diff options
Diffstat (limited to 'sleekxmpp/xmlstream/statemachine.py')
| -rw-r--r-- | sleekxmpp/xmlstream/statemachine.py | 115 |
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 |