diff options
Diffstat (limited to 'nova/utils.py')
| -rw-r--r-- | nova/utils.py | 44 |
1 files changed, 43 insertions, 1 deletions
diff --git a/nova/utils.py b/nova/utils.py index e375f11e5..a23feea73 100644 --- a/nova/utils.py +++ b/nova/utils.py @@ -36,12 +36,14 @@ import socket import struct import sys import tempfile +import threading import time import types import uuid import warnings from xml.sax import saxutils +from eventlet import corolocal from eventlet import event from eventlet import greenthread from eventlet import semaphore @@ -838,6 +840,33 @@ else: anyjson.force_implementation("nova.utils") +class GreenLockFile(lockfile.FileLock): + """Implementation of lockfile that allows for a lock per greenthread. + + Simply implements lockfile:LockBase init with an addiontall suffix + on the unique name of the greenthread identifier + """ + def __init__(self, path, threaded=True): + self.path = path + self.lock_file = os.path.abspath(path) + ".lock" + self.hostname = socket.gethostname() + self.pid = os.getpid() + if threaded: + t = threading.current_thread() + # Thread objects in Python 2.4 and earlier do not have ident + # attrs. Worm around that. + ident = getattr(t, "ident", hash(t)) + gident = corolocal.get_ident() + self.tname = "-%x-%x" % (ident & 0xffffffff, gident & 0xffffffff) + else: + self.tname = "" + dirname = os.path.dirname(self.lock_file) + self.unique_name = os.path.join(dirname, + "%s%s.%s" % (self.hostname, + self.tname, + self.pid)) + + _semaphores = {} @@ -869,6 +898,19 @@ def synchronized(name, external=False): a method decorated with @synchronized('mylock', external=True), only one of them will execute at a time. + Important limitation: you can only have one external lock running per + thread at a time. For example the following will fail: + + @utils.synchronized('testlock1', external=True) + def outer_lock(): + + @utils.synchronized('testlock2', external=True) + def inner_lock(): + pass + inner_lock() + + outer_lock() + """ def wrap(f): @@ -893,7 +935,7 @@ def synchronized(name, external=False): {'lock': name, 'method': f.__name__}) lock_file_path = os.path.join(FLAGS.lock_path, 'nova-%s' % name) - lock = lockfile.FileLock(lock_file_path) + lock = GreenLockFile(lock_file_path) with lock: LOG.debug(_('Got file lock "%(lock)s" for ' 'method "%(method)s"...') % |