mercurial/lock.py
author mpm@selenic.com
Fri, 10 Jun 2005 00:26:29 -0800
changeset 301 5add718d92db
parent 161 0b4c5cb953d9
child 422 10c43444a38e
child 429 688d03d6997a
permissions -rw-r--r--
revlog: allow duplicates -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 revlog: allow duplicates If two branches make the same change to the same parent, the result will be an identical hash. Git apparently does this all the time. Deal with it gracefully. manifest hash: c6217eab4b310e1ae529dd75ab90e717dbe5d55d -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCqU61ywK+sNU5EO8RAkFqAJ9KhWUQgjZbzzB/+mTkolH0GkT1awCfa+Mj ulbI4xCRZcvfQE492mcNwQA= =N6In -----END PGP SIGNATURE-----

# 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.

import os, time

class LockHeld(Exception):
    pass

class lock:
    def __init__(self, file, wait = 1):
        self.f = file
        self.held = 0
        self.wait = wait
        self.lock()

    def __del__(self):
        self.release()

    def lock(self):
        while 1:
            try:
                self.trylock()
                return 1
            except LockHeld, inst:
                if self.wait:
                    time.sleep(1)
                    continue
                raise inst
        
    def trylock(self):
        pid = os.getpid()
        try:
            os.symlink(str(pid), self.f)
            self.held = 1
        except:
            raise LockHeld(os.readlink(self.f))

    def release(self):
        if self.held:
            self.held = 0
            os.unlink(self.f)