view upmana/mercurial/lock.py @ 248:1df5912db00c beta tip

Traipse Beta 'OpenRPG' {101205-00} Traipse is a distribution of OpenRPG that is designed to be easy to setup and go. Traipse also makes it easy for developers to work on code without fear of sacrifice. 'Ornery-Orc' continues the trend of 'Grumpy' and adds fixes to the code. 'Ornery-Orc's main goal is to offer more advanced features and enhance the productivity of the user. Update Summary (Closed) New Features: New to Map, can re-order Grid, Miniatures, and Whiteboard layer draw order New to Server GUI, can now clear log New Earthdawn Dieroller New IronClaw roller, sheet, and image New ShapeShifter PC Sheet Updates: Update to Warhammer PC Sheet. Rollers set as macros. Should work with little maintanence. Update to Browser Server window. Display rooms with ' " & cleaner Update to Server. Handles ' " & cleaner Update to Dieroller. Cleaner, more effecient expression system Update to Hidden Die plugin, allows for non standard dice rolls Update to location.py, allows for more portable references when starting Traipse Update to the Features node Fixes: Fix to InterParse that was causing an Infernal Loop with Namespace Internal Fix to XML data, removed old Minidom and switched to Element Tree Fix to Server that was causing eternal attempt to find a Server ID, in Register Rooms thread Fix to Server, removing wxPython dependencies where not needed Fix to metaservers.xml file not being created Fix to Single and Double quotes in Whiteboard text Fix to Background images not showing when using the Image Server Fix to Duplicate chat names appearing Fix to Server GUI's logging output Fix to FNB.COLORFUL_TABS bug Fix to Gametree for XSLT Sheets Fix to Gametree for locating gametree files Fix to Send to Chat from Gametree Fix to Gametree, renaming and remapping operates correctly Fix to aliaslib, prevents error caused when SafeHTML is sent None
author sirebral
date Sun, 05 Dec 2010 10:53:30 -0600
parents dcf4fbe09b70
children
line wrap: on
line source

# lock.py - simple locking scheme for mercurial
#
# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2, incorporated herein by reference.

import util, error
import errno, os, socket, time
import warnings

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

    _host = None

    def __init__(self, file, timeout=-1, releasefn=None, desc=None):
        self.f = file
        self.held = 0
        self.timeout = timeout
        self.releasefn = releasefn
        self.desc = desc
        self.lock()

    def __del__(self):
        if self.held:
            warnings.warn("use lock.release instead of del lock",
                    category=DeprecationWarning,
                    stacklevel=2)

            # ensure the lock will be removed
            # even if recursive locking did occur
            self.held = 1

        self.release()

    def lock(self):
        timeout = self.timeout
        while 1:
            try:
                self.trylock()
                return 1
            except error.LockHeld, inst:
                if timeout != 0:
                    time.sleep(1)
                    if timeout > 0:
                        timeout -= 1
                    continue
                raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc,
                                     inst.locker)

    def trylock(self):
        if self.held:
            self.held += 1
            return
        if lock._host is None:
            lock._host = socket.gethostname()
        lockname = '%s:%s' % (lock._host, os.getpid())
        while not self.held:
            try:
                util.makelock(lockname, self.f)
                self.held = 1
            except (OSError, IOError), why:
                if why.errno == errno.EEXIST:
                    locker = self.testlock()
                    if locker is not None:
                        raise error.LockHeld(errno.EAGAIN, self.f, self.desc,
                                             locker)
                else:
                    raise error.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.

        The lock file is only deleted when None is returned.

        """
        locker = util.readlock(self.f)
        try:
            host, pid = locker.split(":", 1)
        except ValueError:
            return locker
        if host != lock._host:
            return locker
        try:
            pid = int(pid)
        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 error.LockError:
            return locker

    def release(self):
        if self.held > 1:
            self.held -= 1
        elif self.held is 1:
            self.held = 0
            if self.releasefn:
                self.releasefn()
            try:
                os.unlink(self.f)
            except: pass

def release(*locks):
    for lock in locks:
        if lock is not None:
            lock.release()