3200 class _zstdengine(compressionengine):

  3201     def name(self):

  3202         return 'zstd'

  3203 

  3204     @propertycache

  3205     def _module(self):

  3206         # Not all installs have the zstd module available. So defer importing

  3207         # until first access.

  3208         try:

  3209             from . import zstd

  3210             # Force delayed import.

  3211             zstd.__version__

  3212             return zstd

  3213         except ImportError:

  3214             return None

  3215 

  3216     def available(self):

  3217         return bool(self._module)

  3218 

  3219     def bundletype(self):

  3220         return 'zstd', 'ZS'

  3221 

  3222     def compressstream(self, it, opts=None):

  3223         opts = opts or {}

  3224         # zstd level 3 is almost always significantly faster than zlib

  3225         # while providing no worse compression. It strikes a good balance

  3226         # between speed and compression.

  3227         level = opts.get('level', 3)

  3228 

  3229         zstd = self._module

  3230         z = zstd.ZstdCompressor(level=level).compressobj()

  3231         for chunk in it:

  3232             data = z.compress(chunk)

  3233             if data:

  3234                 yield data

  3235 

  3236         yield z.flush()

  3237 

  3238     def decompressorreader(self, fh):

  3239         zstd = self._module

  3240         dctx = zstd.ZstdDecompressor()

  3241         return chunkbuffer(dctx.read_from(fh))

  3242 

  3243 compengines.register(_zstdengine())

  3244