Changes 0.13.0:
* ``pytest-xdist`` ``pytest`` extension is now installed so tests can be
run in parallel.
* CI now builds ``manylinux2010`` and ``manylinux2014`` binary wheels
instead of a mix of ``manylinux2010`` and ``manylinux1``.
* Official support for Python 3.8 has been added.
* Bundled zstandard library upgraded from 1.4.3 to 1.4.4.
* Python code has been reformatted with black.
At least ZSTD_FRAMEHEADERSIZE_MIN and ZSTD_FRAMEHEADERSIZE_PREFIX
macros in 1.4.4 needs a `format' argument but py-zstandard is not
adapted to 1.4.4 yet.
PKGREVISION++
0.12.0:
Backwards Compatibility Notes
* Support for Python 3.4 has been dropped since Python 3.4 is no longer
a supported Python version upstream. (But it will likely continue to
work until Python 2.7 support is dropped and we port to Python 3.5+
APIs.)
Bug Fixes
* Fix ``ZstdDecompressor.__init__`` on 64-bit big-endian systems.
* Fix memory leak in ``ZstdDecompressionReader.seek()``.
Changes
* CI transitioned to Azure Pipelines (from AppVeyor and Travis CI).
* Switched to ``pytest`` for running tests (from ``nose``).
* Bundled zstandard library upgraded from 1.3.8 to 1.4.3.
0.11.0 (released 2019-02-24)
============================
Backwards Compatibility Nodes
-----------------------------
* ZstdDecompressor.read() now allows reading sizes of -1 or 0
and defaults to -1, per the documented behavior of
io.RawIOBase.read(). Previously, we required an argument that was
a positive value.
* The readline(), readlines(), __iter__, and __next__ methods
of ZstdDecompressionReader() now raise io.UnsupportedOperation
instead of NotImplementedError.
* ZstdDecompressor.stream_reader() now accepts a read_across_frames
argument. The default value will likely be changed in a future release
and consumers are advised to pass the argument to avoid unwanted change
of behavior in the future.
* setup.py now always disables the CFFI backend if the installed
CFFI package does not meet the minimum version requirements. Before, it was
possible for the CFFI backend to be generated and a run-time error to
occur.
* In the CFFI backend, CompressionReader and DecompressionReader
were renamed to ZstdCompressionReader and ZstdDecompressionReader,
respectively so naming is identical to the C extension. This should have
no meaningful end-user impact, as instances aren't meant to be
constructed directly.
* ZstdDecompressor.stream_writer() now accepts a write_return_read
argument to control whether write() returns the number of bytes
read from the source / written to the decompressor. It defaults to off,
which preserves the existing behavior of returning the number of bytes
emitted from the decompressor. The default will change in a future release
so behavior aligns with the specified behavior of io.RawIOBase.
* ZstdDecompressionWriter.__exit__ now calls self.close(). This
will result in that stream plus the underlying stream being closed as
well. If this behavior is not desirable, do not use instances as
context managers.
* ZstdCompressor.stream_writer() now accepts a write_return_read
argument to control whether write() returns the number of bytes read
from the source / written to the compressor. It defaults to off, which
preserves the existing behavior of returning the number of bytes emitted
from the compressor. The default will change in a future release so
behavior aligns with the specified behavior of io.RawIOBase.
* ZstdCompressionWriter.__exit__ now calls self.close(). This will
result in that stream plus any underlying stream being closed as well. If
this behavior is not desirable, do not use instances as context managers.
* ZstdDecompressionWriter no longer requires being used as a context
manager.
* ZstdCompressionWriter no longer requires being used as a context
manager.
* The overlap_size_log attribute on CompressionParameters instances
has been deprecated and will be removed in a future release. The
overlap_log attribute should be used instead.
* The overlap_size_log argument to CompressionParameters has been
deprecated and will be removed in a future release. The overlap_log
argument should be used instead.
* The ldm_hash_every_log attribute on CompressionParameters instances
has been deprecated and will be removed in a future release. The
ldm_hash_rate_log attribute should be used instead.
* The ldm_hash_every_log argument to CompressionParameters has been
deprecated and will be removed in a future release. The ldm_hash_rate_log
argument should be used instead.
* The compression_strategy argument to CompressionParameters has been
deprecated and will be removed in a future release. The strategy
argument should be used instead.
* The SEARCHLENGTH_MIN and SEARCHLENGTH_MAX constants are deprecated
and will be removed in a future release. Use MINMATCH_MIN and
MINMATCH_MAX instead.
