0.13.0

Changes

• 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.

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 (#91).
• Fix memory leak in ZstdDecompressionReader.seek() (#82).

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

New Features

• zstd library upgraded from 1.3.6 to 1.3.8.
• ZstdCompressor.stream_reader(), ZstdCompressor.stream_writer(), ZstdDecompressor.stream_reader(), and ZstdDecompressor.stream_writer() should now completely implement the io.RawIOBase interface, allowing them to be used as fully-featured streams. One can combine an instance with say an io.TextIOWrapper, codecs.StreamReader, or codecs.StreamWriter to transparently convert between binary and textual data or apply encodings to data. A stream reader or writer should interoperate with any Python code that accepts a stream-like object. Please note that some implementation details may change slightly in the future in order to ensure better compatibility with the stream interfaces.
• ZstdDecompressor.stream_reader() can now read inputs that have multiple zstd frames. Look for future releases to improve support for reading sources with multiple frames.

Backwards Compatibility Notes

• 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 (#57).
• ZstdCompressionWriter no longer requires being used as a context
  manager (#57).
• 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. (#71)

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. (#13)
• 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. (#69)
• CFFI's ZstdDecompressionReader.read() now properly handles data
  remaining in any internal buffer. Before, repeated read() could
  result in random errors. (#71)
• 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
  flu...

0.10.2

Bug Fixes

• zstd_cffi.py added to setup.py (#60).

Changes

• Change some integer casts to avoid ssize_t (#61).

0.10.1

Backwards Compatibility Notes

• ZstdCompressor.stream_reader().closed is now a property instead of a
  method (#58).
• ZstdDecompressor.stream_reader().closed is now a property instead of a
  method (#58).

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 (#56).
• 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. (#55).

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 (#34).
• ZstdDecompressor.stream_reader() no longer needs to be used as a context
  manager (#34).
• Bundled zstandard library upgraded from 1.3.4 to 1.3.6.

Changes

• zstandard.__version__ is now defined (#50).
• 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 (#51).
• Added CI for Python 3.7.

0.9.1

This release contains packaging improvements. No changes to the Python library code were made in this release.

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() (#40) (from 0.8.2).
• Fixed memory leak in ZstdDecompressor.copy_stream() (#35) (from 0.8.2).
• 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) (#26).
• Add #includes so compilation on OS X and BSDs works (#20).
• 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.

0.8.2

• Fixed memory leak in ZstdCompressor.copy_stream() (#40).
• Fixed memory leak in ZstdDecompressor.copy_stream() (#35).

0.8.1

• Add #includes so compilation on OS X and BSDs works (#20).