Mercurial > hg > mercurial-crew-with-dirclash
view mercurial/lock.py @ 2569:2264b2b077a1
run-tests.py: make tests use same python interpreter as test harness.
this is wanted because some tests run python interpreter directly.
must use same python interpreter in tests as in main harness or problems
will happen because of e.g. different python abi if run-tests.py run
with python 2.5 but system python is 2.4.
fix is to see if system python is used and is named python. if no,
put symlink called python at front of shell search path.
author | Vadim Gelfer <vadim.gelfer@gmail.com> |
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date | Thu, 06 Jul 2006 10:09:24 -0700 |
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