* The zstd_cffi module has been renamed to zstandard.cffi. As had
been documented in the README file since the 0.9.0 release, the
module should not be imported directly at its new location. Instead,
import zstandard to cause an appropriate backend module to be loaded
automatically.
Bug Fixes
---------
* CFFI backend could encounter a failure when sending an empty chunk into
ZstdDecompressionObj.decompress(). The issue has been fixed.
* CFFI backend could encounter an error when calling
ZstdDecompressionReader.read() if there was data remaining in an
internal buffer. The issue has been fixed.
Changes
-------
* ZstDecompressionObj.decompress() now properly handles empty inputs in
the CFFI backend.
* ZstdCompressionReader now implements read1() and readinto1().
These are part of the io.BufferedIOBase interface.
* ZstdCompressionReader has gained a readinto(b) method for reading
compressed output into an existing buffer.
* ZstdCompressionReader.read() now defaults to size=-1 and accepts
read sizes of -1 and 0. The new behavior aligns with the documented
behavior of io.RawIOBase.
* ZstdCompressionReader now implements readall(). Previously, this
method raised NotImplementedError.
* ZstdDecompressionReader now implements read1() and readinto1().
These are part of the io.BufferedIOBase interface.
* ZstdDecompressionReader.read() now defaults to size=-1 and accepts
read sizes of -1 and 0. The new behavior aligns with the documented
behavior of io.RawIOBase.
* ZstdDecompressionReader() now implements readall(). Previously, this
method raised NotImplementedError.
* The readline(), readlines(), __iter__, and __next__ methods
of ZstdDecompressionReader() now raise io.UnsupportedOperation
instead of NotImplementedError. This reflects a decision to never
implement text-based I/O on (de)compressors and keep the low-level API
operating in the binary domain.
* README.rst now documented how to achieve linewise iteration using
an io.TextIOWrapper with a ZstdDecompressionReader.
* ZstdDecompressionReader has gained a readinto(b) method for
reading decompressed output into an existing buffer. This allows chaining
to an io.TextIOWrapper on Python 3 without using an io.BufferedReader.
* ZstdDecompressor.stream_reader() now accepts a read_across_frames
argument to control behavior when the input data has multiple zstd
*frames*. When False (the default for backwards compatibility), a
read() will stop when the end of a zstd *frame* is encountered. When
True, read() can potentially return data spanning multiple zstd
*frames*. The default will likely be changed to True in a future
release.
* setup.py now performs CFFI version sniffing and disables the CFFI
backend if CFFI is too old. Previously, we only used install_requires
to enforce the CFFI version and not all build modes would properly enforce
the minimum CFFI version.
* CFFI's ZstdDecompressionReader.read() now properly handles data
remaining in any internal buffer. Before, repeated read() could
result in *random* errors.
* Upgraded various Python packages in CI environment.
* Upgrade to hypothesis 4.5.11.
* In the CFFI backend, CompressionReader and DecompressionReader
were renamed to ZstdCompressionReader and ZstdDecompressionReader,
respectively.
* ZstdDecompressor.stream_writer() now accepts a write_return_read
argument to control whether write() returns the number of bytes read
from the source. It defaults to False to preserve backwards
compatibility.
* ZstdDecompressor.stream_writer() now implements the io.RawIOBase
interface and behaves as a proper stream object.
* ZstdCompressor.stream_writer() now accepts a write_return_read
argument to control whether write() returns the number of bytes read
from the source. It defaults to False to preserve backwards
compatibility.
* ZstdCompressionWriter now implements the io.RawIOBase interface and
behaves as a proper stream object. close() will now close the stream
and the underlying stream (if possible). __exit__ will now call
close(). Methods like writable() and fileno() are implemented.
* ZstdDecompressionWriter no longer must be used as a context manager.
* ZstdCompressionWriter no longer must be used as a context manager.
When not using as a context manager, it is important to call
flush(FRAME_FRAME) or the compression stream won't be properly
terminated and decoders may complain about malformed input.
* ZstdCompressionWriter.flush() (what is returned from
ZstdCompressor.stream_writer()) now accepts an argument controlling the
flush behavior. Its value can be one of the new constants
FLUSH_BLOCK or FLUSH_FRAME.
* ZstdDecompressionObj instances now have a flush([length=None]) method.
This provides parity with standard library equivalent types.
* CompressionParameters no longer redundantly store individual compression
parameters on each instance. Instead, compression parameters are stored inside
the underlying ZSTD_CCtx_params instance. Attributes for obtaining
parameters are now properties rather than instance variables.
