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.
# hook.py - hook support for mercurial
#
# Copyright 2007 Matt Mackall <mpm@selenic.com>
#
# 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 os
import sys
import time
from .i18n import _
from . import (
demandimport,
error,
extensions,
util,
)
def _pythonhook(ui, repo, name, hname, funcname, args, throw):
'''call python hook. hook is callable object, looked up as
name in python module. if callable returns "true", hook
fails, else passes. if hook raises exception, treated as
hook failure. exception propagates if throw is "true".
reason for "true" meaning "hook failed" is so that
unmodified commands (e.g. mercurial.commands.update) can
be run as hooks without wrappers to convert return values.'''
if callable(funcname):
obj = funcname
funcname = obj.__module__ + "." + obj.__name__
else:
d = funcname.rfind('.')
if d == -1:
raise util.Abort(_('%s hook is invalid ("%s" not in '
'a module)') % (hname, funcname))
modname = funcname[:d]
oldpaths = sys.path
if util.mainfrozen():
# binary installs require sys.path manipulation
modpath, modfile = os.path.split(modname)
if modpath and modfile:
sys.path = sys.path[:] + [modpath]
modname = modfile
with demandimport.deactivated():
try:
obj = __import__(modname)
except ImportError:
e1 = sys.exc_type, sys.exc_value, sys.exc_traceback
try:
# extensions are loaded with hgext_ prefix
obj = __import__("hgext_%s" % modname)
except ImportError:
e2 = sys.exc_type, sys.exc_value, sys.exc_traceback
if ui.tracebackflag:
ui.warn(_('exception from first failed import '
'attempt:\n'))
ui.traceback(e1)
if ui.tracebackflag:
ui.warn(_('exception from second failed import '
'attempt:\n'))
ui.traceback(e2)
raise util.Abort(_('%s hook is invalid '
'(import of "%s" failed)') %
(hname, modname))
sys.path = oldpaths
try:
for p in funcname.split('.')[1:]:
obj = getattr(obj, p)
except AttributeError:
raise util.Abort(_('%s hook is invalid '
'("%s" is not defined)') %
(hname, funcname))
if not callable(obj):
raise util.Abort(_('%s hook is invalid '
'("%s" is not callable)') %
(hname, funcname))
ui.note(_("calling hook %s: %s\n") % (hname, funcname))
starttime = time.time()
try:
# redirect IO descriptors to the ui descriptors so hooks
# that write directly to these don't mess up the command
# protocol when running through the command server
old = sys.stdout, sys.stderr, sys.stdin
sys.stdout, sys.stderr, sys.stdin = ui.fout, ui.ferr, ui.fin
r = obj(ui=ui, repo=repo, hooktype=name, **args)
except Exception as exc:
if isinstance(exc, util.Abort):
ui.warn(_('error: %s hook failed: %s\n') %
(hname, exc.args[0]))
else:
ui.warn(_('error: %s hook raised an exception: '
'%s\n') % (hname, exc))
if throw:
raise
ui.traceback()
return True
finally:
sys.stdout, sys.stderr, sys.stdin = old
duration = time.time() - starttime
ui.log('pythonhook', 'pythonhook-%s: %s finished in %0.2f seconds\n',
name, funcname, duration)
if r:
if throw:
raise error.HookAbort(_('%s hook failed') % hname)
ui.warn(_('warning: %s hook failed\n') % hname)
return r
def _exthook(ui, repo, name, cmd, args, throw):
ui.note(_("running hook %s: %s\n") % (name, cmd))
starttime = time.time()
env = {}
for k, v in args.iteritems():
if callable(v):
v = v()
if isinstance(v, dict):
# make the dictionary element order stable across Python
# implementations
v = ('{' +
', '.join('%r: %r' % i for i in sorted(v.iteritems())) +
'}')
env['HG_' + k.upper()] = v
if repo:
cwd = repo.root
else:
cwd = os.getcwd()
r = ui.system(cmd, environ=env, cwd=cwd)
duration = time.time() - starttime
ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n',
name, cmd, duration)
if r:
desc, r = util.explainexit(r)
if throw:
raise error.HookAbort(_('%s hook %s') % (name, desc))
ui.warn(_('warning: %s hook %s\n') % (name, desc))
return r
def _allhooks(ui):
hooks = []
for name, cmd in ui.configitems('hooks'):
if not name.startswith('priority'):
priority = ui.configint('hooks', 'priority.%s' % name, 0)
hooks.append((-priority, len(hooks), name, cmd))
return [(k, v) for p, o, k, v in sorted(hooks)]
_redirect = False
def redirect(state):
global _redirect
_redirect = state
def hook(ui, repo, name, throw=False, **args):
if not ui.callhooks:
return False
r = False
oldstdout = -1
try:
for hname, cmd in _allhooks(ui):
if hname.split('.')[0] != name or not cmd:
continue
if oldstdout == -1 and _redirect:
try:
stdoutno = sys.__stdout__.fileno()
stderrno = sys.__stderr__.fileno()
# temporarily redirect stdout to stderr, if possible
if stdoutno >= 0 and stderrno >= 0:
sys.__stdout__.flush()
oldstdout = os.dup(stdoutno)
os.dup2(stderrno, stdoutno)
except (OSError, AttributeError):
# files seem to be bogus, give up on redirecting (WSGI, etc)
pass
if callable(cmd):
r = _pythonhook(ui, repo, name, hname, cmd, args, throw) or r
elif cmd.startswith('python:'):
if cmd.count(':') >= 2:
path, cmd = cmd[7:].rsplit(':', 1)
path = util.expandpath(path)
if repo:
path = os.path.join(repo.root, path)
try:
mod = extensions.loadpath(path, 'hghook.%s' % hname)
except Exception:
ui.write(_("loading %s hook failed:\n") % hname)
raise
hookfn = getattr(mod, cmd)
else:
hookfn = cmd[7:].strip()
r = _pythonhook(ui, repo, name, hname, hookfn, args, throw) or r
else:
r = _exthook(ui, repo, hname, cmd, args, throw) or r
# The stderr is fully buffered on Windows when connected to a pipe.
# A forcible flush is required to make small stderr data in the
# remote side available to the client immediately.
sys.stderr.flush()
finally:
if _redirect and oldstdout >= 0:
os.dup2(oldstdout, stdoutno)
os.close(oldstdout)
return r