Mercurial > hg
view mercurial/lock.py @ 20182:04036798ebed
branches: avoid unnecessary changectx.branch() calls
This requires reading from the changelog, which can be costly over NFS.
Note that this does not totally remove reading from the changelog; we
still do that when calling changectx.closesbranch(). That call will be
removed in a later patch.
Running hg branches on the PyPy repo (with 996) over a busy NFS server,
before this change:
$ time hg --profile branches > /dev/null
CallCount Recursive Total(s) Inline(s) module:lineno(function)
2042 0 2.2827 2.2827 <open>
2036 0 0.9840 0.9840 <method 'close' of 'file' objects>
2036 0 0.0464 0.0464 <method 'read' of 'file' objects>
5233 0 0.1985 0.0453 mercurial.repoview:161(changelog)
10462 0 0.0791 0.0314 mercurial.changelog:133(tip)
5233 0 0.0388 0.0176 mercurial.localrepo:26(__get__)
10462 0 0.0250 0.0126 <len>
5233 0 0.0059 0.0039 mercurial.repoview:112(filterrevs)
10462 0 0.0029 0.0029 <hash>
2034 0 0.0444 0.0444 <method 'seek' of 'file' objects>
5340 0 0.0390 0.0390 mercurial.revlog:296(rev)
2582 0 0.0371 0.0371 <zlib.decompress>
3155 0 0.1963 0.0366 mercurial.context:202(__init__)
3155 0 0.1238 0.0306 mercurial.repoview:161(changelog)
3155 0 0.0261 0.0080 mercurial.changelog:183(rev)
9465 0 0.0061 0.0061 <isinstance>
1096 0 0.0023 0.0023 <binascii.unhexlify>
4251 0 0.0014 0.0014 <len>
2059 0 3.7341 0.0332 mercurial.changelog:270(read)
2059 0 3.6304 0.0307 mercurial.revlog:907(revision)
2057 0 0.0262 0.0137 mercurial.changelog:28(decodeextra)
4118 0 0.0094 0.0094 <method 'split' of 'str' objects>
4118 0 0.0270 0.0048 mercurial.encoding:61(tolocal)
2059 0 0.0040 0.0040 <method 'index' of 'str' objects>
10462 0 0.0791 0.0314 mercurial.changelog:133(tip)
10462 0 0.0289 0.0207 mercurial.changelog:190(node)
10462 0 0.0188 0.0091 <len>
52433 20932 0.0478 0.0310 <len>
20932 0 0.0221 0.0168 mercurial.revlog:262(__len__)
2059 0 3.6304 0.0307 mercurial.revlog:907(revision)
real 0m4.361s
user 0m0.986s
sys 0m0.237s
After this change:
$ time hg --profile branches > /dev/null
CallCount Recursive Total(s) Inline(s) module:lineno(function)
1069 0 1.1098 1.1098 <open>
1063 0 0.4865 0.4865 <method 'close' of 'file' objects>
4122 0 0.1811 0.0404 mercurial.repoview:161(changelog)
8240 0 0.0712 0.0272 mercurial.changelog:133(tip)
4122 0 0.0378 0.0177 mercurial.localrepo:26(__get__)
8240 0 0.0221 0.0115 <len>
4122 0 0.0057 0.0033 mercurial.repoview:112(filterrevs)
8240 0 0.0025 0.0025 <hash>
3029 0 0.1979 0.0371 mercurial.context:202(__init__)
3029 0 0.1278 0.0310 mercurial.repoview:161(changelog)
3029 0 0.0230 0.0081 mercurial.changelog:183(rev)
9087 0 0.0061 0.0061 <isinstance>
1096 0 0.0026 0.0026 <binascii.unhexlify>
4125 0 0.0014 0.0014 <len>
4229 0 0.0337 0.0337 mercurial.revlog:296(rev)
1061 0 0.0296 0.0296 <method 'seek' of 'file' objects>
1063 0 0.0292 0.0292 <method 'read' of 'file' objects>
8240 0 0.0712 0.0272 mercurial.changelog:133(tip)
8240 0 0.0271 0.0196 mercurial.changelog:190(node)
8240 0 0.0169 0.0083 <len>
40476 16488 0.0422 0.0271 <len>
16488 0 0.0193 0.0152 mercurial.revlog:262(__len__)
1342 0 0.0241 0.0241 <zlib.decompress>
9445 0 0.0336 0.0224 mercurial.changelog:190(node)
9445 0 0.0112 0.0112 mercurial.revlog:317(node)
1074 0 1.9102 0.0224 mercurial.changelog:270(read)
1074 0 1.8397 0.0202 mercurial.revlog:907(revision)
1073 0 0.0187 0.0099 mercurial.changelog:28(decodeextra)
2148 0 0.0061 0.0061 <method 'split' of 'str' objects>
2148 0 0.0184 0.0034 mercurial.encoding:61(tolocal)
real 0m2.402s
user 0m0.735s
sys 0m0.177s
author | Brodie Rao <brodie@sf.io> |
---|---|
