rust: speed up zstd decompression by re-using the decompression context
Admittedly, zstd is already pretty fast, but this change makes it
a bit faster yet: it saves ~5% of time it takes to read our large repo.
The actual motivating use case is treemanifest: in treemanifest
we end up reading *lots* of small directories, and many of them
need decompression, and there the saving for [rhg files] is >10%.
(which also seems unreasonable, we should probably keep things uncompressed more)
# scmutil.py - Mercurial core utility functions
#
# Copyright Olivia Mackall <olivia@selenic.com> and other
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from . import repoview
def cachetocopy(srcrepo):
"""return the list of cache file valuable to copy during a clone"""
# In local clones we're copying all nodes, not just served
# ones. Therefore copy all branch caches over.
cachefiles = [b'branch2']
cachefiles += [b'branch2-%s' % f for f in repoview.filtertable]
cachefiles += [b'rbc-names-v1', b'rbc-revs-v1']
cachefiles += [b'tags2']
cachefiles += [b'tags2-%s' % f for f in repoview.filtertable]
cachefiles += [b'hgtagsfnodes1']
return cachefiles