view tests/test-parseindex @ 2577:fa76c5d609c9

bdiff: improve worst case behavior by 100x. on 5.8MB (244.000 lines) text file with similar lines, hash before this change made diff against empty file take 75 seconds. this change improves performance to 0.6 seconds. result is that clone of smallish repo (137MB) with some files like this takes 1 minute instead of 10 minutes. common case of diff is 10% slower now, probably because of worse cache locality. but diff does not affect overall performance in common case (less than 1% of runtime is in diff when it is working ok), so this tradeoff looks good.
author Vadim Gelfer <vadim.gelfer@gmail.com>
date Fri, 07 Jul 2006 15:02:55 -0700
parents 6563438219e3
children c0b449154a90
line wrap: on
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#!/bin/sh
#
# 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' -d '1000000 0'

echo >> foo
hg commit -m 'change foo' -d '1000001 0'
hg log -r 0:

cat >> test.py << EOF
from mercurial import changelog, util
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 = util.opener(*args)
    def wrapper(*a):
        f = o(*a)
        return singlebyteread(f)
    return wrapper

cl = changelog.changelog(opener('.hg'))
print cl.count(), 'revisions:'
for r in xrange(cl.count()):
    print short(cl.node(r))
EOF

python test.py