever appropriate - api : fix : `ZSTD_initCStream_advanced()` with static allocation and no dictionary - build: fix cmake script when employing path including spaces, by @terrelln - build: new `ZSTD_NO_INTRINSICS` macro to avoid explicit intrinsics - build: new `STATIC_BMI2` macro for compile time detection of BMI2 on MSVC, by @Niadb (#2258) - build: improved compile-time detection of aarch64/neon platforms, by @bsdimp - build: Fix building on AIX 5.1, by @likema - build: compile paramgrill with cmake on Windows, requested by @mirh - build: install pkg-config file with CMake and MinGW, by @tonytheodore (#2183) - build: Install DLL with CMake on Windows, by @BioDataAnalysis (#2221) - build: fix : cli compilation with uclibc - misc: Improve single file library and include dictBuilder, by @cwoffenden - misc: Fix single file library compilation with Emscripten, by @yoshihitoh (#2227) - misc: Add freestanding translation script in `contrib/freestanding_lib`, by @terrelln - doc : clarify repcode updates in format specification, by @felixhandte # Zstd v1.4.5 Release Notes This is a fairly important release which includes performance improvements and new major CLI features. It also fixes a few corner cases, making it a recommended upgrade. ## Faster Decompression Speed Decompression speed has been improved again, thanks to great contributions from [@terrelln](https://github.com/terrelln). As usual, exact mileage varies depending on files and compilers. For `x64` cpus, expect a speed bump of at least +5%, and up to +10% in favorable cases. `ARM` cpus receive more benefit, with speed improvements ranging from +15% vicinity, and up to +50% for certain SoCs and scenarios (`ARM`‘s situation is more complex due to larger differences in SoC designs). For illustration, some benchmarks run on a modern `x64` platform using `zstd -b` compiled with `gcc` v9.3.0 : | |v1.4.4 |v1.4.5 | |--- |--- |--- | |silesia.tar |1568 MB/s |1653 MB/s | |--- |--- |--- | |enwik8 |1374 MB/s |1469 MB/s | |calgary.tar |1511 MB/s |1610 MB/s | Same platform, using `clang` v10.0.0 compiler : | |v1.4.4 |v1.4.5 | |--- |--- |--- | |silesia.tar |1439 MB/s |1496 MB/s | |--- |--- |--- | |enwik8 |1232 MB/s |1335 MB/s | |calgary.tar |1361 MB/s |1457 MB/s | ## Simplified integration Presuming a project needs to integrate `libzstd`'s *source code* (as opposed to linking a pre-compiled library), the `/lib` source directory can be copy/pasted into target project. Then the local build system must setup a few include directories. Some setups are automatically provided in prepared build scripts, such as `Makefile`, but any other 3rd party build system must do it on its own. This integration is now simplified, thanks to @felixhandte, by making all dependencies within `/lib` relative, meaning it’s only necessary to setup include directories for the `*.h` header files that are directly included into target project (typically `zstd.h`). Even that task can be circumvented by copy/pasting the `*.h` into already established include directories. Alternatively, if you are a fan of one-file integration strategy, @cwoffenden has extended his one-file decoder script into a full feature [one-file compression library](https://github.com/facebook/zstd/tree/dev/contrib/single_file_libs). The script [`create_single_file_library.sh`](https://github.com/facebook/zstd/blob/dev/contrib/single_file_libs/create_single_file_library.sh) will generate a file `zstd.c`, which contains all selected elements from the library (by default, compression and decompression). It’s then enough to import just `zstd.h` and the generated `zstd.c` into target project to access all included capabilities. ## `--patch-from` Zstandard CLI is introducing a new command line option `--patch-from`, which leverages existing compressors, dictionaries and long range match finder to deliver a high speed engine for producing and applying patches to files. `--patch-from` is based on dictionary compression. It will consider a previous version of a file as a dictionary, to better compress a new version of same file. This operation preserves fast `zstd` speeds at lower compression levels. To this ends, it also increases the previous maximum limit for dictionaries from 32 MB to 2 GB, and automatically uses the long range match finder when needed (though it can also be manually overruled). `--patch-from` can also be combined with multi-threading mode at a very minimal compression ratio loss. Example usage: ``` # create the patch zstd --patch-from=<oldfile> <newfile> -o <patchfile> # apply