##// END OF EJS Templates
snapshot: search for unrelated but reusable full-snapshot...
snapshot: search for unrelated but reusable full-snapshot # New Strategy Step: Reusing Snapshot Outside Of Parents' Chain. If no suitable bases were found in the parent's chains, see if we could reuse a full snapshot not directly related to the current revision. Such search can be expensive, so we only search for snapshots appended to the revlog *after* the bases used by the parents of the current revision (the one we just tested). We assume the parent's bases were created because the previous snapshots were unsuitable, so there are low odds they would be useful now. This search gives a chance to reuse a delta chain unrelated to the current revision. Without this re-use, topological branches would keep reopening new full chains. Creating more and more snapshots as the repository grow. In repositories with many topological branches, the lack of delta reuse can create too many snapshots reducing overall compression to nothing. This results in a very large repository and other usability issues. For now, we still focus on creating level-1 snapshots. However, this principle will play a large part in how we avoid snapshot explosion once we have more snapshot levels. # Effects On The Test Repository In the test repository we created, we can see the beneficial effect of such reuse. We need very few level-0 snapshots and the overall revlog size has decreased. The `hg debugrevlog` call, show a "lvl-2" snapshot. It comes from the existing delta logic using the `prev` revision (revlog's tip) as the base. In this specific case, it turns out the tip was a level-1 snapshot. This is a coincidence that can be ignored. Finding and testing against all these unrelated snapshots can have a performance impact at write time. We currently focus on building good deltas chain we build. Performance concern will be dealt with later in another series.

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server.py
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# server.py - utility and factory of server
#
# Copyright 2005-2007 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
from .i18n import _
from . import (
chgserver,
cmdutil,
commandserver,
error,
hgweb,
pycompat,
util,
)
from .utils import (
procutil,
)
def runservice(opts, parentfn=None, initfn=None, runfn=None, logfile=None,
runargs=None, appendpid=False):
'''Run a command as a service.'''
postexecargs = {}
if opts['daemon_postexec']:
for inst in opts['daemon_postexec']:
if inst.startswith('unlink:'):
postexecargs['unlink'] = inst[7:]
elif inst.startswith('chdir:'):
postexecargs['chdir'] = inst[6:]
elif inst != 'none':
raise error.Abort(_('invalid value for --daemon-postexec: %s')
% inst)
# When daemonized on Windows, redirect stdout/stderr to the lockfile (which
# gets cleaned up after the child is up and running), so that the parent can
# read and print the error if this child dies early. See 594dd384803c. On
# other platforms, the child can write to the parent's stdio directly, until
# it is redirected prior to runfn().
if pycompat.iswindows and opts['daemon_postexec']:
if 'unlink' in postexecargs and os.path.exists(postexecargs['unlink']):
procutil.stdout.flush()
procutil.stderr.flush()
fd = os.open(postexecargs['unlink'],
os.O_WRONLY | os.O_APPEND | os.O_BINARY)
try:
os.dup2(fd, procutil.stdout.fileno())
os.dup2(fd, procutil.stderr.fileno())
finally:
os.close(fd)
def writepid(pid):
if opts['pid_file']:
if appendpid:
mode = 'ab'
else:
mode = 'wb'
fp = open(opts['pid_file'], mode)
fp.write('%d\n' % pid)
fp.close()
if opts['daemon'] and not opts['daemon_postexec']:
# Signal child process startup with file removal
lockfd, lockpath = pycompat.mkstemp(prefix='hg-service-')
os.close(lockfd)
try:
if not runargs:
runargs = procutil.hgcmd() + pycompat.sysargv[1:]
runargs.append('--daemon-postexec=unlink:%s' % lockpath)
# Don't pass --cwd to the child process, because we've already
# changed directory.
for i in pycompat.xrange(1, len(runargs)):
if runargs[i].startswith('--cwd='):
del runargs[i]
break
elif runargs[i].startswith('--cwd'):
del runargs[i:i + 2]
break
def condfn():
return not os.path.exists(lockpath)
pid = procutil.rundetached(runargs, condfn)
if pid < 0:
# If the daemonized process managed to write out an error msg,
# report it.
if pycompat.iswindows and os.path.exists(lockpath):
with open(lockpath, 'rb') as log:
for line in log:
procutil.stderr.write(line)
raise error.Abort(_('child process failed to start'))
writepid(pid)
finally:
util.tryunlink(lockpath)
if parentfn:
return parentfn(pid)
else:
return
if initfn:
initfn()
if not opts['daemon']:
writepid(procutil.getpid())
if opts['daemon_postexec']:
try:
os.setsid()
except AttributeError:
pass
if 'chdir' in postexecargs:
os.chdir(postexecargs['chdir'])
procutil.hidewindow()
procutil.stdout.flush()
procutil.stderr.flush()
nullfd = os.open(os.devnull, os.O_RDWR)
logfilefd = nullfd
if logfile:
logfilefd = os.open(logfile, os.O_RDWR | os.O_CREAT | os.O_APPEND,
0o666)
os.dup2(nullfd, procutil.stdin.fileno())
os.dup2(logfilefd, procutil.stdout.fileno())
os.dup2(logfilefd, procutil.stderr.fileno())
stdio = (procutil.stdin.fileno(), procutil.stdout.fileno(),
procutil.stderr.fileno())
if nullfd not in stdio:
os.close(nullfd)
if logfile and logfilefd not in stdio:
os.close(logfilefd)
# Only unlink after redirecting stdout/stderr, so Windows doesn't
# complain about a sharing violation.
if 'unlink' in postexecargs:
os.unlink(postexecargs['unlink'])
if runfn:
return runfn()
_cmdservicemap = {
'chgunix': chgserver.chgunixservice,
'pipe': commandserver.pipeservice,
'unix': commandserver.unixforkingservice,
}
def _createcmdservice(ui, repo, opts):
mode = opts['cmdserver']
try:
return _cmdservicemap[mode](ui, repo, opts)
except KeyError:
raise error.Abort(_('unknown mode %s') % mode)
def _createhgwebservice(ui, repo, opts):
# this way we can check if something was given in the command-line
if opts.get('port'):
opts['port'] = util.getport(opts.get('port'))
alluis = {ui}
if repo:
baseui = repo.baseui
alluis.update([repo.baseui, repo.ui])
else:
baseui = ui
webconf = opts.get('web_conf') or opts.get('webdir_conf')
if webconf:
if opts.get('subrepos'):
raise error.Abort(_('--web-conf cannot be used with --subrepos'))
# load server settings (e.g. web.port) to "copied" ui, which allows
# hgwebdir to reload webconf cleanly
servui = ui.copy()
servui.readconfig(webconf, sections=['web'])
alluis.add(servui)
elif opts.get('subrepos'):
servui = ui
# If repo is None, hgweb.createapp() already raises a proper abort
# message as long as webconf is None.
if repo:
webconf = dict()
cmdutil.addwebdirpath(repo, "", webconf)
else:
servui = ui
optlist = ("name templates style address port prefix ipv6"
" accesslog errorlog certificate encoding")
for o in optlist.split():
val = opts.get(o, '')
if val in (None, ''): # should check against default options instead
continue
for u in alluis:
u.setconfig("web", o, val, 'serve')
app = hgweb.createapp(baseui, repo, webconf)
return hgweb.httpservice(servui, app, opts)
def createservice(ui, repo, opts):
if opts["cmdserver"]:
return _createcmdservice(ui, repo, opts)
else:
return _createhgwebservice(ui, repo, opts)