util: drop write_content_size=True
This is now the default in python-zstandard 0.9. While we're here,
also add a comment about the ability to drop frame magic to save
space.
Differential Revision: https://phab.mercurial-scm.org/D3199
--- a/mercurial/util.py Mon Apr 09 10:13:29 2018 -0700
+++ b/mercurial/util.py Mon Apr 09 10:18:10 2018 -0700
@@ -3566,11 +3566,11 @@
class zstdrevlogcompressor(object):
def __init__(self, zstd, level=3):
- # Writing the content size adds a few bytes to the output. However,
- # it allows decompression to be more optimal since we can
- # pre-allocate a buffer to hold the result.
- self._cctx = zstd.ZstdCompressor(level=level,
- write_content_size=True)
+ # TODO consider omitting frame magic to save 4 bytes.
+ # This writes content sizes into the frame header. That is
+ # extra storage. But it allows a correct size memory allocation
+ # to hold the result.
+ self._cctx = zstd.ZstdCompressor(level=level)
self._dctx = zstd.ZstdDecompressor()
self._compinsize = zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE
self._decompinsize = zstd.DECOMPRESSION_RECOMMENDED_INPUT_SIZE