openstack/automaton
Code Issues Proposed changes

Split the state machine runners off into own file

Browse Source 
When using a state machine it is not always desired
to use the runner concept, so to ensure both concepts
are modular split runners off into there own module.

Change-Id: Iac8ce50b0a17468190f3f737663b5b094c324a55
This commit is contained in:
Joshua Harlow 2015-06-05 17:06:25 -07:00
parent 33c7e82b94
commit bcb61f0b0d
4 changed files with 188 additions and 153 deletions

140
automaton/machines.py

@ -20,7 +20,6 @@ except ImportError:
from ordereddict import OrderedDict # noqa
import collections
import weakref
from debtcollector import removals
import prettytable
@ -28,11 +27,6 @@ import six
from automaton import exceptions as excp
_JUMPER_NOT_FOUND_TPL = ("Unable to progress since no reaction (or"
" sent event) has been made available in"
" new state '%s' (moved to from state '%s'"
" in response to event '%s')")
def _orderedkeys(data, sort=True):
if sort:
@ -90,13 +84,8 @@ class FiniteMachine(object):
self._states = OrderedDict()
self._default_start_state = default_start_state
self._current = None
self._runner = _FiniteRunner(self)
self.frozen = False
@property
def runner(self):
return self._runner
@property
def default_start_state(self):
return self._default_start_state
@ -356,48 +345,6 @@ class FiniteMachine(object):
return tbl.get_string()
class _FiniteRunner(object):
"""Finite machine runner used to run a finite machine."""
def __init__(self, machine):
self._machine = weakref.proxy(machine)
def run(self, event, initialize=True):
"""Runs the state machine, using reactions only."""
for transition in self.run_iter(event, initialize=initialize):
pass
def run_iter(self, event, initialize=True):
"""Returns a iterator/generator that will run the state machine.
NOTE(harlowja): only one runner iterator/generator should be active for
a machine, if this is not observed then it is possible for
initialization and other local state to be corrupted and cause issues
when running...
"""
if initialize:
self._machine.initialize()
while True:
old_state = self._machine.current_state
reaction, terminal = self._machine.process_event(event)
new_state = self._machine.current_state
try:
sent_event = yield (old_state, new_state)
except GeneratorExit:
break
if terminal:
break
if reaction is None and sent_event is None:
raise excp.NotFound(_JUMPER_NOT_FOUND_TPL % (new_state,
old_state,
event))
elif sent_event is not None:
event = sent_event
else:
cb, args, kwargs = reaction
event = cb(old_state, new_state, event, *args, **kwargs)
class HierarchicalFiniteMachine(FiniteMachine):
"""A fsm that understands how to run in a hierarchical mode."""
@ -408,7 +355,6 @@ class HierarchicalFiniteMachine(FiniteMachine):
def __init__(self, default_start_state=None):
super(HierarchicalFiniteMachine, self).__init__(
default_start_state=default_start_state)
self._runner = _HierarchicalRunner(self)
self._nested_machines = {}
@classmethod
@ -446,89 +392,3 @@ class HierarchicalFiniteMachine(FiniteMachine):
@property
def nested_machines(self):
return self._nested_machines
class _HierarchicalRunner(object):
"""Hierarchical machine runner used to run a hierarchical machine."""
def __init__(self, machine):
self._machine = weakref.proxy(machine)
def run(self, event, initialize=True):
"""Runs the state machine, using reactions only."""
for transition in self.run_iter(event, initialize=initialize):
pass
@staticmethod
def _process_event(machines, event):
"""Matches a event to the machine hierarchy.
If the lowest level machine does not handle the event, then the
parent machine is referred to and so on, until there is only one
machine left which *must* handle the event.
The machine whose ``process_event`` does not throw invalid state or
not found exceptions is expected to be the machine that should
continue handling events...
"""
while True:
machine = machines[-1]
try:
result = machine.process_event(event)
except (excp.InvalidState, excp.NotFound):
if len(machines) == 1:
raise
else:
current = machine._current
if current is not None and current.on_exit is not None:
current.on_exit(current.name, event)
machine._current = None
machines.pop()
else:
return result
def run_iter(self, event, initialize=True):
"""Returns a iterator/generator that will run the state machine.
This will keep a stack (hierarchy) of machines active and jumps through
them as needed (depending on which machine handles which event) during
the running lifecycle.
NOTE(harlowja): only one runner iterator/generator should be active for
a machine hierarchy, if this is not observed then it is possible for
initialization and other local state to be corrupted and causes issues
when running...
"""
machines = [self._machine]
if initialize:
machines[-1].initialize()
while True:
old_state = machines[-1].current_state
effect = self._process_event(machines, event)
new_state = machines[-1].current_state
try:
machine = effect.machine
except AttributeError:
pass
else:
if machine is not None and machine is not machines[-1]:
machine.initialize()
machines.append(machine)
try:
sent_event = yield (old_state, new_state)
except GeneratorExit:
break
if len(machines) == 1 and effect.terminal:
# Only allow the top level machine to actually terminate the
# execution, the rest of the nested machines must not handle
# events if they wish to have the root machine terminate...
break
if effect.reaction is None and sent_event is None:
raise excp.NotFound(_JUMPER_NOT_FOUND_TPL % (new_state,
old_state,
event))
elif sent_event is not None:
event = sent_event
else:
cb, args, kwargs = effect.reaction
event = cb(old_state, new_state, event, *args, **kwargs)

