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-rw-r--r--sleekxmpp/xmlstream/statemachine.py20
1 files changed, 12 insertions, 8 deletions
diff --git a/sleekxmpp/xmlstream/statemachine.py b/sleekxmpp/xmlstream/statemachine.py
index dc54bb88..fab38dc3 100644
--- a/sleekxmpp/xmlstream/statemachine.py
+++ b/sleekxmpp/xmlstream/statemachine.py
@@ -91,7 +91,6 @@ class StateMachine(object):
else: return False
try: # lock is acquired; all other threads will return false or wait until notify/timeout
- self.notifier.clear()
if self.__current_state in from_states: # should always be True due to lock
# Note that func might throw an exception, but that's OK, it aborts the transition
@@ -108,7 +107,8 @@ class StateMachine(object):
log.error( "StateMachine bug!! The lock should ensure this doesn't happen!" )
return False
finally:
- self.notifier.set()
+ self.notifier.set() # notify any waiting threads that the state has changed.
+ self.notifier.clear()
self.lock.release()
@@ -154,7 +154,7 @@ class StateMachine(object):
return self.ensure_any( (state,), wait=wait )
- def ensure_any(self, states, wait=0.0):
+ def ensure_any(self, states, wait=0.0, block_on_transition=False):
'''
Ensure we are currently in one of the given `states` or wait until
we enter one of those states.
@@ -173,11 +173,15 @@ class StateMachine(object):
if not state in self.__states:
raise ValueError( "StateMachine does not contain state '%s'" % state )
- # Locking never really gained us anything here, since the lock was released
- # before the function returned anyways. The only thing it _did_ do was
- # increase the probability that this function would block for longer than
- # intended if a `transition` function or context was running while holding
- # the lock.
+ # if we're in the middle of a transition, determine whether we should
+ # 'fall back' to the 'current' state, or wait for the new state, in order to
+ # avoid an operation occurring in the wrong state.
+ # TODO another option would be an ensure_ctx that uses a semaphore to allow
+ # threads to indicate they want to remain in a particular state.
+
+ # will return immediately if no transition is in process.
+ if block_on_transition: self.notifier.wait()
+
start = time.time()
while not self.__current_state in states:
# detect timeout: