view tests/test-demandimport.py @ 17962:4c29668ca316 stable

util: make chunkbuffer non-quadratic on Windows

The old str-based += collector performed very nicely on Linux, but
turns out to be quadratically expensive on Windows, causing
chunkbuffer to dominate in profiles.

This list-based version has been measured to significantly improve
performance with large chunks on Windows, with negligible overall
overhead on Linux (though microbenchmarks show it to be about 50% slower).

This may increase memory overhead where += didn't behave quadratically. If we
want to gather up 1G of data to join, we temporarily have 1G in our
list and 1G in our string.

from mercurial import demandimport
demandimport.enable()

import re

rsub = re.sub
def f(obj):
    l = repr(obj)
    l = rsub("0x[0-9a-fA-F]+", "0x?", l)
    l = rsub("from '.*'", "from '?'", l)
    l = rsub("'<[a-z]*>'", "'<whatever>'", l)
    return l

import os

print "os =", f(os)
print "os.system =", f(os.system)
print "os =", f(os)

from mercurial import util

print "util =", f(util)
print "util.system =", f(util.system)
print "util =", f(util)
print "util.system =", f(util.system)

import re as fred
print "fred =", f(fred)

import sys as re
print "re =", f(re)

print "fred =", f(fred)
print "fred.sub =", f(fred.sub)
print "fred =", f(fred)

print "re =", f(re)
print "re.stderr =", f(re.stderr)
print "re =", f(re)