Mercurial > hg
view tests/test-parseindex.t @ 16414:e8d37b78acfb
parsers: use base-16 trie for faster node->rev mapping
This greatly speeds up node->rev lookups, with results that are
often user-perceptible: for instance, "hg --time log" of the node
associated with rev 1000 on a linux-2.6 repo improves from 0.3
seconds to 0.03. I have not found any instances of slowdowns.
The new perfnodelookup command in contrib/perf.py demonstrates the
speedup more dramatically, since it performs no I/O. For a single
lookup, the new code is about 40x faster.
These changes also prepare the ground for the possibility of further
improving the performance of prefix-based node lookups.
author | Bryan O'Sullivan <bryano@fb.com> |
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date | Thu, 12 Apr 2012 14:05:59 -0700 |
parents | d13913355390 |
children | f2719b387380 |
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revlog.parseindex must be able to parse the index file even if an index entry is split between two 64k blocks. The ideal test would be to create an index file with inline data where 64k < size < 64k + 64 (64k is the size of the read buffer, 64 is the size of an index entry) and with an index entry starting right before the 64k block boundary, and try to read it. We approximate that by reducing the read buffer to 1 byte. $ hg init a $ cd a $ echo abc > foo $ hg add foo $ hg commit -m 'add foo' $ echo >> foo $ hg commit -m 'change foo' $ hg log -r 0: changeset: 0:7c31755bf9b5 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: add foo changeset: 1:26333235a41c tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: change foo $ cat >> test.py << EOF > from mercurial import changelog, scmutil > from mercurial.node import * > > class singlebyteread(object): > def __init__(self, real): > self.real = real > > def read(self, size=-1): > if size == 65536: > size = 1 > return self.real.read(size) > > def __getattr__(self, key): > return getattr(self.real, key) > > def opener(*args): > o = scmutil.opener(*args) > def wrapper(*a): > f = o(*a) > return singlebyteread(f) > return wrapper > > cl = changelog.changelog(opener('.hg/store')) > print len(cl), 'revisions:' > for r in cl: > print short(cl.node(r)) > EOF $ python test.py 2 revisions: 7c31755bf9b5 26333235a41c