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path: root/sleekxmpp/xmlstream/statemachine.py
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Diffstat (limited to 'sleekxmpp/xmlstream/statemachine.py')
-rw-r--r--sleekxmpp/xmlstream/statemachine.py115
1 files changed, 96 insertions, 19 deletions
diff --git a/sleekxmpp/xmlstream/statemachine.py b/sleekxmpp/xmlstream/statemachine.py
index 0c841a9f..67b514a2 100644
--- a/sleekxmpp/xmlstream/statemachine.py
+++ b/sleekxmpp/xmlstream/statemachine.py
@@ -63,20 +63,22 @@ class StateMachine(object):
return self.transition_any( (from_state,), to_state, wait=wait,
func=func, args=args, kwargs=kwargs )
+
def transition_any(self, from_states, to_state, wait=0.0, func=None, args=[], kwargs={} ):
'''
Transition from any of the given `from_states` to the given `to_state`.
'''
- with self.lock:
- for state in from_states:
- if isinstance(state,tuple) or isinstance(state,list):
- raise ValueError( "State %s should be a string. Did you mean to call 'StateMachine.transition_any()?" % str(state) )
- if not state in self.__states:
- raise ValueError( "StateMachine does not contain from_state %s." % state )
- if not to_state in self.__states:
- raise ValueError( "StateMachine does not contain to_state %s." % to_state )
+ if not (isinstance(from_states,tuple) or isinstance(from_states,list)):
+ raise ValueError( "from_states should be a list or tuple" )
+ for state in from_states:
+ if not state in self.__states:
+ raise ValueError( "StateMachine does not contain from_state %s." % state )
+ if not to_state in self.__states:
+ raise ValueError( "StateMachine does not contain to_state %s." % to_state )
+
+ with self.lock:
start = time.time()
while not self.__current_state in from_states:
# detect timeout:
@@ -95,30 +97,67 @@ class StateMachine(object):
logging.debug(' ==== TRANSITION %s -> %s', self.__current_state, to_state)
self.__current_state = to_state
- self.lock.notifyAll()
+ self.lock.notify_all()
return return_val # some 'true' value returned by func or True if func was None
else:
logging.error( "StateMachine bug!! The lock should ensure this doesn't happen!" )
return False
+ def transition_ctx(self, from_state, to_state, wait=0.0):
+ '''
+ Use the state machine as a context manager. The transition occurs on /exit/ from
+ the `with` context, so long as no exception is thrown. For example:
+
+ ::
+
+ with state_machine.transition_ctx('one','two', wait=5) as locked:
+ if locked:
+ # the state machine is currently locked in state 'one', and will
+ # transition to 'two' when the 'with' statement ends, so long as
+ # no exception is thrown.
+ print 'Currently locked in state one: %s' % state_machine['one']
+
+ else:
+ # The 'wait' timed out, and no lock has been acquired
+ print 'Timed out before entering state "one"'
+
+ print 'Since no exception was thrown, we are now in state "two": %s' % state_machine['two']
+
+
+ The other main difference between this method and `transition()` is that the
+ state machine is locked for the duration of the `with` statement. Normally,
+ after a `transition()` occurs, the state machine is immediately unlocked and
+ available to another thread to call `transition()` again.
+ '''
+
+ if not from_state in self.__states:
+ raise ValueError( "StateMachine does not contain from_state %s." % from_state )
+ if not to_state in self.__states:
+ raise ValueError( "StateMachine does not contain to_state %s." % to_state )
+
+ return _StateCtx(self, from_state, to_state, wait)
+
+
def ensure(self, state, wait=0.0):
'''
Ensure the state machine is currently in `state`, or wait until it enters `state`.
'''
return self.ensure_any( (state,), wait=wait )
+
def ensure_any(self, states, wait=0.0):
'''
Ensure we are currently in one of the given `states`
'''
- with self.lock:
- for state in states:
- if isinstance(state,tuple) or isinstance(state,list):
- raise ValueError( "State %s should be a string. Did you mean to call 'StateMachine.transition_any()?" % str(state) )
- if not state in self.__states:
- raise ValueError( "StateMachine does not contain state %s." % state )
+ if not (isinstance(states,tuple) or isinstance(states,list)):
+ raise ValueError('states arg should be a tuple or list')
+ for state in states:
+ if not state in self.__states:
+ raise ValueError( "StateMachine does not contain state '%s'" % state )
+
+ with self.lock:
start = time.time()
while not self.__current_state in states:
# detect timeout:
@@ -132,6 +171,11 @@ class StateMachine(object):
self.transition(self.__current_state, self._default_state)
+ def _set_state(self, state): #unsynchronized, only call internally after lock is acquired
+ self.__current_state = state
+ return state
+
+
def current_state(self):
'''
Return the current state name.
@@ -145,13 +189,46 @@ class StateMachine(object):
Use `StateMachine.ensure(state)` to wait until the machine enters a certain state.
'''
return self.__current_state == state
+
+ def __str__(self):
+ return "".join(( "StateMachine(", ','.join(self.__states), "): ", self.__current_state ))
+
+
+class _StateCtx:
+
+ def __init__( self, state_machine, from_state, to_state, wait ):
+ self.state_machine = state_machine
+ self.from_state = from_state
+ self.to_state = to_state
+ self.wait = wait
+ self._timeout = False
+
def __enter__(self):
- self.lock.acquire()
- return self
+ self.state_machine.lock.acquire()
+ start = time.time()
+ while not self.state_machine[ self.from_state ]:
+ # detect timeout:
+ if time.time() >= start + self.wait:
+ logging.debug('StateMachine timeout while waiting for state: %s', self.from_state )
+ self._timeout = True # to indicate we should not transition
+ return False
+ self.state_machine.lock.wait(self.wait)
+
+ logging.debug('StateMachine entered context in state: %s',
+ self.state_machine.current_state() )
+ return True
def __exit__(self, exc_type, exc_val, exc_tb):
- self.lock.nofityAll()
- self.lock.release()
+ if exc_val is not None:
+ logging.exception( "StateMachine exception in context, remaining in state: %s\n%s:%s",
+ self.state_machine.current_state(), exc_type.__name__, exc_val )
+ elif not self._timeout:
+ logging.debug(' ==== TRANSITION %s -> %s',
+ self.state_machine.current_state(), self.to_state)
+ self.state_machine._set_state( self.to_state )
+
+ self.state_machine.lock.notify_all()
+ self.state_machine.lock.release()
return False # re-raise any exception