zstandard 0.10.0

on Python PyPI

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.