Mercurial > hg
view mercurial/lock.py @ 15063:c20688b7c061 stable
setdiscovery: fix hang when #heads>200 (issue2971)
When setting up the next sample, we always add all of the heads, regardless
of the desired max sample size. But if the number of heads exceeds this
size, then we don't add any more nodes from the still undecided set.
(This is debatable per se, and I'll investigate it, but it's how we designed
it at the moment.)
The bug was that we always added the overall heads, not the heads of the
remaining undecided set. Thus, if #heads>200 (desired sample size), we
did not make progress any longer.
author | Peter Arrenbrecht <peter.arrenbrecht@gmail.com> |
---|---|
date | Thu, 25 Aug 2011 21:25:14 +0200 |
parents | 1ffeeb91c55d |
children | 926a06f7a353 |
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# 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, file, timeout=-1, releasefn=None, desc=None): self.f = file self.held = 0 self.timeout = timeout self.releasefn = releasefn self.desc = desc 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, os.getpid()) while not self.held: try: util.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.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. """ locker = util.readlock(self.f) 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.f + '.break', timeout=0) util.unlink(self.f) l.release() except error.LockError: return locker def release(self): if self.held > 1: self.held -= 1 elif self.held == 1: self.held = 0 if self.releasefn: self.releasefn() try: util.unlink(self.f) except OSError: pass def release(*locks): for lock in locks: if lock is not None: lock.release()