* Exposed the STRATEGY_BTULTRA2 constant.
* CompressionParameters instances now expose an overlap_log attribute.
This behaves identically to the overlap_size_log attribute.
* CompressionParameters() now accepts an overlap_log argument that
behaves identically to the overlap_size_log argument. An error will be
raised if both arguments are specified.
* CompressionParameters instances now expose an ldm_hash_rate_log
attribute. This behaves identically to the ldm_hash_every_log attribute.
* CompressionParameters() now accepts a ldm_hash_rate_log argument that
behaves identically to the ldm_hash_every_log argument. An error will be
raised if both arguments are specified.
* CompressionParameters() now accepts a strategy argument that behaves
identically to the compression_strategy argument. An error will be raised
if both arguments are specified.
* The MINMATCH_MIN and MINMATCH_MAX constants were added. They are
semantically equivalent to the old SEARCHLENGTH_MIN and
SEARCHLENGTH_MAX constants.
* Bundled zstandard library upgraded from 1.3.7 to 1.3.8.
* setup.py denotes support for Python 3.7 (Python 3.7 was supported and
tested in the 0.10 release).
* zstd_cffi module has been renamed to zstandard.cffi.
* ZstdCompressor.stream_writer() now reuses a buffer in order to avoid
allocating a new buffer for every operation. This should result in faster
performance in cases where write() or flush() are being called
frequently.
* Bundled zstandard library upgraded from 1.3.6 to 1.3.7.
0.10.1:
Backwards Compatibility Notes
* ZstdCompressor.stream_reader().closed is now a property instead of a
method.
* ZstdDecompressor.stream_reader().closed is now a property instead of a
method.
Changes
* Stop attempting to package Python 3.6 for Miniconda. The latest version of
Miniconda is using Python 3.7. The Python 3.6 Miniconda packages were a lie
since this were built against Python 3.7.
* ZstdCompressor.stream_reader()'s and ZstdDecompressor.stream_reader()'s
closed attribute is now a read-only property instead of a method. This now
properly matches the IOBase API and allows instances to be used in more
places that accept IOBase instances.
0.10.0:
Backwards Compatibility Notes
* ZstdDecompressor.stream_reader().read() now consistently requires an
argument in both the C and CFFI backends. Before, the CFFI implementation
would assume a default value of -1, which was later rejected.
* The compress_literals argument and attribute has been removed from
zstd.ZstdCompressionParameters because it was removed by the zstd 1.3.5
API.
* ZSTD_CCtx_setParametersUsingCCtxParams() is no longer called on every
operation performed against ZstdCompressor instances. The reason for this
change is that the zstd 1.3.5 API no longer allows this without calling
ZSTD_CCtx_resetParameters() first. But if we called
ZSTD_CCtx_resetParameters() on every operation, we'd have to redo
potentially expensive setup when using dictionaries. We now call
ZSTD_CCtx_reset() on every operation and don't attempt to change
compression parameters.
* Objects returned by ZstdCompressor.stream_reader() no longer need to be
used as a context manager. The context manager interface still exists and its
behavior is unchanged.
* Objects returned by ZstdDecompressor.stream_reader() no longer need to be
used as a context manager. The context manager interface still exists and its
behavior is unchanged.
Bug Fixes
* ZstdDecompressor.decompressobj().decompress() should now return all data
from internal buffers in more scenarios. Before, it was possible for data to
remain in internal buffers. This data would be emitted on a subsequent call
to decompress(). The overall output stream would still be valid. But if
callers were expecting input data to exactly map to output data (say the
producer had used flush(COMPRESSOBJ_FLUSH_BLOCK) and was attempting to
map input chunks to output chunks), then the previous behavior would be
wrong. The new behavior is such that output from
flush(COMPRESSOBJ_FLUSH_BLOCK) fed into decompressobj().decompress()
should produce all available compressed input.
* ZstdDecompressor.stream_reader().read() should no longer segfault after
a previous context manager resulted in error.
* ZstdCompressor.compressobj().flush(COMPRESSOBJ_FLUSH_BLOCK) now returns
all data necessary to flush a block. Before, it was possible for the
flush() to not emit all data necessary to fully represent a block. This
would mean decompressors wouldn't be able to decompress all data that had been
fed into the compressor and flush()ed.
New Features
* New module constants BLOCKSIZELOG_MAX, BLOCKSIZE_MAX,
TARGETLENGTH_MAX that expose constants from libzstd.
