Implement context manager protocol for logging mutexes

Newer versions of python expect to be able to say `with self.lock:`
down in logging.

See https://github.com/python/cpython/commit/74723e11

Change-Id: I30305566d12a1b8be4c8bde4b416b798322a1385

swift/common/utils/logs.py

@@ -187,6 +187,13 @@ class PipeMutex(object):
         # do, so nobody does it and that's okay.
         self.close()
 
+    def __enter__(self):
+        self.acquire()
+        return self
+
+    def __exit__(self, *args):
+        self.release()
+
 
 class NoopMutex(object):
     """
@@ -219,6 +226,12 @@ class NoopMutex(object):
     def release(self):
         pass
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        pass
+
 
 class ThreadSafeSysLogHandler(SysLogHandler):
     def createLock(self):

test/unit/common/test_utils.py

@@ -5733,6 +5733,15 @@ class TestPipeMutex(unittest.TestCase):
         self.mutex.release()
         self.assertTrue(eventlet.spawn(try_acquire_lock).wait())
 
+    def test_context_manager_api(self):
+        def try_acquire_lock():
+            return self.mutex.acquire(blocking=False)
+
+        with self.mutex as ref:
+            self.assertIs(ref, self.mutex)
+            self.assertFalse(eventlet.spawn(try_acquire_lock).wait())
+        self.assertTrue(eventlet.spawn(try_acquire_lock).wait())
+
     def test_release_without_acquire(self):
         self.assertRaises(RuntimeError, self.mutex.release)
 
@@ -5867,6 +5876,24 @@ class TestPipeMutex(unittest.TestCase):
         eventlet.debug.hub_prevent_multiple_readers(True)
 
 
+class TestNoopMutex(unittest.TestCase):
+    def setUp(self):
+        self.mutex = utils.NoopMutex()
+
+    def test_acquire_release_api(self):
+        # Prior to 3.13, logging called these explicitly
+        self.mutex.acquire()
+        self.mutex.release()
+
+    def test_context_manager_api(self):
+        # python 3.13 started using it as a context manager
+        def try_acquire_lock():
+            return self.mutex.acquire(blocking=False)
+
+        with self.mutex as ref:
+            self.assertIs(ref, self.mutex)
+
+
 class TestDistributeEvenly(unittest.TestCase):
     def test_evenly_divided(self):
         out = utils.distribute_evenly(range(12), 3)