date | Fri, 15 Nov 2013 23:18:08 -0500 |
parents | abfe6a8e619b |
children | c697b70f295f |
line wrap: on
line source
# lock.py - simple advisory locking scheme for mercurial # # Copyright 2005, 2006 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. import util, error import errno, os, socket, time import warnings class lock(object): '''An advisory lock held by one process to control access to a set of files. Non-cooperating processes or incorrectly written scripts can ignore Mercurial's locking scheme and stomp all over the repository, so don't do that. Typically used via localrepository.lock() to lock the repository store (.hg/store/) or localrepository.wlock() to lock everything else under .hg/.''' # lock is symlink on platforms that support it, file on others. # symlink is used because create of directory entry and contents # are atomic even over nfs. # old-style lock: symlink to pid # new-style lock: symlink to hostname:pid _host = None def __init__(self, vfs, file, timeout=-1, releasefn=None, desc=None): self.vfs = vfs self.f = file self.held = 0 self.timeout = timeout self.releasefn = releasefn self.desc = desc self.postrelease = [] self.pid = os.getpid() self.lock() def __del__(self): if self.held: warnings.warn("use lock.release instead of del lock", category=DeprecationWarning, stacklevel=2) # ensure the lock will be removed # even if recursive locking did occur self.held = 1 self.release() def lock(self): timeout = self.timeout while True: try: self.trylock() return 1 except error.LockHeld, inst: if timeout != 0: time.sleep(1) if timeout > 0: timeout -= 1 continue raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, inst.locker) def trylock(self): if self.held: self.held += 1 return if lock._host is None: lock._host = socket.gethostname() lockname = '%s:%s' % (lock._host, self.pid) while not self.held: try: self.vfs.makelock(lockname, self.f) self.held = 1 except (OSError, IOError), why: if why.errno == errno.EEXIST: locker = self.testlock() if locker is not None: raise error.LockHeld(errno.EAGAIN, self.vfs.join(self.f), self.desc, locker) else: raise error.LockUnavailable(why.errno, why.strerror, why.filename, self.desc) def testlock(self): """return id of locker if lock is valid, else None. If old-style lock, we cannot tell what machine locker is on. with new-style lock, if locker is on this machine, we can see if locker is alive. If locker is on this machine but not alive, we can safely break lock. The lock file is only deleted when None is returned. """ try: locker = self.vfs.readlock(self.f) except (OSError, IOError), why: if why.errno == errno.ENOENT: return None raise try: host, pid = locker.split(":", 1) except ValueError: return locker if host != lock._host: return locker try: pid = int(pid) except ValueError: return locker if util.testpid(pid): return locker # if locker dead, break lock. must do this with another lock # held, or can race and break valid lock. try: l = lock(self.vfs, self.f + '.break', timeout=0) self.vfs.unlink(self.f) l.release() except error.LockError: return locker def release(self): """release the lock and execute callback function if any If the lock has been acquired multiple times, the actual release is delayed to the last release call.""" if self.held > 1: self.held -= 1 elif self.held == 1: self.held = 0 if os.getpid() != self.pid: # we forked, and are not the parent return if self.releasefn: self.releasefn() try: self.vfs.unlink(self.f) except OSError: pass for callback in self.postrelease: callback() def release(*locks): for lock in locks: if lock is not None: lock.release()