Merge "Update openstack/common/lockutils"
diff --git a/tempest/openstack/common/lockutils.py b/tempest/openstack/common/lockutils.py
index 8ea8766..65f3548 100644
--- a/tempest/openstack/common/lockutils.py
+++ b/tempest/openstack/common/lockutils.py
@@ -20,6 +20,10 @@
 import errno
 import functools
 import os
+import shutil
+import subprocess
+import sys
+import tempfile
 import threading
 import time
 import weakref
@@ -39,6 +43,7 @@
     cfg.BoolOpt('disable_process_locking', default=False,
                 help='Whether to disable inter-process locks'),
     cfg.StrOpt('lock_path',
+               default=os.environ.get("TEMPEST_LOCK_PATH"),
                help=('Directory to use for lock files.'))
 ]
 
@@ -131,6 +136,7 @@
     InterProcessLock = _PosixLock
 
 _semaphores = weakref.WeakValueDictionary()
+_semaphores_lock = threading.Lock()
 
 
 @contextlib.contextmanager
@@ -153,15 +159,12 @@
     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})
@@ -276,3 +279,27 @@
     """
 
     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["TEMPEST_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))