=========================== Release notes for C-Blosc =========================== :Author: Francesc Alted :Contact: francesc@blosc.org :URL: http://www.blosc.org Changes from 1.9.2 to 1.9.3 =========================== - Reverted a mistake introduced in 1.7.1. At that time, bit-shuffling was enabled for typesize == 1 (i.e. strings), but the change also included byte-shuffling accidentally. This only affected performance, but in a quite bad way (a copy was needed). This has been fixed and byte-shuffling is not active when typesize == 1 anymore. Changes from 1.9.1 to 1.9.2 =========================== - Check whether Blosc is actually initialized before blosc_init(), blosc_destroy() and blosc_free_resources(). This makes the library more resistant to different initialization cycles (e.g. https://github.com/stevengj/Blosc.jl/issues/19). Changes from 1.9.0 to 1.9.1 =========================== - The internal copies when clevel=0 are made now via memcpy(). At the beginning of C-Blosc development, benchmarks where saying that the internal, multi-threaded copies inside C-Blosc were faster than memcpy(), but 6 years later, memcpy() made greats strides in terms of efficiency. With this, you should expect an slight speed advantage (10% ~ 20%) when C-Blosc is used as a replacement of memcpy() (which should not be the most common scenario out there). - Added a new DEACTIVATE_AVX2 cmake option to explicitly disable AVX2 at build-time. Thanks to James Bird. - The ``make -jN`` for parallel compilation should work now. Thanks to James Bird. Changes from 1.8.1 to 1.9.0 =========================== * New blosc_get_nthreads() function to get the number of threads that will be used internally during compression/decompression (set by already existing blosc_set_nthreads()). * New blosc_get_compressor() function to get the compressor that will be used internally during compression (set by already existing blosc_set_compressor()). * New blosc_get_blocksize() function to get the internal blocksize to be used during compression (set by already existing blosc_set_blocksize()). * Now, when the BLOSC_NOLOCK environment variable is set (to any value), the calls to blosc_compress() and blosc_decompress() will call blosc_compress_ctx() and blosc_decompress_ctx() under the hood so as to avoid the internal locks. See blosc.h for details. This allows multi-threaded apps calling the non _ctx() functions to avoid the internal locks in C-Blosc. For the not multi-threaded app though, it is in general slower to call the _ctx() functions so the use of BLOSC_NOLOCK is discouraged. * In the same vein, from now on, when the BLOSC_NTHREADS environment variable is set to an integer, every call to blosc_compress() and blosc_decompress() will call blosc_set_nthreads(BLOSC_NTHREADS) before the actuall compression/decompression process. See blosc.h for details. * Finally, if BLOSC_CLEVEL, BLOSC_SHUFFLE, BLOSC_TYPESIZE and/or BLOSC_COMPRESSOR variables are set in the environment, these will be also honored before calling blosc_compress(). * Calling blosc_init() before any other Blosc call, although recommended, is not necessary anymore. The idea is that you can use just the basic blosc_compress() and blosc_decompress() and control other parameters (nthreads, compressor, blocksize) by using environment variables (see above). Changes from 1.8.0 to 1.8.1 =========================== * Disable the use of __builtin_cpu_supports() for GCC 5.3.1 compatibility. Details in: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/ZM2L65WIZEEQHHLFERZYD5FAG7QY2OGB/ Changes from 1.7.1 to 1.8.0 =========================== * The code is (again) compatible with VS2008 and VS2010. This is important for compatibility with Python 2.6/2.7/3.3/3.4. * Introduced a new global lock during blosc_decompress() operation. As the blosc_compress() was already guarded by a global lock, this means that the compression/decompression is again thread safe. However, when using C-Blosc from multi-threaded environments, it is important to keep using the *_ctx() functions for performance reasons. NOTE: _ctx() functions will be replaced by more powerful ones in C-Blosc 2.0. Changes from 1.7.0 to 1.7.1 =========================== * Fixed a bug preventing bitshuffle to work correctly on getitem(). Now, everything with bitshuffle seems to work correctly. * Fixed the thread initialization for blosc_decompress_ctx(). Issue #158. Thanks to Chris Webers. * Fixed a bug in the blocksize computation introduced in 1.7.0. This could have been creating segfaults. * Allow bitshuffle to run on 1-byte typesizes. * New parametrization of the blocksize to be independent of the