mercurial/lock.py
author mpm@selenic.com
Mon, 13 Jun 2005 12:01:12 -0800
changeset 323 c6f0673ab7e9
parent 161 0b4c5cb953d9
child 422 10c43444a38e
child 429 688d03d6997a
permissions -rw-r--r--
lazyparser speed ups -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 lazyparser speed ups When we do __contains__ on a map, we might as well load the whole index. Not doing this was slowing down finding new changesets quite by a factor of 20. When we do a full load, we also attempt to replace the revlog's index and nodemap with normal Python objects to avoid the lazymap overhead. manifest hash: 9b2b20aacc508f9027d115426c63a381d28e5485 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCreYIywK+sNU5EO8RAoNHAJ9+LmXqsTQb9Bh3mZHq0A0VfQOleQCffHmn jC/O0vnfx5FCRsX2bUFG794= =BDTz -----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)