Part of bzrlib.chunk_writer View In Hierarchy
ChunkWriter allows writing of compressed data with a fixed size.
If less data is supplied than fills a chunk, the chunk is padded with NULL bytes. If more data is supplied, then the writer packs as much in as it can, but never splits any item it was given.
|Class Variables||_max_repack||To fit the maximum number of entries into a node, we will sometimes start over and compress the whole list to get tighter packing. We get diminishing returns after a while, so this limits the number of times we will try. The default is to try to avoid recompressing entirely, but setting this to something like 20 will give maximum compression.|
|_max_zsync||Another tunable nob. If _max_repack is set to 0, then you can limit the number of times we will try to pack more data into a node. This allows us to do a single compression pass, rather than trying until we overflow, and then recompressing again.|
|Method||__init__||Create a ChunkWriter to write chunk_size chunks.|
|Method||finish||Finish the chunk.|
|Method||set_optimize||Change how we optimize our writes.|
|Method||write||Write some bytes to the chunk.|
|Method||_recompress_all_bytes_in||Recompress the current bytes_in, and optionally more.|
|Parameters||chunk_size||The total byte count to emit at the end of the chunk.|
|reserved||How many bytes to allow for reserved data. reserved data space can only be written to via the write(..., reserved=True).|
This returns the final compressed chunk, and either None, or the bytes that did not fit in the chunk.
(compressed_bytes, unused_bytes, num_nulls_needed)
|Parameters||for_size||If True, optimize for minimum space usage, otherwise optimize for fastest writing speed.|
|Parameters||extra_bytes||Optional, if supplied we will add it with Z_SYNC_FLUSH|
(bytes_out, bytes_out_len, alt_compressed)