typesize. This allows a smoother speed throughout all typesizes. * lz4 and lz4hc codecs upgraded to 1.7.2 (from 1.7.0). * When calling set_nthreads() but not actually changing the number of threads in the internal pool does not teardown and setup it anymore. PR #153. Thanks to Santi Villalba. Changes from 1.6.1 to 1.7.0 =========================== * Added a new 'bitshuffle' filter so that the shuffle takes place at a bit level and not just at a byte one, which is what it does the previous 'shuffle' filter. For activating this new bit-level filter you only have to pass the symbol BLOSC_BITSHUFFLE to `blosc_compress()`. For the previous byte-level one, pass BLOSC_SHUFFLE. For disabling the shuffle, pass BLOSC_NOSHUFFLE. This is a port of the existing filter in https://github.com/kiyo-masui/bitshuffle. Thanks to Kiyo Masui for changing the license and allowing its inclusion here. * New acceleration mode for LZ4 and BloscLZ codecs that enters in operation with complevel < 9. This allows for an important boost in speed with minimal compression ratio loss. Francesc Alted. * LZ4 codec updated to 1.7.0 (r130). * PREFER_EXTERNAL_COMPLIBS cmake option has been removed and replaced by the more fine grained PREFER_EXTERNAL_LZ4, PREFER_EXTERNAL_SNAPPY and PREFER_EXTERNAL_ZLIB. In order to allow the use of the new API introduced in LZ4 1.7.0, PREFER_EXTERNAL_LZ4 has been set to OFF by default, whereas PREFER_EXTERNAL_SNAPPY and PREFER_EXTERNAL_ZLIB continues to be ON. * Implemented SSE2 shuffle support for buffers containing a number of elements which is not a multiple of (typesize * vectorsize). Jack Pappas. * Added SSE2 shuffle/unshuffle routines for types larger than 16 bytes. Jack Pappas. * 'test_basic' suite has been split in components for a much better granularity on what's a possibly failing test. Also, lots of new tests have been added. Jack Pappas. * Fixed compilation on non-Intel archs (tested on ARM). Zbyszek Szmek. * Modifyied cmake files in order to inform that AVX2 on Visual Studio is supported only in 2013 update 2 and higher. * Added a replacement for stdbool.h for Visual Studio < 2013. * blosclz codec adds Win64/Intel as a platform supporting unaligned addressing. That leads to a speed-up of 2.2x in decompression. * New blosc_get_version_string() function for retrieving the version of the c-blosc library. Useful when linking with dynamic libraries and one want to know its version. * New example (win-dynamic-linking.c) that shows how to link a Blosc DLL dynamically in run-time (Windows only). * The `context.threads_started` is initialized now when decompressing. This could cause crashes in case you decompressed before compressing (e.g. directly deserializing blosc buffers). @atchouprakov. * The HDF5 filter has been removed from c-blosc and moved into its own repo at: https://github.com/Blosc/hdf5 * The MS Visual Studio 2008 has been tested with c-blosc for ensuring compatibility with extensions for Python 2.6 and up. Changes from 1.6.0 to 1.6.1 =========================== * Support for *runtime* detection of AVX2 and SSE2 SIMD instructions. These changes make it possible to compile one single binary that runs on a system that supports SSE2 or AVX2 (or neither), so the redistribution problem is fixed (see #101). Thanks to Julian Taylor and Jack Pappas. * Added support for MinGW and TDM-GCC compilers for Windows. Thanks to yasushima-gd. * Fixed a bug in blosclz that could potentially overwrite an area beyond the output buffer. See #113. * New computation for blocksize so that larger typesizes (> 8 bytes) would benefit of much better compression ratios. Speed is not penalized too much. * New parametrization of the hash table for blosclz codec. This allows better compression in many scenarios, while slightly increasing the speed. Changes from 1.5.4 to 1.6.0 =========================== * Support for AVX2 is here! The benchmarks with a 4-core Intel Haswell machine tell that both compression and decompression are accelerated around a 10%, reaching peaks of 9.6 GB/s during compression and 26 GB/s during decompression (memcpy() speed for this machine is 7.5 GB/s for writes and 11.7 GB/s for reads). Many thanks to @littlezhou for this nice work. * Support for HPET (high precision timers) for the `bench` program. This is particularly important for microbenchmarks like bench is doing; since they take so little time to run, the granularity of a less-accurate timer may account for a significant portion of the runtime of the benchmark itself, skewing the results. Thanks to Jack Pappas. Changes from 1.5.3 to 1.5.4 =========================== * Updated to LZ4 1.6.0 (r128). * Fix