Mercurial > hg
view mercurial/lock.py @ 2161:12e11413ca19
Fix just introduced possible old-http bug
My last patch changed httprangereader.read to read only the specified
amount of data from the connection, to prevent it from returning more
than what was asked.
I just realized that this could lead to the connection not being closed.
In practice, it looks like the connection is closed just fine, but it's
probably safer to read everything and then return only what's necessary.
author | Alexis S. L. Carvalho <alexis@cecm.usp.br> |
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date | Sun, 30 Apr 2006 18:50:53 +0200 |
parents | ff5c9a92f556 |
children | 0875cda033fd |
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# lock.py - simple locking scheme for mercurial # # Copyright 2005 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. from demandload import * demandload(globals(), '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: 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. locker = util.readlock(self.f) c = locker.find(':') if c == -1: return locker host = locker[:c] if host != self.host: return locker try: pid = int(locker[c+1:]) 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