class Foreach(FlowExpression):
"""Foreach activity."""
allowed_child_types = _get_supported_activities()
is_cond_allowed = True
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
FlowExpression.__init__(self, parent_id, element, fei, context)
# these are needed to reset local context upon every iteration
self._parent_ctx = context
self._element = element
def _activate(self, msg):
if self._is_start_message(msg):
selection = self._parent_ctx
for key in self._element.attrib["select"].split('.'):
selection = selection.get(key)
assert isinstance(selection, list), "%s is not list" % selection
self.context.set('inst:selection', selection)
self.context.set('inst:iteration', 1)
if len(selection) > 0:
self.context.set('inst:current', selection[0])
def handle_message(self, channel, msg):
"""Handle message."""
def guard():
selection_size = len(self.context.get('inst:selection'))
if self.context.get('inst:iteration') < selection_size:
return True
else:
return False
def restart():
iteration = self.context.get('inst:iteration')
selection = self.context.get('inst:selection')
self.context = Context(self._parent_ctx)
for child in self._element:
if child.tag == 'context':
self.context.parse(child)
break
self.reset_children()
self.context.set('inst:iteration', iteration + 1)
self.context.set('inst:current', selection[iteration])
self.context.set('inst:selection', selection)
channel.send(
Message(name='start',
target=self.children[0].id,
origin=self.id))
return FlowExpression.handle_message(self, channel, msg) or \
self._activate(msg) or \
self._was_activated(channel, msg, guard) or \
self._was_sequence_completed(channel, msg,
lambda: not guard(),
restart) or \
self._was_consumed_by_child(channel, msg) or 'ignored'
class Foreach(FlowExpression):
"""Foreach activity."""
allowed_child_types = _get_supported_activities()
is_cond_allowed = True
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
FlowExpression.__init__(self, parent_id, element, fei, context)
# these are needed to reset local context upon every iteration
self._parent_ctx = context
self._element = element
def _activate(self, msg):
if self._is_start_message(msg):
selection = self._parent_ctx
for key in self._element.attrib["select"].split('.'):
selection = selection.get(key)
assert isinstance(selection, list), "%s is not list" % selection
self.context.set('inst:selection', selection)
self.context.set('inst:iteration', 1)
if len(selection) > 0:
self.context.set('inst:current', selection[0])
def handle_message(self, channel, msg):
"""Handle message."""
def guard():
selection_size = len(self.context.get('inst:selection'))
if self.context.get('inst:iteration') < selection_size:
return True
else:
return False
def restart():
iteration = self.context.get('inst:iteration')
selection = self.context.get('inst:selection')
self.context = Context(self._parent_ctx)
for child in self._element:
if child.tag == 'context':
self.context.parse(child)
break
self.reset_children()
self.context.set('inst:iteration', iteration + 1)
self.context.set('inst:current', selection[iteration])
self.context.set('inst:selection', selection)
channel.send(Message(name='start', target=self.children[0].id,
origin=self.id))
return FlowExpression.handle_message(self, channel, msg) or \
self._activate(msg) or \
self._was_activated(channel, msg, guard) or \
self._was_sequence_completed(channel, msg,
lambda: not guard(),
restart) or \
self._was_consumed_by_child(channel, msg) or 'ignored'
class While(FlowExpression):
"""While activity."""
allowed_child_types = _get_supported_activities()
is_cond_allowed = True
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
self.conditions = []
FlowExpression.__init__(self, parent_id, element, fei, context)
# these are needed to reset local context upon every iteration
self._parent_ctx = context
self._element = element
def evaluate(self):
"""Check if conditions are met."""
for cond in self.conditions:
if eval(cond, {"context": self.context.as_dictionary()}):
LOG.debug("Condition %s evaluated to True", cond)
return True
else:
LOG.debug("Condition %s evaluated to False", cond)
return False
def handle_message(self, channel, msg):
"""Handle message."""
def restart():
self.context = Context(self._parent_ctx)
for child in self._element:
if child.tag == 'context':
self.context.parse(child)
break
self.reset_children()
channel.send(
Message(name='start',
target=self.children[0].id,
origin=self.id))
return FlowExpression.handle_message(self, channel, msg) or \
self._was_activated(channel, msg, self.evaluate) or \
self._was_sequence_completed(channel, msg,
lambda: not self.evaluate(),
restart) or \
self._was_consumed_by_child(channel, msg) or 'ignored'
class While(FlowExpression):
"""While activity."""
allowed_child_types = _get_supported_activities()
is_cond_allowed = True
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
self.conditions = []
FlowExpression.__init__(self, parent_id, element, fei, context)
# these are needed to reset local context upon every iteration
self._parent_ctx = context
self._element = element
def evaluate(self):
"""Check if conditions are met."""
for cond in self.conditions:
if eval(cond, {"context": self.context.as_dictionary()}):
LOG.debug("Condition %s evaluated to True", cond)
return True
else:
LOG.debug("Condition %s evaluated to False", cond)
return False
def handle_message(self, channel, msg):
"""Handle message."""