resource leak in t_blosc. Jack Pappas. * Better checks during testing. Jack Pappas. * Dynamically loadable HDF5 filter plugin. Kiyo Masui. Changes from 1.5.2 to 1.5.3 =========================== * Use llabs function (where available) instead of abs to avoid truncating the result. Jack Pappas. * Use C11 aligned_alloc when it's available. Jack Pappas. * Use the built-in stdint.h with MSVC when available. Jack Pappas. * Only define the __SSE2__ symbol when compiling with MS Visual C++ and targeting x64 or x86 with the correct /arch flag set. This avoids re-defining the symbol which makes other compilers issue warnings. Jack Pappas. * Reinitializing Blosc during a call to set_nthreads() so as to fix problems with contexts. Francesc Alted. Changes from 1.5.1 to 1.5.2 =========================== * Using blosc_compress_ctx() / blosc_decompress_ctx() inside the HDF5 compressor for allowing operation in multiprocess scenarios. See: https://github.com/PyTables/PyTables/issues/412 The drawback of this quick fix is that the Blosc filter will be only able to use a single thread until another solution can be devised. Changes from 1.5.0 to 1.5.1 =========================== * Updated to LZ4 1.5.0. Closes #74. * Added the 'const' qualifier to non SSE2 shuffle functions. Closes #75. * Explicitly call blosc_init() in HDF5 blosc_filter.c, fixing a segfault. * Quite a few improvements in cmake files for HDF5 support. Thanks to Dana Robinson (The HDF Group). * Variable 'class' caused problems compiling the HDF5 filter with g++. Thanks to Laurent Chapon. * Small improvements on docstrings of c-blosc main functions. Changes from 1.4.1 to 1.5.0 =========================== * Added new calls for allowing Blosc to be used *simultaneously* (i.e. lock free) from multi-threaded environments. The new functions are: - blosc_compress_ctx(...) - blosc_decompress_ctx(...) See the new docstrings in blosc.h for how to use them. The previous API should be completely unaffected. Thanks to Christopher Speller. * Optimized copies during BloscLZ decompression. This can make BloscLZ to decompress up to 1.5x faster in some situations. * LZ4 and LZ4HC compressors updated to version 1.3.1. * Added an examples directory on how to link apps with Blosc. * stdlib.h moved from blosc.c to blosc.h as suggested by Rob Lathm. * Fix a warning for {snappy,lz4}-free compilation. Thanks to Andrew Schaaf. * Several improvements for CMakeLists.txt (cmake). * Fixing C99 compatibility warnings. Thanks to Christopher Speller. Changes from 1.4.0 to 1.4.1 =========================== * Fixed a bug in blosc_getitem() introduced in 1.4.0. Added a test for blosc_getitem() as well. Changes from 1.3.6 to 1.4.0 =========================== * Support for non-Intel and non-SSE2 architectures has been added. In particular, the Raspberry Pi platform (ARM) has been tested and all tests pass here. * Architectures requiring strict access alignment are supported as well. Due to this, arquitectures with a high penalty in accessing unaligned data (e.g. Raspberry Pi, ARMv6) can compress up to 2.5x faster. * LZ4 has been updated to r119 (1.2.0) so as to fix a possible security breach. Changes from 1.3.5 to 1.3.6 =========================== * Updated to LZ4 r118 due to a (highly unlikely) security hole. For details see: http://fastcompression.blogspot.fr/2014/06/debunking-lz4-20-years-old-bug-myth.html Changes from 1.3.4 to 1.3.5 =========================== * Removed a pointer from 'pointer from integer without a cast' compiler warning due to a bad macro definition. Changes from 1.3.3 to 1.3.4 =========================== * Fixed a false buffer overrun condition. This bug made c-blosc to fail, even if the failure was not real. * Fixed the type of a buffer string. Changes from 1.3.2 to 1.3.3 =========================== * Updated to LZ4 1.1.3 (improved speed for 32-bit platforms). * Added a new `blosc_cbuffer_complib()` for getting the compression library for a compressed buffer. Changes from 1.3.1 to 1.3.2 =========================== * Fix for compiling Snappy sources against MSVC 2008. Thanks to Mark Wiebe! * Version for internal LZ4 and Snappy are now supported. When compiled against the external libraries, this info is not available because they do not support the symbols (yet). Changes from 1.3.0 to 1.3.1 =========================== * Fixes for a series of issues with the filter for HDF5 and, in particular, a problem in the decompression buffer size that made it impossible to use the blosc_filter in combination with other ones (e.g. fletcher32). See https://github.com/PyTables/PyTables/issues/21. Thanks to Antonio Valentino for the fix! Changes from 