Add the missing locked() interface

threading.Lock has a little known locked() method, documented in
https://docs.python.org/2.6/library/thread.html#thread.lock.locked

This method is not very useful, but since pthreading.Lock must be
drop-in replacement for threading.Lock, we must implement it.

This patch adds the missing method, implementing it in the same way
Python implements it.  Since RLock does not have this method, RLock does
not extend Lock now.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>

pthreading.py

@@ -51,9 +51,9 @@
 import pthread
 
 
-class Lock(pthread.Mutex):
+class _Lock(pthread.Mutex):
     """
-    Lock class mimics Python native threading.Lock() API on top of
+    _Lock class mimics Python native threading.Lock() API on top of
     the POSIX thread mutex synchronization primitive.
     """
     def __enter__(self):
@@ -78,9 +78,19 @@ def release(self):
         self.unlock()
 
 
+class Lock(_Lock):
+    def locked(self):
+        # Yes, this is horrible hack, and the same one used by Python
+        # threadmodule.c. But this is part of Python lock interface.
+        if self.acquire(blocking=False):
+            self.release()
+            return False
+        return True
+
+
 class RLock(Lock):
     def __init__(self):
-        pthread.Mutex.__init__(self, recursive=True)
+        _Lock.__init__(self, recursive=True)
 
 
 class Condition(object):

tests.py

@@ -60,6 +60,13 @@ def testAcquireRecursive(self):
         self.assertTrue(lock.acquire())
         self.assertTrue(lock.acquire(False))
 
+    def testLocked(self):
+        lock = pthreading.Lock()
+        self.assertFalse(lock.locked())
+        with lock:
+            self.assertTrue(lock.locked())
+        self.assertFalse(lock.locked())
+
 
 class Flag(object):
     def __init__(self):