mercurial/lock.py
author Matt Mackall <mpm@selenic.com>
Tue, 12 Jul 2005 20:55:42 -0800
changeset 687 44b30755d07c
parent 515 03f27b1381f9
child 704 5ca319a641e1
child 705 574869103985
permissions -rw-r--r--
Hide file hashes in log There are six different kinds of revision numbers and hashes: changeset hash and local number manifest hash and local number file hash and local number We really ought to expose only the changeset hash and local number, so begin hiding the others from the end user manifest hash: 40d07cc930e84a9283d5e03ade23e3454401e148

# 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
import util

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:
            util.makelock(str(pid), self.f)
            self.held = 1
        except:
            raise LockHeld(util.readlock(self.f))

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