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  • Committer: Robert Collins
  • Date: 2010-05-05 00:05:29 UTC
  • mto: This revision was merged to the branch mainline in revision 5206.
  • Revision ID: robertc@robertcollins.net-20100505000529-ltmllyms5watqj5u
Make 'pydoc bzrlib.tests.build_tree_shape' useful.

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bzrlib/chunk_writer.py
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"""ChunkWriter: write compressed data out with a fixed upper bound."""
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from __future__ import absolute_import
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import zlib
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from zlib import Z_FINISH, Z_SYNC_FLUSH
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        :param chunk_size: The total byte count to emit at the end of the
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            chunk.
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        :param reserved: How many bytes to allow for reserved data. reserved
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            data space can only be written to via the write(...,
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            reserved=True).
 
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            data space can only be written to via the write(..., reserved=True).
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        """
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        self.chunk_size = chunk_size
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        self.compressor = zlib.compressobj()
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        bytes that did not fit in the chunk.
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        :return: (compressed_bytes, unused_bytes, num_nulls_needed)
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            * compressed_bytes: a list of bytes that were output from the
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              compressor. If the compressed length was not exactly chunk_size,
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              the final string will be a string of all null bytes to pad this
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              to chunk_size
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            * unused_bytes: None, or the last bytes that were added, which we
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              could not fit.
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            * num_nulls_needed: How many nulls are padded at the end
 
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            compressed_bytes    a list of bytes that were output from the
 
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                                compressor. If the compressed length was not
 
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                                exactly chunk_size, the final string will be a
 
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                                string of all null bytes to pad this to
 
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                                chunk_size
 
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            unused_bytes        None, or the last bytes that were added, which
 
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                                we could not fit.
 
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            num_nulls_needed    How many nulls are padded at the end
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        """
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        self.bytes_in = None  # Free the data cached so far, we don't need it
 
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        self.bytes_in = None # Free the data cached so far, we don't need it
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        out = self.compressor.flush(Z_FINISH)
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        self.bytes_list.append(out)
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        self.bytes_out_len += len(out)
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                                 % (self.bytes_out_len, self.chunk_size))
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        nulls_needed = self.chunk_size - self.bytes_out_len
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        if nulls_needed:
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            self.bytes_list.append(b"\x00" * nulls_needed)
 
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            self.bytes_list.append("\x00" * nulls_needed)
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        return self.bytes_list, self.unused_bytes, nulls_needed
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    def set_optimize(self, for_size=True):
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        :param extra_bytes: Optional, if supplied we will add it with
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            Z_SYNC_FLUSH
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        :return: (bytes_out, bytes_out_len, alt_compressed)
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            * bytes_out: is the compressed bytes returned from the compressor
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            * bytes_out_len: the length of the compressed output
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            * compressor: An object with everything packed in so far, and
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              Z_SYNC_FLUSH called.
 
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            bytes_out   is the compressed bytes returned from the compressor
 
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            bytes_out_len the length of the compressed output
 
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            compressor  An object with everything packed in so far, and
 
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                        Z_SYNC_FLUSH called.
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        """
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        compressor = zlib.compressobj()
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        bytes_out = []
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                    self.bytes_list = bytes_out
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                    self.bytes_out_len = this_len
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        return False
 
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