| Author: | Francesc Alted |
|---|---|
| Contact: | [email protected] |
| URL: | http://www.blosc.org |
#XXX version-specific blurb XXX#
- 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.
- 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.
- 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.
Using blosc_compress_ctx() / blosc_decompress_ctx() inside the HDF5 compressor for allowing operation in multiprocess scenarios. See: PyTables/PyTables#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.
- 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.
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.
- Fixed a bug in blosc_getitem() introduced in 1.4.0. Added a test for blosc_getitem() as well.
- 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.
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
- Removed a pointer from 'pointer from integer without a cast' compiler warning due to a bad macro definition.
- 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.
- 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.
- 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).
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 PyTables/PyTables#21.
Thanks to Antonio Valentino for the fix!
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);
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!
- 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
- Fixed a problem with global lock not being initialized. This affected mostly to Windows platforms. Thanks to Christoph Gohlke for finding the cure!
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.
- Fix compile error with msvc compilers (Christoph Gohlke)
- 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 -1in 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).
- Much improved compression ratio when using large blocks (> 64 KB) and high compression levels (> 6) under some circumstances (special data distribution). Closes #7.
- Fixes for small typesizes (#6 and #1 of python-blosc).
- 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).
- 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.
- 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.
- 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.
- 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
debugsuitethat is appropriate for debugging purposes. Now, theextremesuitecan be used for running the complete (and extremely long) suite.
- 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,hardsuiteandextremehardsuitein bench.c so as to allow different levels of testing.
- 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.