revlog: add option to mmap revlog index
Following on from Jun Wu's patch last October[1], we have found that using mmap
for the revlog index in repos with large revlogs gives a noticable performance
improvment (~110ms on each hg invocation), particularly for commands that don't
touch the index very much.
This changeset adds this as an option, activated by a new experimental config
option so that it can be enabled on a per-repo basis. The configuration option
specifies an index size threshold at which Mercurial will switch to using mmap
to access the index.
If the configuration option is not specified, the default remains to load the
full file, which seems to be the best option for smaller repos.
Some initial performance numbers for average of 5 invocations of `hg log -l 5`
for different cache states:
| Repo: | HG | FB |
|---|---|---|
| Index size: | 2.3MB | much bigger |
| read (warm): | 237ms | 432ms |
| mmap (warm): | 227ms | 321ms |
| | (-3%) | (-26%) |
| read (cold): | 397ms | 696ms |
| mmap (cold): | 410ms | 888ms |
| | (+3%) | (+28%) |
[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-October/088737.html
Test Plan:
`hg log --config experimental.mmapindex=true`
Differential Revision: https://phab.mercurial-scm.org/D477
from __future__ import absolute_import
import array
import errno
import fcntl
import os
import sys
from . import (
encoding,
pycompat,
util,
)
# BSD 'more' escapes ANSI color sequences by default. This can be disabled by
# $MORE variable, but there's no compatible option with Linux 'more'. Given
# OS X is widely used and most modern Unix systems would have 'less', setting
# 'less' as the default seems reasonable.
fallbackpager = 'less'
def _rcfiles(path):
rcs = [os.path.join(path, 'hgrc')]
rcdir = os.path.join(path, 'hgrc.d')
try:
rcs.extend([os.path.join(rcdir, f)
for f, kind in util.listdir(rcdir)
if f.endswith(".rc")])
except OSError:
pass
return rcs
def systemrcpath():
path = []
if pycompat.sysplatform == 'plan9':
root = 'lib/mercurial'
else:
root = 'etc/mercurial'
# old mod_python does not set sys.argv
if len(getattr(sys, 'argv', [])) > 0:
p = os.path.dirname(os.path.dirname(pycompat.sysargv[0]))
if p != '/':
path.extend(_rcfiles(os.path.join(p, root)))
path.extend(_rcfiles('/' + root))
return path
def userrcpath():
if pycompat.sysplatform == 'plan9':
return [encoding.environ['home'] + '/lib/hgrc']
elif pycompat.sysplatform == 'darwin':
return [os.path.expanduser('~/.hgrc')]
else:
confighome = encoding.environ.get('XDG_CONFIG_HOME')
if confighome is None or not os.path.isabs(confighome):
confighome = os.path.expanduser('~/.config')
return [os.path.expanduser('~/.hgrc'),
os.path.join(confighome, 'hg', 'hgrc')]
def termsize(ui):
try:
import termios
TIOCGWINSZ = termios.TIOCGWINSZ # unavailable on IRIX (issue3449)
except (AttributeError, ImportError):
return 80, 24
for dev in (ui.ferr, ui.fout, ui.fin):
try:
try:
fd = dev.fileno()
except AttributeError:
continue
if not os.isatty(fd):
continue
arri = fcntl.ioctl(fd, TIOCGWINSZ, '\0' * 8)
height, width = array.array(r'h', arri)[:2]
if width > 0 and height > 0:
return width, height
except ValueError:
pass
except IOError as e:
if e[0] == errno.EINVAL:
pass
else:
raise
return 80, 24