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authorThom Nichols <tmnichols@gmail.com>2010-06-02 12:39:54 -0400
committerThom Nichols <tmnichols@gmail.com>2010-06-02 12:39:54 -0400
commit7930ed22f2371ba3405f9644f427bec9554d2a15 (patch)
tree4eed9803932e32dd6e691b9dc2c6dc8b081dbb01 /sleekxmpp/xmlstream/statemachine.py
parent4eb210bff5753143300e5bf6ae09617901e9a28e (diff)
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overhauled state machine. Now allows for atomic transitions.
Next step: atomic function calls (and maybe 'handlers') on state transition.
Diffstat (limited to 'sleekxmpp/xmlstream/statemachine.py')
-rw-r--r--sleekxmpp/xmlstream/statemachine.py139
1 files changed, 105 insertions, 34 deletions
diff --git a/sleekxmpp/xmlstream/statemachine.py b/sleekxmpp/xmlstream/statemachine.py
index fb7d1508..c5f51765 100644
--- a/sleekxmpp/xmlstream/statemachine.py
+++ b/sleekxmpp/xmlstream/statemachine.py
@@ -7,53 +7,124 @@
"""
from __future__ import with_statement
import threading
+import time
+import logging
class StateMachine(object):
- def __init__(self, states=[], groups=[]):
- self.lock = threading.Lock()
- self.__state = {}
- self.__default_state = {}
- self.__group = {}
+ def __init__(self, states=[]):
+ self.lock = threading.Condition(threading.RLock())
+ self.__states= []
self.addStates(states)
- self.addGroups(groups)
+ self.__default_state = self.__states[0]
+ self.__current_state = self.__default_state
def addStates(self, states):
with self.lock:
for state in states:
- if state in self.__state or state in self.__group:
- raise IndexError("The state or group '%s' is already in the StateMachine." % state)
- self.__state[state] = states[state]
- self.__default_state[state] = states[state]
+ if state in self.__states:
+ raise IndexError("The state '%s' is already in the StateMachine." % state)
+ self.__states.append( state )
- def addGroups(self, groups):
- with self.lock:
- for gstate in groups:
- if gstate in self.__state or gstate in self.__group:
- raise IndexError("The key or group '%s' is already in the StateMachine." % gstate)
- for state in groups[gstate]:
- if state in self.__state:
- raise IndexError("The group %s contains a key %s which is not set in the StateMachine." % (gstate, state))
- self.__group[gstate] = groups[gstate]
- def set(self, state, status):
+ def transition(self, from_state, to_state, wait=0.0):
+ '''
+ Transition from the given `from_state` to the given `to_state`.
+ This method will return `True` if the state machine is now in `to_state`. It
+ will return `False` if a timeout occurred the transition did not occur.
+ If `wait` is 0 (the default,) this method returns immediately if the state machine
+ is not in `from_state`.
+
+ If you want the thread to block and transition once the state machine to enters
+ `from_state`, set `wait` to a non-negative value. Note there is no 'block
+ indefinitely' flag since this leads to deadlock. If you want to wait indefinitely,
+ choose a reasonable value for `wait` (e.g. 20 seconds) and do so in a while loop like so:
+
+ ::
+
+ while not thread_should_exit and not state_machine.transition('disconnected', 'connecting', wait=20 ):
+ pass # timeout will occur every 20s unless transition occurs
+ if thread_should_exit: return
+ # perform actions here after successful transition
+
+ This allows the thread to be interrupted by setting `thread_should_exit=True`
+ '''
+
+ return self.transition_any( (from_state,), to_state, wait=wait )
+
+ def transition_any(self, from_states, to_state, wait=0.0):
+ '''
+ Transition from any of the given `from_states` to the given `to_state`.
+ '''
+
with self.lock:
- if state in self.__state:
- self.__state[state] = bool(status)
+ 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 )
+
+ start = time.time()
+ while not self.__current_state in from_states:
+ # detect timeout:
+ if time.time() >= start + wait: return False
+ self.lock.wait(wait)
+
+ if self.__current_state in from_states: # should always be True due to lock
+ logging.debug(' ==== TRANSITION %s -> %s', self.__current_state, to_state)
+ self.__current_state = to_state
+ self.lock.notifyAll()
+ return True
else:
- raise KeyError("StateMachine does not contain state %s." % state)
+ logging.error( "StateMachine bug!! The lock should ensure this doesn't happen!" )
+ return False
+
+
+ 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 )
+
+ start = time.time()
+ while not self.__current_state in states:
+ # detect timeout:
+ if time.time() >= start + wait: return False
+ self.lock.wait(wait)
+ return self.__current_state in states # should always be True due to lock
+
- def __getitem__(self, key):
- if key in self.__group:
- for state in self.__group[key]:
- if not self.__state[state]:
- return False
- return True
- return self.__state[key]
+ def reset(self):
+ # TODO need to lock before calling this?
+ self.transition(self.__current_state, self._default_state)
- def __getattr__(self, attr):
- return self.__getitem__(attr)
+
+ def __getitem__(self, state):
+ '''
+ Non-blocking, non-synchronized test to determine if we are in the given state.
+ Use `StateMachine.ensure(state)` to wait until the machine enters a certain state.
+ '''
+ return self.__current_state == state
- def reset(self):
- self.__state = self.__default_state
+ def __enter__(self):
+ self.lock.acquire()
+ return self
+
+ def __exit__(self, exc_type, exc_val, exc_tb):
+ self.lock.nofityAll()
+ self.lock.release()
+ return False # re-raise any exception