* New ZstdCompressor.chunker() API for manually feeding data into a
compressor and emitting chunks of a fixed size. Like compressobj(), the
API doesn't impose restrictions on the input or output types for the
data streams. Unlike compressobj(), it ensures output chunks are of a
fixed size. This makes this API useful when the compressed output is being
fed into an I/O layer, where uniform write sizes are useful.
* ZstdCompressor.stream_reader() no longer needs to be used as a context
manager.
* ZstdDecompressor.stream_reader() no longer needs to be used as a context
manager.
* Bundled zstandard library upgraded from 1.3.4 to 1.3.6.
Changes
* Added zstd_cffi.py and NEWS.rst to MANIFEST.in.
* zstandard.__version__ is now defined.
* Upgrade pip, setuptools, wheel, and cibuildwheel packages to latest versions.
* Upgrade various packages used in CI to latest versions. Notably tox (in
order to support Python 3.7).
* Use relative paths in setup.py to appease Python 3.7.
* Added CI for Python 3.7.
0.9.0:
Backwards Compatibility Notes
CFFI 1.11 or newer is now required (previous requirement was 1.8).
The primary module is now zstandard. Please change imports of zstd and zstd_cffi to import zstandard. See the README for more. Support for importing the old names will be dropped in the next release.
ZstdCompressor.read_from() and ZstdDecompressor.read_from() have been renamed to read_to_iter(). read_from() is aliased to the new name and will be deleted in a future release.
Support for Python 2.6 has been removed.
Support for Python 3.3 has been removed.
The selectivity argument to train_dictionary() has been removed, as the feature disappeared from zstd 1.3.
Support for legacy dictionaries has been removed. Cover dictionaries are now the default. train_cover_dictionary() has effectively been renamed to train_dictionary().
The allow_empty argument from ZstdCompressor.compress() has been deleted and the method now allows empty inputs to be compressed by default.
estimate_compression_context_size() has been removed. Use CompressionParameters.estimated_compression_context_size() instead.
get_compression_parameters() has been removed. Use CompressionParameters.from_level() instead.
The arguments to CompressionParameters.__init__() have changed. If you were using positional arguments before, the positions now map to different arguments. It is recommended to use keyword arguments to construct CompressionParameters instances.
TARGETLENGTH_MAX constant has been removed (it disappeared from zstandard 1.3.4).
ZstdCompressor.write_to() and ZstdDecompressor.write_to() have been renamed to ZstdCompressor.stream_writer() and ZstdDecompressor.stream_writer(), respectively. The old names are still aliased, but will be removed in the next major release.
Content sizes are written into frame headers by default (ZstdCompressor(write_content_size=True) is now the default).
CompressionParameters has been renamed to ZstdCompressionParameters for consistency with other types. The old name is an alias and will be removed in the next major release.
Bug Fixes
Fixed memory leak in ZstdCompressor.copy_stream().
Fixed memory leak in ZstdDecompressor.copy_stream().
Fixed memory leak of ZSTD_DDict instances in CFFI's ZstdDecompressor.
New Features
Bundlded zstandard library upgraded from 1.1.3 to 1.3.4. This delivers various bug fixes and performance improvements. It also gives us access to newer features.
Support for negative compression levels.
Support for long distance matching (facilitates compression ratios that approach LZMA).
Supporting for reading empty zstandard frames (with an embedded content size of 0).
Support for writing and partial support for reading zstandard frames without a magic header.
New stream_reader() API that exposes the io.RawIOBase interface (allows you to .read() from a file-like object).
Several minor features, bug fixes, and performance enhancements.
Wheels for Linux and macOS are now provided with releases.
Changes
Functions accepting bytes data now use the buffer protocol and can accept more types (like memoryview and bytearray).
Add #includes so compilation on OS X and BSDs works.
New ZstdDecompressor.stream_reader() API to obtain a read-only i/o stream of decompressed data for a source.
New ZstdCompressor.stream_reader() API to obtain a read-only i/o stream of compressed data for a source.
Renamed ZstdDecompressor.read_from() to ZstdDecompressor.read_to_iter(). The old name is still available.
Renamed ZstdCompressor.read_from() to ZstdCompressor.read_to_iter(). read_from() is still available at its old location.
Introduce the zstandard module to import and re-export the C or CFFI backend as appropriate. Behavior can be controlled via the PYTHON_ZSTANDARD_IMPORT_POLICY environment variable. See README for usage info.
Vendored version of zstd upgraded to 1.3.4.
