mercurial/lock.py
author mpm@selenic.com
Tue, 21 Jun 2005 18:41:57 -0800
changeset 407 0e0d0670b2bc
parent 161 0b4c5cb953d9
child 422 10c43444a38e
child 429 688d03d6997a
permissions -rw-r--r--
[PATCH] Merging identical changes from another branch -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [PATCH] Merging identical changes from another branch From: Michael A Fetterman <Michael.Fetterman@cl.cam.ac.uk> The issue comes up when a local uncommitted *new* file (i.e. not in the current manifest) is being merged with an identical file from a branch. Since the file is not in the current manifest (it's either in the current "to-be-added" list, or in the "unknown" state), there's no (local) node from which to create a mergepoint. manifest hash: 4e64ce654a6473524789a97bbaf8bff61b4343af -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCuM/1ywK+sNU5EO8RAn7xAKCJoH/CgzVK4h4xPJDrd2lY9XOINACgmt01 92uuMswZXcoCchQAaxew7C0= =qRsk -----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)