Update openstack/common/lockutils

The following commits are in this update:

79e6bc6 fix lockutils.lock() to make it thread-safe
ace5120 Add main() to lockutils that creates temp dir for locks
537d8e2 Allow lockutils to get lock_path conf from envvar

Change-Id: Id50b7c0ccbb417493320e19191a92675fcf126ff

marconi/openstack/common/lockutils.py

@@ -20,6 +20,10 @@ import contextlib
 import errno
 import functools
 import os
+import shutil
+import subprocess
+import sys
+import tempfile
 import threading
 import time
 import weakref
@@ -39,6 +43,7 @@ util_opts = [
     cfg.BoolOpt('disable_process_locking', default=False,
                 help='Whether to disable inter-process locks'),
     cfg.StrOpt('lock_path',
+               default=os.environ.get("MARCONI_LOCK_PATH"),
                help=('Directory to use for lock files.'))
 ]
 
@@ -131,6 +136,7 @@ else:
     InterProcessLock = _PosixLock
 
 _semaphores = weakref.WeakValueDictionary()
+_semaphores_lock = threading.Lock()
 
 
 @contextlib.contextmanager
@@ -153,15 +159,12 @@ def lock(name, lock_file_prefix=None, external=False, lock_path=None):
     special location for external lock files to live. If nothing is set, then
     CONF.lock_path is used as a default.
     """
-    # NOTE(soren): If we ever go natively threaded, this will be racy.
-    #              See http://stackoverflow.com/questions/5390569/dyn
-    #              amically-allocating-and-destroying-mutexes
-    sem = _semaphores.get(name, threading.Semaphore())
-    if name not in _semaphores:
-        # this check is not racy - we're already holding ref locally
-        # so GC won't remove the item and there was no IO switch
-        # (only valid in greenthreads)
-        _semaphores[name] = sem
+    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})
@@ -241,13 +244,14 @@ def synchronized(name, lock_file_prefix=None, external=False, lock_path=None):
     def wrap(f):
         @functools.wraps(f)
         def inner(*args, **kwargs):
-            with lock(name, lock_file_prefix, external, lock_path):
-                LOG.debug(_('Got semaphore / lock "%(function)s"'),
+            try:
+                with lock(name, lock_file_prefix, external, lock_path):
+                    LOG.debug(_('Got semaphore / lock "%(function)s"'),
+                              {'function': f.__name__})
+                    return f(*args, **kwargs)
+            finally:
+                LOG.debug(_('Semaphore / lock released "%(function)s"'),
                           {'function': f.__name__})
-                return f(*args, **kwargs)
-
-            LOG.debug(_('Semaphore / lock released "%(function)s"'),
-                      {'function': f.__name__})
         return inner
     return wrap
 
@@ -275,3 +279,27 @@ def synchronized_with_prefix(lock_file_prefix):
     """
 
     return functools.partial(synchronized, lock_file_prefix=lock_file_prefix)
+
+
+def main(argv):
+    """Create a dir for locks and pass it to command from arguments
+
+    If you run this:
+    python -m openstack.common.lockutils python setup.py testr <etc>
+
+    a temporary directory will be created for all your locks and passed to all
+    your tests in an environment variable. The temporary dir will be deleted
+    afterwards and the return value will be preserved.
+    """
+
+    lock_dir = tempfile.mkdtemp()
+    os.environ["MARCONI_LOCK_PATH"] = lock_dir
+    try:
+        ret_val = subprocess.call(argv[1:])
+    finally:
+        shutil.rmtree(lock_dir, ignore_errors=True)
+    return ret_val
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))