Added module constants CONTENTSIZE_UNKNOWN and CONTENTSIZE_ERROR.
Add STRATEGY_BTULTRA compression strategy constant.
Switch from deprecated ZSTD_getDecompressedSize() to ZSTD_getFrameContentSize() replacement.
ZstdCompressor.compress() can now compress empty inputs without requiring special handling.
ZstdCompressor and ZstdDecompressor now have a memory_size() method for determining the current memory utilization of the underlying zstd primitive.
train_dictionary() has new arguments and functionality for trying multiple variations of COVER parameters and selecting the best one.
Added module constants LDM_MINMATCH_MIN, LDM_MINMATCH_MAX, and LDM_BUCKETSIZELOG_MAX.
Converted all consumers to the zstandard new advanced API, which uses ZSTD_compress_generic()
CompressionParameters.__init__ now accepts several more arguments, including support for long distance matching.
ZstdCompressionDict.__init__ now accepts a dict_type argument that controls how the dictionary should be interpreted. This can be used to force the use of content-only dictionaries or to require the presence of the dictionary magic header.
ZstdCompressionDict.precompute_compress() can be used to precompute the compression dictionary so it can efficiently be used with multiple ZstdCompressor instances.
Digested dictionaries are now stored in ZstdCompressionDict instances, created automatically on first use, and automatically reused by all ZstdDecompressor instances bound to that dictionary.
All meaningful functions now accept keyword arguments.
ZstdDecompressor.decompressobj() now accepts a write_size argument to control how much work to perform on every decompressor invocation.
ZstdCompressor.write_to() now exposes a tell(), which exposes the total number of bytes written so far.
ZstdDecompressor.stream_reader() now supports seek() when moving forward in the stream.
Removed TARGETLENGTH_MAX constant.
Added frame_header_size(data) function.
Added frame_content_size(data) function.
Consumers of ZSTD_decompress* have been switched to the new advanced decompression API.
ZstdCompressor and ZstdCompressionParams can now be constructed with negative compression levels.
ZstdDecompressor now accepts a max_window_size argument to limit the amount of memory required for decompression operations.
FORMAT_ZSTD1 and FORMAT_ZSTD1_MAGICLESS constants to be used with the format compression parameter to control whether the frame magic header is written.
ZstdDecompressor now accepts a format argument to control the expected frame format.
ZstdCompressor now has a frame_progression() method to return information about the current compression operation.
Error messages in CFFI no longer have b'' literals.
Compiler warnings and underlying overflow issues on 32-bit platforms have been fixed.
Builds in CI now build with compiler warnings as errors. This should hopefully fix new compiler warnings from being introduced.
Make ZstdCompressor(write_content_size=True) and CompressionParameters(write_content_size=True) the default.
CompressionParameters has been renamed to ZstdCompressionParameters.
0.8.1:
Add #includes so compilation on OS X and BSDs works.
0.8.0:
CompressionParameters now has a estimated_compression_context_size() method. zstd.estimate_compression_context_size() is now deprecated and slated for removal.
Implemented a lot of fuzzing tests.
CompressionParameters instances now perform extra validation by calling ZSTD_checkCParams() at construction time.
multi_compress_to_buffer() API for compressing multiple inputs as a single operation, as efficiently as possible.
ZSTD_CStream instances are now used across multiple operations on ZstdCompressor instances, resulting in much better performance for APIs that do streaming.
ZSTD_DStream instances are now used across multiple operations on ZstdDecompressor instances, resulting in much better performance for APIs that do streaming.
train_dictionary() now releases the GIL.
Support for training dictionaries using the COVER algorithm.
multi_decompress_to_buffer() API for decompressing multiple frames as a single operation, as efficiently as possible.
Support for multi-threaded compression.
Disable deprecation warnings when compiling CFFI module.
Fixed memory leak in train_dictionary().
Removed DictParameters type.
train_dictionary() now accepts keyword arguments instead of a DictParameters instance to control dictionary generation.
Temporarily remove the zstd buildlink as py-zstandard includes
its own version that it wants to use. Future versions will
support using a system supplied zstd but this one doesn't yet.
Also prevent setup.py from picking up cffi by accident so the
PLIST is stable.
This project provides Python bindings for interfacing with the
Zstandard compression library. A C extension and CFFI interface are
provided.
The primary goal of the project is to provide a rich interface to
the underlying C API through a Pythonic interface while not sacrificing
performance. This means exposing most of the features and flexibility
of the C API while not sacrificing usability or safety that Python
provides.