the patch zstd -d --patch-from=<oldfile> <patchfile> -o <newfile>` ``` Benchmarks: We compared `zstd` to `bsdiff`, a popular industry grade diff engine. Our test corpus were tarballs of different versions of source code from popular GitHub repositories. Specifically: ``` `repos = { # ~31mb (small file) "zstd": {"url": "https://github.com/facebook/zstd", "dict-branch": "refs/tags/v1.4.2", "src-branch": "refs/tags/v1.4.3"}, # ~273mb (medium file) "wordpress": {"url": "https://github.com/WordPress/WordPress", "dict-branch": "refs/tags/5.3.1", "src-branch": "refs/tags/5.3.2"}, # ~1.66gb (large file) "llvm": {"url": "https://github.com/llvm/llvm-project", "dict-branch": "refs/tags/llvmorg-9.0.0", "src-branch": "refs/tags/llvmorg-9.0.1"} }` ``` `--patch-from` on level 19 (with chainLog=30 and targetLength=4kb) is comparable with `bsdiff` when comparing patch sizes.  `--patch-from` greatly outperforms `bsdiff` in speed even on its slowest setting of level 19 boasting an average speedup of ~7X. `--patch-from` is >200X faster on level 1 and >100X faster (shown below) on level 3 vs `bsdiff` while still delivering patch sizes less than 0.5% of the original file size.   And of course, there is no change to the fast zstd decompression speed. _Addendum_ : After releasing `--patch-from`, we were made aware of two other popular diff engines by the community: SmartVersion and Xdelta. We ran some additional benchmarks for them and here are our primary takeaways. All three tools are excellent diff engines with clear advantages (especially in speed) over the popular bsdiff. Patch sizes for both binary and text data produced by all three are pretty comparable with Xdelta underperforming Zstd and SmartVersion only slightly [1]. For patch creation speed, Xdelta is the clear winner for text data and Zstd is the clear winner for binary data [2]. And for Patch Extraction Speed (ie. decompression), Zstd is fastest in all scenarios [3]. See [wiki](https://github.com/facebook/zstd/wiki/PatchFrom#patchfrom-vs-smartversion-vs-xdelta-for-wiki) for details. ## `--filelist=` Finally, `--filelist=` is a new CLI capability, which makes it possible to pass a list of files to operate upon from a file, as opposed to listing all target files solely on the command line. This makes it possible to prepare a list offline, save it into a file, and then provide the prepared list to `zstd`. Another advantage is that this method circumvents command line size limitations, which can become a problem when operating on very large directories (such situation can typically happen with shell expansion). In contrast, passing a very large list of filenames from within a file is free of such size limitation. ## Full List - perf: Improved decompression speed (x64 >+5%, ARM >+15%), by @terrelln - perf: Automatically downsizes `ZSTD_DCtx` when too large for too long (#2069, by @bimbashrestha) - perf: Improved fast compression speed on `aarch64` (#2040, ~+3%, by @caoyzh) - perf: Small level 1 compression speed gains (depending on compiler) - fix: Compression ratio regression on huge files (> 3 GB) using high levels (`--ultra`) and multithreading, by @terrelln - api: `ZDICT_finalizeDictionary()` is promoted to stable (#2111) - api: new experimental parameter `ZSTD_d_stableOutBuffer` (#2094) - build: Generate a single-file `libzstd` library (#2065, by [@cwoffenden](https://github.com/cwoffenden)) - build: Relative includes, no longer require `-I` flags for `zstd` lib subdirs (#2103, by @felixhandte) - build: `zstd` now compiles cleanly under `-pedantic` (#2099) - build: `zstd` now compiles with make-4.3 - build: Support `mingw` cross-compilation from Linux, by @Ericson2314 - build: Meson multi-thread build fix on windows - build: Some misc `icc` fixes backed by new ci test on travis - cli: New `--patch-from` command, create and apply patches from files, by @bimbashrestha - cli: `--filelist=` : Provide a list of files to operate upon from a file - cli: `-b` can now benchmark multiple files in decompression mode - cli: New `--no-content-size` command - cli: New `--show-default-cparams` command - misc: new diagnosis tool, `checked_flipped_bits`, in `contrib/`, by @felixhandte - misc: Extend largeNbDicts benchmark to compression - misc: experimental edit-distance match finder in `contrib/` - doc: Improved beginner `CONTRIBUTING.md` docs - doc: New issue templates for zstd

