Mercurial > hg
view contrib/simplemerge @ 30418:1156ec81f709
util: improve iterfile so it chooses code path wisely
We have performance concerns on "iterfile" as it is 4X slower on normal
files. While modern systems have the nice property that reading a "fast"
(on-disk) file cannot be interrupted and should be made use of.
This patch dumps the related knowledge in comments. And "iterfile" chooses
code paths wisely:
1. If it's CPython 3, or PyPY, use the fast path.
2. If fp is a normal file, use the fast path.
3. If fp is not a normal file and CPython version >= 2.7.4, use the same
workaround (4x slower) as before.
4. If fp is not a normal file and CPython version < 2.7.4, use another
workaround (2x slower but may block longer then necessary) which
basically re-invents the buffer + readline logic in Python.
This will give us good confidence on both correctness and performance
dealing with EINTR in iterfile(fp) for all known supported Python versions.
author | Jun Wu <quark@fb.com> |
---|---|
date | Tue, 15 Nov 2016 20:25:51 +0000 |
parents | 863075fd4cd0 |
children | d83ca854fa21 |
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#!/usr/bin/env python from mercurial import demandimport demandimport.enable() import sys from mercurial.i18n import _ from mercurial import error, simplemerge, fancyopts, util, ui options = [('L', 'label', [], _('labels to use on conflict markers')), ('a', 'text', None, _('treat all files as text')), ('p', 'print', None, _('print results instead of overwriting LOCAL')), ('', 'no-minimal', None, _('no effect (DEPRECATED)')), ('h', 'help', None, _('display help and exit')), ('q', 'quiet', None, _('suppress output'))] usage = _('''simplemerge [OPTS] LOCAL BASE OTHER Simple three-way file merge utility with a minimal feature set. Apply to LOCAL the changes necessary to go from BASE to OTHER. By default, LOCAL is overwritten with the results of this operation. ''') class ParseError(Exception): """Exception raised on errors in parsing the command line.""" def showhelp(): sys.stdout.write(usage) sys.stdout.write('\noptions:\n') out_opts = [] for shortopt, longopt, default, desc in options: out_opts.append(('%2s%s' % (shortopt and '-%s' % shortopt, longopt and ' --%s' % longopt), '%s' % desc)) opts_len = max([len(opt[0]) for opt in out_opts]) for first, second in out_opts: sys.stdout.write(' %-*s %s\n' % (opts_len, first, second)) try: for fp in (sys.stdin, sys.stdout, sys.stderr): util.setbinary(fp) opts = {} try: args = fancyopts.fancyopts(sys.argv[1:], options, opts) except fancyopts.getopt.GetoptError as e: raise ParseError(e) if opts['help']: showhelp() sys.exit(0) if len(args) != 3: raise ParseError(_('wrong number of arguments')) sys.exit(simplemerge.simplemerge(ui.ui(), *args, **opts)) except ParseError as e: sys.stdout.write("%s: %s\n" % (sys.argv[0], e)) showhelp() sys.exit(1) except error.Abort as e: sys.stderr.write("abort: %s\n" % e) sys.exit(255) except KeyboardInterrupt: sys.exit(255)