169
automaton/runners.py Normal file

@ -0,0 +1,169 @@
# -*- coding: utf-8 -*-
# Copyright (C) 2015 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from automaton import exceptions as excp
from automaton import machines
_JUMPER_NOT_FOUND_TPL = ("Unable to progress since no reaction (or"
" sent event) has been made available in"
" new state '%s' (moved to from state '%s'"
" in response to event '%s')")
class FiniteRunner(object):
"""Finite machine runner used to run a finite machine.
Only **one** runner per machine should be active at the same time (aka
there should not be multiple runners using the same machine instance at
the same time).
"""
def __init__(self, machine):
"""Create a runner for the given machine."""
if not isinstance(machine, (machines.FiniteMachine,)):
raise TypeError("FiniteRunner only works with FiniteMachine(s)")
self._machine = machine
def run(self, event, initialize=True):
"""Runs the state machine, using reactions only."""
for transition in self.run_iter(event, initialize=initialize):
pass
def run_iter(self, event, initialize=True):
"""Returns a iterator/generator that will run the state machine.
NOTE(harlowja): only one runner iterator/generator should be active for
a machine, if this is not observed then it is possible for
initialization and other local state to be corrupted and cause issues
when running...
"""
if initialize:
self._machine.initialize()
while True:
old_state = self._machine.current_state
reaction, terminal = self._machine.process_event(event)
new_state = self._machine.current_state
try:
sent_event = yield (old_state, new_state)
except GeneratorExit:
break
if terminal:
break
if reaction is None and sent_event is None:
raise excp.NotFound(_JUMPER_NOT_FOUND_TPL % (new_state,
old_state,
event))
elif sent_event is not None:
event = sent_event
else:
cb, args, kwargs = reaction
event = cb(old_state, new_state, event, *args, **kwargs)
class HierarchicalRunner(object):
"""Hierarchical machine runner used to run a hierarchical machine.
Only **one** runner per machine should be active at the same time (aka
there should not be multiple runners using the same machine instance at
the same time).
"""
def __init__(self, machine):
"""Create a runner for the given machine."""
if not isinstance(machine, (machines.HierarchicalFiniteMachine,)):
raise TypeError("HierarchicalRunner only works with"
" HierarchicalFiniteMachine(s)")
self._machine = machine
def run(self, event, initialize=True):
"""Runs the state machine, using reactions only."""
for transition in self.run_iter(event, initialize=initialize):
pass
@staticmethod
def _process_event(machines, event):
"""Matches a event to the machine hierarchy.
If the lowest level machine does not handle the event, then the
parent machine is referred to and so on, until there is only one
machine left which *must* handle the event.
The machine whose ``process_event`` does not throw invalid state or
not found exceptions is expected to be the machine that should
continue handling events...
"""
while True:
machine = machines[-1]
try:
result = machine.process_event(event)
except (excp.InvalidState, excp.NotFound):
if len(machines) == 1:
raise
else:
current = machine._current
if current is not None and current.on_exit is not None:
current.on_exit(current.name, event)
machine._current = None
machines.pop()
else:
return result
def run_iter(self, event, initialize=True):
"""Returns a iterator/generator that will run the state machine.
This will keep a stack (hierarchy) of machines active and jumps through
them as needed (depending on which machine handles which event) during
the running lifecycle.
NOTE(harlowja): only one runner iterator/generator should be active for
a machine hierarchy, if this is not observed then it is possible for
initialization and other local state to be corrupted and causes issues
when running...
"""
machines = [self._machine]
if initialize:
machines[-1].initialize()
while True:
old_state = machines[-1].current_state
effect = self._process_event(machines, event)
new_state = machines[-1].current_state
try:
machine = effect.machine
except AttributeError:
pass
else:
if machine is not None and machine is not machines[-1]:
machine.initialize()
machines.append(machine)
try:
sent_event = yield (old_state, new_state)
except GeneratorExit:
break
if len(machines) == 1 and effect.terminal:
# Only allow the top level machine to actually terminate the
# execution, the rest of the nested machines must not handle
# events if they wish to have the root machine terminate...
break
if effect.reaction is None and sent_event is None:
raise excp.NotFound(_JUMPER_NOT_FOUND_TPL % (new_state,
old_state,
event))
elif sent_event is not None:
event = sent_event
else:
cb, args, kwargs = effect.reaction
event = cb(old_state, new_state, event, *args, **kwargs)

