Mercurial > hg
view mercurial/config.py @ 26379:39d643252b9f
revlog: use existing file handle when reading during _addrevision
_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.
If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.
After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.
On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:
Call Before After Delta
write 827,639 673,390 -154,249
open 700,103 684,089 -16,014
read 74,489 74,489 0
fstat 493,924 461,896 -32,028
close 249,131 233,117 -16,014
stat 242,001 242,001 0
lstat 18,676 18,676 0
lseek 20,268 20,268 0
ioctl 14,652 13,173 -1,479
TOTAL 3,180,758 2,930,679 -250,079
It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().
Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.
On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.
Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 27 Sep 2015 16:08:18 -0700 |
parents | a027a0813b44 |
children | e70c97cc9243 |
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# config.py - configuration parsing for Mercurial # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import errno import os from .i18n import _ from . import ( error, util, ) class config(object): def __init__(self, data=None, includepaths=[]): self._data = {} self._source = {} self._unset = [] self._includepaths = includepaths if data: for k in data._data: self._data[k] = data[k].copy() self._source = data._source.copy() def copy(self): return config(self) def __contains__(self, section): return section in self._data def __getitem__(self, section): return self._data.get(section, {}) def __iter__(self): for d in self.sections(): yield d def update(self, src): for s, n in src._unset: if s in self and n in self._data[s]: del self._data[s][n] del self._source[(s, n)] for s in src: if s not in self: self._data[s] = util.sortdict() self._data[s].update(src._data[s]) self._source.update(src._source) def get(self, section, item, default=None): return self._data.get(section, {}).get(item, default) def backup(self, section, item): """return a tuple allowing restore to reinstall a previous value The main reason we need it is because it handles the "no data" case. """ try: value = self._data[section][item] source = self.source(section, item) return (section, item, value, source) except KeyError: return (section, item) def source(self, section, item): return self._source.get((section, item), "") def sections(self): return sorted(self._data.keys()) def items(self, section): return self._data.get(section, {}).items() def set(self, section, item, value, source=""): if section not in self: self._data[section] = util.sortdict() self._data[section][item] = value if source: self._source[(section, item)] = source def restore(self, data): """restore data returned by self.backup""" if len(data) == 4: # restore old data section, item, value, source = data self._data[section][item] = value self._source[(section, item)] = source else: # no data before, remove everything section, item = data if section in self._data: self._data[section].pop(item, None) self._source.pop((section, item), None) def parse(self, src, data, sections=None, remap=None, include=None): sectionre = util.re.compile(r'\[([^\[]+)\]') itemre = util.re.compile(r'([^=\s][^=]*?)\s*=\s*(.*\S|)') contre = util.re.compile(r'\s+(\S|\S.*\S)\s*$') emptyre = util.re.compile(r'(;|#|\s*$)') commentre = util.re.compile(r'(;|#)') unsetre = util.re.compile(r'%unset\s+(\S+)') includere = util.re.compile(r'%include\s+(\S|\S.*\S)\s*$') section = "" item = None line = 0 cont = False for l in data.splitlines(True): line += 1 if line == 1 and l.startswith('\xef\xbb\xbf'): # Someone set us up the BOM l = l[3:] if cont: if commentre.match(l): continue m = contre.match(l) if m: if sections and section not in sections: continue v = self.get(section, item) + "\n" + m.group(1) self.set(section, item, v, "%s:%d" % (src, line)) continue item = None cont = False m = includere.match(l) if m and include: expanded = util.expandpath(m.group(1)) includepaths = [os.path.dirname(src)] + self._includepaths for base in includepaths: inc = os.path.normpath(os.path.join(base, expanded)) try: include(inc, remap=remap, sections=sections) break except IOError as inst: if inst.errno != errno.ENOENT: raise error.ParseError(_("cannot include %s (%s)") % (inc, inst.strerror), "%s:%s" % (src, line)) continue if emptyre.match(l): continue m = sectionre.match(l) if m: section = m.group(1) if remap: section = remap.get(section, section) if section not in self: self._data[section] = util.sortdict() continue m = itemre.match(l) if m: item = m.group(1) cont = True if sections and section not in sections: continue self.set(section, item, m.group(2), "%s:%d" % (src, line)) continue m = unsetre.match(l) if m: name = m.group(1) if sections and section not in sections: continue if self.get(section, name) is not None: del self._data[section][name] self._unset.append((section, name)) continue raise error.ParseError(l.rstrip(), ("%s:%s" % (src, line))) def read(self, path, fp=None, sections=None, remap=None): if not fp: fp = util.posixfile(path) self.parse(path, fp.read(), sections, remap, self.read)