1.2.4 to 1.3.0 =========================== A nice handful of compressors have been added to Blosc: * LZ4 (http://code.google.com/p/lz4/): A very fast compressor/decompressor. Could be thought as a replacement of the original BloscLZ, but it can behave better is some scenarios. * LZ4HC (http://code.google.com/p/lz4/): This is a variation of LZ4 that achieves much better compression ratio at the cost of being much slower for compressing. Decompression speed is unaffected (and sometimes better than when using LZ4 itself!), so this is very good for read-only datasets. * Snappy (http://code.google.com/p/snappy/): A very fast compressor/decompressor. Could be thought as a replacement of the original BloscLZ, but it can behave better is some scenarios. * Zlib (http://www.zlib.net/): This is a classic. It achieves very good compression ratios, at the cost of speed. However, decompression speed is still pretty good, so it is a good candidate for read-only datasets. With this, you can select the compression library with the new function:: int blosc_set_complib(char* complib); where you pass the library that you want to use (currently "blosclz", "lz4", "lz4hc", "snappy" and "zlib", but the list can grow in the future). You can get more info about compressors support in you Blosc build by using these functions:: char* blosc_list_compressors(void); int blosc_get_complib_info(char *compressor, char **complib, char **version); Changes from 1.2.2 to 1.2.3 =========================== - Added a `blosc_init()` and `blosc_destroy()` so that the global lock can be initialized safely. These new functions will also allow other kind of initializations/destructions in the future. Existing applications using Blosc do not need to start using the new functions right away, as long as they calling `blosc_set_nthreads()` previous to anything else. However, using them is highly recommended. Thanks to Oscar Villellas for the init/destroy suggestion, it is a nice idea! Changes from 1.2.1 to 1.2.2 =========================== - All important warnings removed for all tested platforms. This will allow less intrusiveness compilation experiences with applications including Blosc source code. - The `bench/bench.c` has been updated so that it can be compiled on Windows again. - The new web site has been set to: http://www.blosc.org Changes from 1.2 to 1.2.1 ========================= - Fixed a problem with global lock not being initialized. This affected mostly to Windows platforms. Thanks to Christoph Gohlke for finding the cure! Changes from 1.1.5 to 1.2 ========================= - Now it is possible to call Blosc simultaneously from a parent threaded application without problems. This has been solved by setting a global lock so that the different calling threads do not execute Blosc routines at the same time. Of course, real threading work is still available *inside* Blosc itself. Thanks to Thibault North. - Support for cmake is now included. Linux, Mac OSX and Windows platforms are supported. Thanks to Thibault North, Antonio Valentino and Mark Wiebe. - Fixed many compilers warnings (specially about unused variables). - As a consequence of the above, as minimal change in the API has been introduced. That is, the previous API:: void blosc_free_resources(void) has changed to:: int blosc_free_resources(void) Now, a return value of 0 means that the resources have been released successfully. If the return value is negative, then it is not guaranteed that all the resources have been freed. - Many typos were fixed and docs have been improved. The script for generating nice plots for the included benchmarks has been improved too. Thanks to Valetin Haenel. Changes from 1.1.4 to 1.1.5 =========================== - Fix compile error with msvc compilers (Christoph Gohlke) Changes from 1.1.3 to 1.1.4 =========================== - Redefinition of the BLOSC_MAX_BUFFERSIZE constant as (INT_MAX - BLOSC_MAX_OVERHEAD) instead of just INT_MAX. This prevents to produce outputs larger than INT_MAX, which is not supported. - `exit()` call has been replaced by a ``return -1`` in blosc_compress() when checking for buffer sizes. Now programs will not just exit when the buffer is too large, but return a negative code. - Improvements in explicit casts. Blosc compiles without warnings (with GCC) now. - Lots of improvements in docs, in particular a nice ascii-art diagram of the Blosc format (Valentin Haenel). - Improvements to the plot-speeds.py (Valentin Haenel). - [HDF5 filter] Adapted HDF5 filter to use HDF5 1.8 by default (Antonio Valentino). - [HDF5 filter] New version of H5Z_class_t definition (Antonio Valentino). Changes from 