28
automaton/tests/test_fsm.py

@ -19,6 +19,7 @@ import random
from automaton import exceptions as excp
from automaton import machines
from automaton import runners
import six
from testtools import testcase
@ -50,7 +51,8 @@ class FSMTest(testcase.TestCase):
def test_bad_start_state(self):
m = self._create_fsm('unknown', add_start=False)
self.assertRaises(excp.NotFound, m.runner.run, 'unknown')
r = runners.FiniteRunner(m)
self.assertRaises(excp.NotFound, r.run, 'unknown')
def test_contains(self):
m = self._create_fsm('unknown', add_start=False)
@ -92,11 +94,11 @@ class FSMTest(testcase.TestCase):
m.initialize()
self.assertEqual('down', m.current_state)
self.assertFalse(m.terminated)
m_runner = m.runner
m_runner.run('jump')
r = runners.FiniteRunner(m)
r.run('jump')
self.assertTrue(m.terminated)
self.assertEqual('broken', m.current_state)
self.assertRaises(excp.InvalidState, m_runner.run,
self.assertRaises(excp.InvalidState, r.run,
'jump', initialize=False)
def test_on_enter_on_exit(self):
@ -128,7 +130,7 @@ class FSMTest(testcase.TestCase):
def test_run_iter(self):
up_downs = []
runner = self.jumper.runner
runner = runners.FiniteRunner(self.jumper)
for (old_state, new_state) in runner.run_iter('jump'):
up_downs.append((old_state, new_state))
if len(up_downs) >= 3:
@ -142,7 +144,7 @@ class FSMTest(testcase.TestCase):
def test_run_send(self):
up_downs = []
runner = self.jumper.runner
runner = runners.FiniteRunner(self.jumper)
it = runner.run_iter('jump')
while True:
up_downs.append(it.send(None))
@ -157,7 +159,7 @@ class FSMTest(testcase.TestCase):
def test_run_send_fail(self):
up_downs = []
runner = self.jumper.runner
runner = runners.FiniteRunner(self.jumper)
it = runner.run_iter('jump')
up_downs.append(six.next(it))
self.assertRaises(excp.NotFound, it.send, 'fail')
@ -196,8 +198,9 @@ class FSMTest(testcase.TestCase):
def test_copy_initialized(self):
j = self.jumper.copy()
self.assertIsNone(j.current_state)
r = runners.FiniteRunner(self.jumper)
for i, transition in enumerate(self.jumper.runner.run_iter('jump')):
for i, transition in enumerate(r.run_iter('jump')):
if i == 4:
break
@ -317,7 +320,8 @@ class HFSMTest(FSMTest):
def test_phone_dialer_iter(self):
dialer, number_calling = self._make_phone_dialer()
self.assertEqual(0, len(number_calling))
transitions = list(dialer.runner.run_iter('dial'))
r = runners.HierarchicalRunner(dialer)
transitions = list(r.run_iter('dial'))
self.assertEqual(('talk', 'hangup'), transitions[-1])
self.assertEqual(len(number_calling),
sum(1 if new_state == 'accumulate' else 0
@ -326,12 +330,14 @@ class HFSMTest(FSMTest):
def test_phone_call(self):
handler = self._make_phone_call()
handler.runner.run('call')
r = runners.HierarchicalRunner(handler)
r.run('call')
self.assertTrue(handler.terminated)
def test_phone_call_iter(self):
handler = self._make_phone_call()
transitions = list(handler.runner.run_iter('call'))
r = runners.HierarchicalRunner(handler)
transitions = list(r.run_iter('call'))
self.assertEqual(('talk', 'hangup'), transitions[-1])
self.assertEqual(("begin", 'phone'), transitions[0])
talk_talk = 0

4
doc/source/api.rst

@ -16,10 +16,10 @@ Machines
Runners
-------
.. autoclass:: automaton.machines._FiniteRunner
.. autoclass:: automaton.runners.FiniteRunner
:members:
.. autoclass:: automaton.machines._HierarchicalRunner
.. autoclass:: automaton.runners.HierarchicalRunner
:members:
----------