Mercurial > hg > mercurial-crew-with-dirclash
view mercurial/lock.py @ 5440:f9b0e4f023c4
findcopies: fix rename bug
We've fiddled with this line several times, and an old bug has
reappeared from it. Let's take a peek at the history.
The original "or" (rev 3674, in 0.9.2 and 0.9.3):
http://www.selenic.com/hg/rev/9103dab96093
Then I changed it to an "and" to fix a bug (rev 4304):
http://www.selenic.com/hg/rev/4787e2b0dd03
Then for reasons now lost in the mists of time, I dropped half (rev 4399):
http://www.selenic.com/hg/rev/93652499bed3
Then we added back the "or" (rev 4416, in 0.9.4):
http://www.selenic.com/hg/rev/bb1800a7d7e1
So it seems it ought to be "and".
author | Matt Mackall <mpm@selenic.com> |
---|---|
date | Mon, 08 Oct 2007 18:47:22 -0500 |
parents | abaee83ce0a6 |
children | 3e25a6eb5c9a |
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# lock.py - simple 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, incorporated herein by reference. import errno, os, socket, time, util class LockException(IOError): def __init__(self, errno, strerror, filename, desc): IOError.__init__(self, errno, strerror, filename) self.desc = desc class LockHeld(LockException): def __init__(self, errno, filename, desc, locker): LockException.__init__(self, errno, 'Lock held', filename, desc) self.locker = locker class LockUnavailable(LockException): pass class lock(object): # 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 def __init__(self, file, timeout=-1, releasefn=None, desc=None): self.f = file self.held = 0 self.timeout = timeout self.releasefn = releasefn self.id = None self.host = None self.pid = None self.desc = desc self.lock() def __del__(self): self.release() def lock(self): timeout = self.timeout while 1: try: self.trylock() return 1 except LockHeld, inst: if timeout != 0: time.sleep(1) if timeout > 0: timeout -= 1 continue raise LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, inst.locker) def trylock(self): if self.id is None: self.host = socket.gethostname() self.pid = os.getpid() self.id = '%s:%s' % (self.host, self.pid) while not self.held: try: util.makelock(self.id, self.f) self.held = 1 except (OSError, IOError), why: if why.errno == errno.EEXIST: locker = self.testlock() if locker is not None: raise LockHeld(errno.EAGAIN, self.f, self.desc, locker) else: raise 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 != self.host: return locker try: pid = int(pid) except: 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') l.trylock() os.unlink(self.f) l.release() except (LockHeld, LockUnavailable): return locker def release(self): if self.held: self.held = 0 if self.releasefn: self.releasefn() try: os.unlink(self.f) except: pass