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bdiff: improve worst case behavior by 100x....
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.

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packagescan.py
125 lines | 4.3 KiB | text/x-python | PythonLexer
# packagescan.py - Helper module for identifing used modules.
# Used for the py2exe distutil.
# This module must be the first mercurial module imported in setup.py
#
# Copyright 2005 Volker Kleinfeld <Volker.Kleinfeld@gmx.de>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
import glob
import os
import sys
import ihooks
import types
import string
# Install this module as fake demandload module
sys.modules['mercurial.demandload'] = sys.modules[__name__]
# Requiredmodules contains the modules imported by demandload.
# Please note that demandload can be invoked before the
# mercurial.packagescan.scan method is invoked in case a mercurial
# module is imported.
requiredmodules = {}
def demandload(scope, modules):
""" fake demandload function that collects the required modules
foo import foo
foo bar import foo, bar
foo.bar import foo.bar
foo:bar from foo import bar
foo:bar,quux from foo import bar, quux
foo.bar:quux from foo.bar import quux"""
for m in modules.split():
mod = None
try:
module, fromlist = m.split(':')
fromlist = fromlist.split(',')
except:
module = m
fromlist = []
mod = __import__(module, scope, scope, fromlist)
if fromlist == []:
# mod is only the top package, but we need all packages
comp = module.split('.')
i = 1
mn = comp[0]
while True:
# mn and mod.__name__ might not be the same
scope[mn] = mod
requiredmodules[mod.__name__] = 1
if len(comp) == i: break
mod = getattr(mod,comp[i])
mn = string.join(comp[:i+1],'.')
i += 1
else:
# mod is the last package in the component list
requiredmodules[mod.__name__] = 1
for f in fromlist:
scope[f] = getattr(mod,f)
if type(scope[f]) == types.ModuleType:
requiredmodules[scope[f].__name__] = 1
class SkipPackage(Exception):
def __init__(self, reason):
self.reason = reason
scan_in_progress = False
def scan(libpath,packagename):
""" helper for finding all required modules of package <packagename> """
global scan_in_progress
scan_in_progress = True
# Use the package in the build directory
libpath = os.path.abspath(libpath)
sys.path.insert(0,libpath)
packdir = os.path.join(libpath,packagename.replace('.', '/'))
# A normal import would not find the package in
# the build directory. ihook is used to force the import.
# After the package is imported the import scope for
# the following imports is settled.
p = importfrom(packdir)
globals()[packagename] = p
sys.modules[packagename] = p
# Fetch the python modules in the package
cwd = os.getcwd()
os.chdir(packdir)
pymodulefiles = glob.glob('*.py')
extmodulefiles = glob.glob('*.pyd')
os.chdir(cwd)
# Import all python modules and by that run the fake demandload
for m in pymodulefiles:
if m == '__init__.py': continue
tmp = {}
mname,ext = os.path.splitext(m)
fullname = packagename+'.'+mname
try:
__import__(fullname,tmp,tmp)
except SkipPackage, inst:
print >> sys.stderr, 'skipping %s: %s' % (fullname, inst.reason)
continue
requiredmodules[fullname] = 1
# Import all extension modules and by that run the fake demandload
for m in extmodulefiles:
tmp = {}
mname,ext = os.path.splitext(m)
fullname = packagename+'.'+mname
__import__(fullname,tmp,tmp)
requiredmodules[fullname] = 1
def getmodules():
return requiredmodules.keys()
def importfrom(filename):
"""
import module/package from a named file and returns the module.
It does not check on sys.modules or includes the module in the scope.
"""
loader = ihooks.BasicModuleLoader()
path, file = os.path.split(filename)
name, ext = os.path.splitext(file)
m = loader.find_module_in_dir(name, path)
if not m:
raise ImportError, name
m = loader.load_module(name, m)
return m