def restart():
self.context = Context(self._parent_ctx)
for child in self._element:
if child.tag == 'context':
self.context.parse(child)
break
self.reset_children()
channel.send(Message(name='start', target=self.children[0].id,
origin=self.id))
return FlowExpression.handle_message(self, channel, msg) or \
self._was_activated(channel, msg, self.evaluate) or \
self._was_sequence_completed(channel, msg,
lambda: not self.evaluate(),
restart) or \
self._was_consumed_by_child(channel, msg) or 'ignored'
class FlowExpression(object):
"""Flow expression."""
allowed_child_types = ()
is_ctx_allowed = True # TODO: refactor to introduce simple and complex activities
is_cond_allowed = False
is_handler = False
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
self.fe_name = self.__class__.__name__.lower()
LOG.debug("Creating %s", self.fe_name)
self.state = 'ready'
self.id = fei
self.parent_id = parent_id
self.children = []
self.faults = None
if self.is_ctx_allowed:
self.context = Context(context)
else:
self.context = context
el_index = 0
for child in element:
if child.tag in self.allowed_child_types:
fexpr = _create_fe_from_element(self.id, child,
"%s_%d" % (fei, el_index),
self.context)
self.children.append(fexpr)
el_index = el_index + 1
else:
self._parse_non_child(child)
def __str__(self):
"""String representation."""
return "%s" % self.id
def __repr__(self):
"""Instance representation."""
return "<%s[%s, state='%s']>" % (self.__class__.__name__, self,
self.state)
def _parse_non_child(self, element):
"""Parse disallowed child element.
Some flow expressions can contain child elements in their definition
which are just attributes of them, not other flow expression.
As an example consider <condition> inside <case>.
"""
if element.tag == 'context' and self.is_ctx_allowed:
self.context.parse(element)
for child in element:
if child.tag == 'faults':
self.faults = Faults(self.id, child, "%s_faults" % self.id,
self.context)
break
elif element.tag == 'condition' and self.is_cond_allowed:
html_parser = HTMLParser()
self.conditions.append(html_parser.unescape(element.text))
else:
raise FlowExpressionError("'%s' is disallowed child type" % \
element.tag)
def snapshot(self):
"""Return flow expression snapshot."""
snapshot = {
"id": self.id,
"state": self.state,
"type": self.fe_name,
"children": [child.snapshot() for child in self.children]
}
if self.is_ctx_allowed:
snapshot["context"] = self.context.localprops
if self.faults:
snapshot["faults"] = self.faults.snapshot()
return snapshot
def reset_state(self, state):
"""Reset activity's state."""
LOG.debug("Resetting %s's state", self.fe_name)
assert state["type"] == self.fe_name
assert state["id"] == self.id
self.state = state["state"]
if self.is_ctx_allowed:
self.context.localprops = state["context"]
if self.faults:
self.faults.reset_state(state["faults"])
for child, childstate in zip(self.children, state["children"]):
child.reset_state(childstate)
def handle_message(self, channel, msg):
"""Handle message.
This is common code used by all derived classes.
"""
result = ''
if self.state == 'completed':
LOG.debug("%r is done already, %r is ignored", self, msg)
result = 'ignored'
elif msg.target is not None and \
not msg.target.startswith(self.id):
LOG.debug("%r is not for %r", msg, self)
result = 'ignored'
elif (self.is_ctx_allowed or self.is_handler) and \
self.state == 'active' and \
msg.name == 'fault' and msg.target == self.id:
self.state = 'aborting'
self.context.throw(code=msg.payload.get('code', 'GenericError'),
message=msg.payload.get('message', ''))
all_in_final_state = True
for child in self.children:
if not is_state_final(child.state):
all_in_final_state = False
channel.send(Message(name='terminate', target=child.id,
origin=self.id))
if all_in_final_state:
self.state = 'aborted'
channel.send(Message(name='fault', target=self.parent_id,
origin=self.id, payload=msg.payload))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'active' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborting'
for child in self.children:
if not is_state_final(child.state):
channel.send(Message(name='terminate', target=child.id,
origin=self.id))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'ready' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'canceling'
for child in self.children:
if not is_state_final(child.state):
channel.send(Message(name='terminate', target=child.id,
origin=self.id))
result = 'consumed'
elif (self.is_ctx_allowed or self.is_handler) and \
self.state == 'aborting' and \
(msg.name == 'canceled' or msg.name == 'aborted' or \
msg.name == 'completed') and \
msg.target == self.id:
if msg.name == 'completed' and msg.origin.endswith("faults"):
self.state = 'completed'
del self.context._props['inst:fault']
channel.send(Message(name='completed', target=self.parent_id,
origin=self.id))
elif sum([int(is_state_final(child.state))
for child in self.children]) == len(self.children):
# all children are in a final state
if self.faults and self.faults.state == 'ready':
channel.send(Message(name='start', target=self.faults.id,
origin=self.id))
else:
self.state = 'aborted'
channel.send(Message(name='fault', target=self.parent_id,
origin=self.id,
payload=self.context.get('inst:fault')))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'aborting' and \
msg.name == 'fault' and msg.target == self.id:
self.state = 'aborted'
channel.send(Message(name='fault', target=self.parent_id,
origin=self.id,
payload=self.context.get('inst:fault')))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'canceling' and \
(msg.name == 'canceled' or msg.name == 'aborted' or \
msg.name == 'completed') and msg.target == self.id:
if sum([int(is_state_final(child.state))
for child in self.children]) == len(self.children):
# all children are in a final state
channel.send(Message(name='canceled', target=self.parent_id,
origin=self.id))
self.state = 'canceled'
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'active' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborted'
channel.send(Message(name='aborted', target=self.parent_id,
origin=self.id))
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'ready' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'canceled'
channel.send(Message(name='canceled', target=self.parent_id,
origin=self.id))
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'aborting' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborted'
channel.send(Message(name='aborted', target=self.parent_id,
origin=self.id))
result = 'consumed'
return result
def _was_activated(self, channel, msg, guard=lambda: True):
"""Check if it's activation message."""
