lockutils: improve the external locks test

Use a separate directory for the lockutils external locks and for the
test's flocks which are used to check that serialization is actually
occurring. By using the same directory, we can't test the code in
lockutils which auto-creates this directory because the dir gets
deleted by a process by lockutils cleanup while another directory
is using it for flocks.

Also, assume the the handles directory has been created in the parent
rather than having each child attempt to create it.

Related, add a try/finally block so that when a child process throws an
exception it immediately exits rather than deleting the temporary
directories created by the parent.

Change-Id: I32d7e8e05fb3f22cf38fa586f8bc97646c83f182

1 files changed, 13 insertions, 11 deletions

diff --git a/tests/unit/test_lockutils.py b/tests/unit/test_lockutils.py
index 685b0b8..e1f0375 100644
--- a/tests/unit/test_lockutils.py
+++ b/tests/unit/test_lockutils.py
@@ -127,18 +127,15 @@ class LockTestCase(utils.BaseTestCase):
 
     def test_synchronized_externally(self):
         """We can lock across multiple processes"""
-        tempdir = tempfile.mkdtemp()
-        self.config(lock_path=tempdir)
+        lock_dir = tempfile.mkdtemp()
+        self.config(lock_path=lock_dir)
 
         @lockutils.synchronized('external', 'test-', external=True)
-        def lock_files(tempdir):
-            if not os.path.exists(tempdir):
-                os.makedirs(tempdir)
-
+        def lock_files(handles_dir):
             # Open some files we can use for locking
             handles = []
             for n in range(50):
-                path = os.path.join(tempdir, ('file-%s' % n))
+                path = os.path.join(handles_dir, ('file-%s' % n))
                 handles.append(open(path, 'w'))
 
             # Loop over all the handles and try locking the file
@@ -159,6 +156,7 @@ class LockTestCase(utils.BaseTestCase):
             # Check if we were able to open all files
             self.assertEqual(50, count)
 
+        handles_dir = tempfile.mkdtemp()
         try:
             children = []
             for n in range(50):
@@ -166,13 +164,17 @@ class LockTestCase(utils.BaseTestCase):
                 if pid:
                     children.append(pid)
                 else:
-                    lock_files(tempdir)
-                    os._exit(0)
+                    try:
+                        lock_files(handles_dir)
+                    finally:
+                        os._exit(0)
 
             for i, child in enumerate(children):
                 (pid, status) = os.waitpid(child, 0)
                 if pid:
                     self.assertEqual(0, status)
         finally:
-            if os.path.exists(tempdir):
-                shutil.rmtree(tempdir, ignore_errors=True)
+            if os.path.exists(handles_dir):
+                shutil.rmtree(handles_dir, ignore_errors=True)
+            if os.path.exists(lock_dir):
+                shutil.rmtree(lock_dir, ignore_errors=True)