@contextlib.contextmanager
def lock(name, lock_file_prefix=None, external=False, lock_path=None):
    with _semaphores_lock:
        try:
            sem = _semaphores[name]
        except KeyError:
            sem = threading.Semaphore()
            _semaphores[name] = sem

    with sem:
        LOG.debug(_('Got semaphore "%(lock)s"'), {'lock': name})

        # NOTE(mikal): I know this looks odd
        if not hasattr(local.strong_store, 'locks_held'):
            local.strong_store.locks_held = []
        local.strong_store.locks_held.append(name)

        try:
            if external and not CONF.disable_process_locking:
                LOG.debug(_('Attempting to grab file lock "%(lock)s"'),
                          {'lock': name})

                # We need a copy of lock_path because it is non-local
                local_lock_path = lock_path or CONF.lock_path
                if not local_lock_path:
                    raise cfg.RequiredOptError('lock_path')

                if not os.path.exists(local_lock_path):
                    fileutils.ensure_tree(local_lock_path)
                    LOG.info(_('Created lock path: %s'), local_lock_path)

                def add_prefix(name, prefix):
                    if not prefix:
                        return name
                    sep = '' if prefix.endswith('-') else '-'
                    return '%s%s%s' % (prefix, sep, name)

                # NOTE(mikal): the lock name cannot contain directory
                # separators
                lock_file_name = add_prefix(name.replace(os.sep, '_'),
                                            lock_file_prefix)

                lock_file_path = os.path.join(local_lock_path, lock_file_name)

                try:
                    lock = InterProcessLock(lock_file_path)
                    with lock as lock:
                        LOG.debug(_('Got file lock "%(lock)s" at %(path)s'),
                                  {'lock': name, 'path': lock_file_path})
                        yield lock
                finally:
                    LOG.debug(_('Released file lock "%(lock)s" at %(path)s'),
                              {'lock': name, 'path': lock_file_path})
            else:
                yield sem

        finally:
            local.strong_store.locks_held.remove(name)
Processes an incoming BCP 'error' command.
dataset/ETHPy150Open openstack/rack/rack/openstack/common/lockutils.py/lock--crossover with--dataset/ETHPy150Open missionpinball/mpf/mpf/media_controller/core/media_controller.py/MediaController.bcp_error