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.
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