1.1.2 to 1.1.3 =========================== - Much improved compression ratio when using large blocks (> 64 KB) and high compression levels (> 6) under some circumstances (special data distribution). Closes #7. Changes from 1.1.1 to 1.1.2 =========================== - Fixes for small typesizes (#6 and #1 of python-blosc). Changes from 1.1 to 1.1.1 ========================= - Added code to avoid calling blosc_set_nthreads more than necessary. That will improve performance up to 3x or more, specially for small chunksizes (< 1 MB). Changes from 1.0 to 1.1 ======================= - Added code for emulating pthreads API on Windows. No need to link explicitly with pthreads lib on Windows anymore. However, performance is a somewhat worse because the new emulation layer does not support the `pthread_barrier_wait()` call natively. But the big improvement in installation easiness is worth this penalty (most specially on 64-bit Windows, where pthreads-win32 support is flaky). - New BLOSC_MAX_BUFFERSIZE, BLOSC_MAX_TYPESIZE and BLOSC_MAX_THREADS symbols are available in blosc.h. These can be useful for validating parameters in clients. Thanks to Robert Smallshire for suggesting that. - A new BLOSC_MIN_HEADER_LENGTH symbol in blosc.h tells how many bytes long is the minimum length of a Blosc header. `blosc_cbuffer_sizes()` only needs these bytes to be passed to work correctly. - Removed many warnings (related with potentially dangerous type-casting code) issued by MSVC 2008 in 64-bit mode. - Fixed a problem with the computation of the blocksize in the Blosc filter for HDF5. - Fixed a problem with large datatypes. See http://www.pytables.org/trac/ticket/288 for more info. - Now Blosc is able to work well even if you fork an existing process with a pool of threads. Bug discovered when PyTables runs in multiprocess environments. See http://pytables.org/trac/ticket/295 for details. - Added a new `blosc_getitem()` call to allow the retrieval of items in sizes smaller than the complete buffer. That is useful for the carray project, but certainly for others too. Changes from 0.9.5 to 1.0 ========================= - Added a filter for HDF5 so that people can use Blosc outside PyTables, if they want to. - Many small improvements, specially in README files. - Do not assume that size_t is uint_32 for every platform. - Added more protection for large buffers or in allocation memory routines. - The src/ directory has been renamed to blosc/. - The `maxbytes` parameter in `blosc_compress()` has been renamed to `destsize`. This is for consistency with the `blosc_decompress()` parameters. Changes from 0.9.4 to 0.9.5 =========================== - Now, compression level 0 is allowed, meaning not compression at all. The overhead of this mode will be always BLOSC_MAX_OVERHEAD (16) bytes. This mode actually represents using Blosc as a basic memory container. - Supported a new parameter `maxbytes` for ``blosc_compress()``. It represents a maximum of bytes for output. Tests unit added too. - Added 3 new functions for querying different metadata on compressed buffers. A test suite for testing the new API has been added too. Changes from 0.9.3 to 0.9.4 =========================== - Support for cross-platform big/little endian compatibility in Blosc headers has been added. - Fixed several failures exposed by the extremesuite. The problem was a bad check for limits in the buffer size while compressing. - Added a new suite in bench.c called ``debugsuite`` that is appropriate for debugging purposes. Now, the ``extremesuite`` can be used for running the complete (and extremely long) suite. Changes from 0.9.0 to 0.9.3 =========================== - Fixed several nasty bugs uncovered by the new suites in bench.c. Thanks to Tony Theodore and Gabriel Beckers for their (very) responsive beta testing and feedback. - Added several modes (suites), namely ``suite``, ``hardsuite`` and ``extremehardsuite`` in bench.c so as to allow different levels of testing. Changes from 0.8.0 to 0.9 ========================= - Internal format version bumped to 2 in order to allow an easy way to indicate that a buffer is being saved uncompressed. This is not supported yet, but it might be in the future. - Blosc can use threads now for leveraging the increasing number of multi-core processors out there. See README-threaded.txt for more info. - Added a protection for MacOSX so that it has to not link against posix_memalign() funtion, which seems not available in old versions of MacOSX (for example, Tiger). At nay rate, posix_memalign() is not necessary on Mac because 16 bytes alignment is ensured by default. Thanks to Ivan Vilata. Fixes #3.