The markdown parsing is broken/disabled for release notes. Sorry about that, I'm chasing the source of a crash that's been bringing this website down for the last couple of days. ## JavaScript 1. Changes NPM packaging to workaround TypeScript resolution issues ### JavaScript 1. Add entrypoint for usage without top-level await 2. Expose bindings for `hasNewLayout()` Yoga 3.0 is a new major (breaking) version of Yoga, used by React Native 0.74. ### Highlights 1. Support for `position: static` 2. Support for `align-content: space-evenly` 3. Improvements to layout correctness 4. Yoga’s JavaScript bindings are now distributed as an ES Module 5. Fixes several crashes in Java bindings 6. Some existing Yoga APIs have been removed Learn more at https://yogalayout.dev/blog/announcing-yoga-3.0 ### JavaScript 1. Fixes`yoga-layout/wasm-sync` exporting an async entrypoint if `browser` or `node` export conditions not met We are excited to announce a new major (breaking) version of Yoga. This release contains 198 new commits from 64 contributors, and includes the first significant changes to Yoga in open-source since 2018. While there has been a [long gap in development](https://github.com/facebook/yoga/issues/1151), the React Native team believes Yoga is a critical tool in delivering the future of React, and we have resumed development of the engine. This release of Yoga is focused on: 1. Delivering the features we have shipped to React Native to standalone Yoga users 2. Updating toolchains, packaging, and build systems to make Yoga easier to consume 3. API changes to allow us to evolve the engine towards conformance Yoga continuously ships to thousands of surfaces across multiple frameworks at Meta. This version of Yoga corresponds to the version which will be included in React Native 0.73 shipping this fall. ## Flexbox gap The most significant new feature for users on an older stable release of Yoga is the addition of Flexbox gap support. This powers `gap`, `rowGap`, and `columnGap` in React Native 0.71. ```cpp // Example.cpp YGNodeStyleSetGap(node, YGGutterRow, 2.0f); ``` ```java // Example.java node.setGap(YogaGutter.ROW, 2.0f); ``` ```ts // Example.ts node.setGap(Gutter.Row, 2); ``` ## Toolchain Meta uses [Buck](https://buck.build/) across its monorepo, but we recognize that Buck has acted as a barrier to be able to use Yoga outside of Meta. Yoga no longer ships build logic for Buck to open-source. We have instead added over 20 new validation jobs to GitHub Actions to continually validate that Yoga builds correctly in common systems and scenarios where Yoga is used in OSS. New toolchain support includes: 1. A reference CMake build for Yoga and its unit tests 1. A modern Gradle build and published AARs 1. Compatibility with XCode 14.3+ 1. Compatibility with Node 16+ 1. Support for WebAssembly in both Node and browsers 1. Support for MSVC, higher warning levels, and building without exceptions ## Aiming for Conformance Our team wants to enable engineers to be able to create a single style which renders faithfully across Yoga and web. Conformance is a moving target, with browsers like Chromium regularly making behavior changes to better achieve it. This requires making behavior changes to Yoga which break existing behaviors, for better consistency with the web. In Yoga 2.0, we’ve generalized `UseLegacyStretchBehaviour` to a new [Errata API](https://github.com/facebook/yoga/issues/1247), to allow different parts of a Yoga tree to target different conformance levels. This allows rendering part of the tree to be compatible with styles written for web, with other parts compatible with styles written for older versions of Yoga. Yoga's default behavior going forward is W3C compliance. We recommend users sensitive to the change to set `YGErrataClassic,` or `YGErrataAll` if you were already setting `UseLegacyStretchBehaviour`. ```cpp // Example.cpp YGConfigRef config = YGConfigNew(); YGConfigSetErrata(config, YGErrataClassic); YGNodeRef node = YGNodeNewWithConfig(config); ``` ```java // Example.java YogaConfig config = YogaConfigFactory.create(); config.setErrata(YogaErrata.CLASSIC); YogaNode node = YogaNodeFactory.create(config); ``` ```ts // Example.ts const config = Config.create(); config.setErrata(Errata.Classic); const node = Node.create(config); ``` ## Yoga for JavaScript Yoga’s previous JavaScript bindings are not installable when using Node 12+, making them effectively unusable in today’s JavaScript ecosystem. We now ship a new package with prebuilt binaries and first-class support for TypeScript and modern bundlers. Two variants are shipped: 1. An asmjs variant for compatibility 1. A JS module with embedded WebAssembly (~50% faster) Both