diff options
Diffstat (limited to 'Mailman/flock.py')
| -rw-r--r-- | Mailman/flock.py | 140 |
1 files changed, 76 insertions, 64 deletions
diff --git a/Mailman/flock.py b/Mailman/flock.py index 53715ad34..e4d4ef3ee 100644 --- a/Mailman/flock.py +++ b/Mailman/flock.py @@ -37,69 +37,81 @@ NotLockedError = "NotLockedError" TimeOutError = "TimeOutError" class FileLock: - def __init__(self, lockfile, hung_timeout = DEFAULT_HUNG_TIMEOUT, - sleep_interval = DEFAULT_SLEEP_INTERVAL): - self.lockfile = lockfile - self.hung_timeout = hung_timeout - self.sleep_interval = sleep_interval - self.tmpfname = "%s.%s.%d" % (lockfile, socket.gethostname(), os.getpid()) - self.is_locked = 0 - if not os.path.exists(self.lockfile): - try: - file = open(self.lockfile, "w+") - except IOError: - pass + def __init__(self, lockfile, hung_timeout = DEFAULT_HUNG_TIMEOUT, + sleep_interval = DEFAULT_SLEEP_INTERVAL): + self.lockfile = lockfile + self.hung_timeout = hung_timeout + self.sleep_interval = sleep_interval + self.tmpfname = "%s.%s.%d" % (lockfile, socket.gethostname(), + os.getpid()) + self.is_locked = 0 + if not os.path.exists(self.lockfile): + try: + file = open(self.lockfile, "w+") + except IOError: + pass - # Note that no one new can grab the lock once we've opened our - # tmpfile until we close it, even if we don't have the lock. So - # checking the PID and stealing the lock are garunteed to be atomic. - def lock(self, timeout = 0): - """Blocks until the lock can be obtained. Raises a TimeOutError - exception if a positive timeout value is given and that time - elapses before the lock is obtained. - """ - if timeout > 0: - timeout_time = time.time() + timeout - last_pid = -1 - if self.locked(): - raise AlreadyCalledLockError - while 1: - os.link(self.lockfile, self.tmpfname) - if os.stat(self.tmpfname)[3] == 2: - file = open(self.tmpfname, 'w+') - file.write(`os.getpid(),self.tmpfname`) - file.close() - self.is_locked = 1 - break - if timeout and timeout_time < time.time(): - raise TimeOutError - file = open(self.tmpfname, 'r') - try: - pid,winner = eval(file.read()) - except SyntaxError: # no info in file... *can* happen - file.close() - os.unlink(self.tmpfname) - continue - file.close() - if pid <> last_pid: - last_pid = pid - stime = time.time() - if (stime + self.hung_timeout < time.time()) and self.hung_timeout > 0: - file = open(self.tmpfname, 'w+') - file.write(`os.getpid(),self.tmpfname`) - try: - os.unlink(winner) - except os.error: - pass + # Note that no one new can grab the lock once we've opened our tmpfile + # until we close it, even if we don't have the lock. So checking the PID + # and stealing the lock are garunteed to be atomic. + def lock(self, timeout = 0): + """Blocks until the lock can be obtained. + + Raises a TimeOutError exception if a positive timeout value is given + and that time elapses before the lock is obtained. + + """ + if timeout > 0: + timeout_time = time.time() + timeout + last_pid = -1 + if self.locked(): + raise AlreadyCalledLockError + while 1: + os.link(self.lockfile, self.tmpfname) + if os.stat(self.tmpfname)[3] == 2: + file = open(self.tmpfname, 'w+') + file.write(`os.getpid(),self.tmpfname`) + file.close() + self.is_locked = 1 + break + if timeout and timeout_time < time.time(): + raise TimeOutError + file = open(self.tmpfname, 'r') + try: + pid,winner = eval(file.read()) + except SyntaxError: # no info in file... *can* happen + file.close() + os.unlink(self.tmpfname) + continue + file.close() + if pid <> last_pid: + last_pid = pid + stime = time.time() + if (stime + self.hung_timeout < time.time()) and \ + self.hung_timeout > 0: + # then + file = open(self.tmpfname, 'w+') + file.write(`os.getpid(),self.tmpfname`) + try: + os.unlink(winner) + except os.error: + pass + try: + os.unlink(self.tmpfname) + except os.error, (errno, msg): + # XXX: better debugging + msg = msg + ': ' + self.tmpfname + raise os.error, (errno, msg) + continue + os.unlink(self.tmpfname) + time.sleep(self.sleep_interval) + + # This could error if the lock is stolen. You must catch it. + def unlock(self): + if not self.locked(): + raise NotLockedError + self.is_locked = 0 os.unlink(self.tmpfname) - continue - os.unlink(self.tmpfname) - time.sleep(self.sleep_interval) - # This could error if the lock is stolen. You must catch it. - def unlock(self): - if not self.locked(): - raise NotLockedError - self.is_locked = 0 - os.unlink(self.tmpfname) - def locked(self): - return os.path.exists(self.tmpfname) and self.is_locked
\ No newline at end of file + + def locked(self): + return os.path.exists(self.tmpfname) and self.is_locked |