Merge pull request #293 from harlowja/no-more-re-entrant-lock

Have the lock recipe no longer be sorta re-entrant

CHANGES.rst

@@ -23,6 +23,13 @@ Features
 Bug Handling
 ************
 
+- #291: Kazoo lock recipe was only partially re-entrant in that multiple
+  calls to `acquire` would obtain the the lock but the first call to `release`
+  would remove the underlying lock. This would leave the X - 1 other `acquire`
+  statements unprotected (and no longer holding there expected lock). To fix
+  this the comment about that lock recipe being re-entrant has been removed
+  and multiple acquires will now raise a ``RuntimeError`` when attempted.
+
 - #78: Kazoo now uses socketpairs instead of pipes making it compatible with
   Windows.
 

kazoo/recipe/lock.py

@@ -40,8 +40,8 @@ class Lock(object):
         with lock:  # blocks waiting for lock acquisition
             # do something with the lock
 
-    Note: This lock is re-entrant. Repeat calls after acquired will
-    continue to return ''True''.
+    Note: This lock is not *re-entrant*. Repeated calls after already
+    acquired will raise a ``RuntimeError``.
 
     """
     _NODE_NAME = '__lock__'
@@ -106,6 +106,9 @@ def acquire(self, blocking=True, timeout=None):
         .. versionadded:: 1.1
             The timeout option.
         """
+        if self.is_acquired:
+            raise RuntimeError("Lock at path '%s' has already been"
+                               " acquired" % self.path)
         try:
             retry = self._retry.copy()
             retry.deadline = timeout

kazoo/tests/test_lock.py

@@ -240,12 +240,14 @@ def test_lock_cancel(self):
         thread1.join()
         client2.stop()
 
-    def test_lock_double_calls(self):
+    def test_lock_no_double_calls(self):
         lock1 = self.client.Lock(self.lockpath, "one")
         lock1.acquire()
-        lock1.acquire()
-        lock1.release()
+        self.assertTrue(lock1.is_acquired)
+        self.assertRaises(RuntimeError, lock1.acquire)
+        self.assertTrue(lock1.is_acquired)
         lock1.release()
+        self.assertFalse(lock1.is_acquired)
 
     def test_lock_reacquire(self):
         lock = self.client.Lock(self.lockpath, "one")