are about 45KB when gzipped. WebAssembly binaries must be asynchronously compiled and loaded in Chrome. In the absence of universal support for top-level await, we have made the breaking change to require explicitly asynchronously loading Yoga before using it. ```ts import {loadYoga, Align} from 'yoga-layout'; const Yoga = await loadYoga(); const node = Yoga.Node.create(); node.setAlignContent(Align.Center); ``` The previous behavior of blocking to load the binary can be replicated by importing from the `yoga-layout/sync` entrypoint, but this is not recommended for new usages, and does not allow using WebAssembly on browsers. ```ts import Yoga, {ALIGN_CENTER} from 'yoga-layout/sync'; const node = Yoga.Node.create(); node.setAlignContent(ALIGN_CENTER); ``` `yoga-layout` and `yoga-layout/sync` try to pick between `asmjs` and `WebAssembly` automatically based on the [target environment](https://webpack.js.org/guides/package-exports/#target-environment) set by your bundler, but you can choose this explicitly as well. ```ts import {loadYoga} from 'yoga-layout/wasm-async'; ``` > Note: the `yoga-layout` package requires your bundler and typechecker to configured to be able to follow the package `exports `field. ## Deprecations and removals ### YogaKit and YogaLayout ViewGroup We are deprecating, `YogaKit` and the `YogaLayout` ViewGroup. These libraries allow initegrating Yoga directly with UIKit and the Android view system, but are not widely used by Meta in production. We are instead focusing on higher-level libraries using Yoga like [Litho](https://fblitho.com/) and [React Native](https://reactnative.dev/). Because we aren’t in a place to continue development, or validate contributions, we are discontinuing development. These libraries will not receive future updates beyond the Yoga `release-v2.0` branch. ### UseLegacyStretchBehaviour The functions to manipulate `UseLegacyStretchBehaviour` have been deprecated. Previous users of the API should now set an appropriate errata level, like `YGErrataAll` to opt-out of all future conformance fixes. ### C# bindings C# bindings were contributed to the Yoga repo but have since degraded. The bindings have not had working build validation, or a consistent contributor. We have removed them from the Yoga repo, but we will continue to provide a public C ABI for others to build bindings on top of. ### Private C++ APIs Yoga’s header structure has historically allowed the inclusion of concrete internal structures like `YGStyle` or `YGNode`. We will begin to enforce that users instead rely on the public C APIs provided by `#include <yoga/Yoga.h>`. Other C++ APIs may change without notice. ```cpp // Public API (GOOD) #include <yoga/Yoga.h> YGConfigRef config = YGConfigNew(); YGConfigSetPointScaleFactor(config, 1.0f); ``` ```cpp // Private API (BAD) #include <yoga/YGConfig.h> YGConfig config{yogaLogger_}; config.pointScaleFactor = 1.0f; ``` ### C++ 11 Support Yoga now requires a compiler which supports C++ 14. This will likely be bumped to C++ 17 in a future minor release. ## How do I get it? For users who don’t want to build from source, new Yoga packages have been published to the npmjs registry, Maven Central, and CocoaPods. ```jsonc // package.json dependencies: { "yoga-layout": "^2.0.0" } ``` ```gradle // build.gradle dependencies { implementation("com.facebook.yoga:yoga:2.0.0") } ``` ```rb # Podfile pod 'Yoga', '~> 2.0.0' ``` ## Acknowledgements Yoga 2.0 contains major external contributions from [@intergalacticspacehighway](intergalacticspacehighway), [@jacobp100](https://github.com/jacobp100), [@jeetiss](https://github.com/jeetiss) and [@nicoburns](https://github.com/nicoburns). Release for Maven Central. New stable with some bug fixes around `align-content`

The markdown parsing is broken/disabled for release notes. Sorry about that, I'm chasing the source of a crash that's been bringing this website down for the last couple of days. Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1700) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1631) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1621) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1620) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1613) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1612) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1611) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1610) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1601) Consult [Changelog](https://github.com/facebook/facebook-ios-sdk/blob/main/CHANGELOG.md#1600)