view mercurial/strutil.py @ 5339:058e93c3d07d

I have spotted the biggest bottleneck in "bdiff.c". Actually it was
pretty easy to find after I recompiled the python interpreter and
mercurial for profiling.

In "bdiff.c" function "equatelines" allocates the minimum hash table
size, which can lead to tons of collisions. I introduced an
"overcommit" factor of 16, this is, I allocate 16 times more memory
than the minimum value. Overcommiting 128 times does not improve the
performance over the 16-times case.

# strutil.py - string utilities for Mercurial
#
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

def findall(haystack, needle, start=0, end=None):
    if end is None:
        end = len(haystack)
    if end < 0:
        end += len(haystack)
    if start < 0:
        start += len(haystack)
    while start < end:
        c = haystack.find(needle, start, end)
        if c == -1:
            break
        yield c
        start = c + 1

def rfindall(haystack, needle, start=0, end=None):
    if end is None:
        end = len(haystack)
    if end < 0:
        end += len(haystack)
    if start < 0:
        start += len(haystack)
    while end >= 0:
        c = haystack.rfind(needle, start, end)
        if c == -1:
            break
        yield c
        end = c - 1