if self._is_start_message(msg):
if not guard():
LOG.debug("Conditions for %r don't hold", self)
self.state = 'completed'
channel.send(Message(name='completed', origin=self.id,
target=self.parent_id))
return 'consumed'
if len(self.children) > 0:
self.state = 'active'
channel.send(Message(name='start', origin=self.id,
target=self.children[0].id))
else:
self.state = 'completed'
channel.send(Message(name='completed', origin=self.id,
target=self.parent_id))
return 'consumed'
else:
return ''
def _was_sequence_completed(self, channel, msg, guard=lambda: True,
compensate=lambda: None):
"""Check if all children in sequence were completed."""
res = ''
if self._is_complete_message(msg):
for index, child in zip(range(0, len(self.children)),
self.children):
if child.id == msg.origin:
if (index + 1) < len(self.children):
channel.send(Message(name='start', origin=self.id,
target="%s_%d" % (self.id,
index + 1)))
else:
if guard():
self.state = 'completed'
channel.send(Message(name='completed',
origin=self.id,
target=self.parent_id))
else:
compensate()
res = 'consumed'
break
return res
def _was_consumed_by_child(self, channel, msg):
"""Check if a child consumed the message."""
for child in self.children:
if msg.target.startswith(child.id):
return child.handle_message(channel, msg)
if self.state == 'aborting' and self.faults and \
msg.target.startswith(self.faults.id):
return self.faults.handle_message(channel, msg)
def _is_start_message(self, msg):
"""Return True if the message destined to start the activity."""
return self.state == 'ready' and msg.name == 'start' \
and msg.target == self.id
def _is_complete_message(self, msg):
"""Return True if the message is from completed child."""
return self.state == 'active' and msg.name == 'completed' \
and msg.target == self.id
def reset_children(self):
"""Reset children state to ready."""
for child in self.children:
child.state = 'ready'
child.reset_children()
class FlowExpression(object):
"""Flow expression."""
allowed_child_types = ()
is_ctx_allowed = True # TODO: refactor to introduce simple and complex activities
is_cond_allowed = False
is_handler = False
def __init__(self, parent_id, element, fei, context):
"""Constructor."""
self.fe_name = self.__class__.__name__.lower()
LOG.debug("Creating %s", self.fe_name)
self.state = 'ready'
self.id = fei
self.parent_id = parent_id
self.children = []
self.faults = None
if self.is_ctx_allowed:
self.context = Context(context)
else:
self.context = context
el_index = 0
for child in element:
if child.tag in self.allowed_child_types:
fexpr = _create_fe_from_element(self.id, child,
"%s_%d" % (fei, el_index),
self.context)
self.children.append(fexpr)
el_index = el_index + 1
else:
self._parse_non_child(child)
def __str__(self):
"""String representation."""
return "%s" % self.id
def __repr__(self):
"""Instance representation."""
return "<%s[%s, state='%s']>" % (self.__class__.__name__, self,
self.state)
def _parse_non_child(self, element):
"""Parse disallowed child element.
Some flow expressions can contain child elements in their definition
which are just attributes of them, not other flow expression.
As an example consider <condition> inside <case>.
"""
if element.tag == 'context' and self.is_ctx_allowed:
self.context.parse(element)
for child in element:
if child.tag == 'faults':
self.faults = Faults(self.id, child, "%s_faults" % self.id,
self.context)
break
elif element.tag == 'condition' and self.is_cond_allowed:
html_parser = HTMLParser()
self.conditions.append(html_parser.unescape(element.text))
else:
raise FlowExpressionError("'%s' is disallowed child type" % \
element.tag)
def snapshot(self):
"""Return flow expression snapshot."""
snapshot = {
"id": self.id,
"state": self.state,
"type": self.fe_name,
"children": [child.snapshot() for child in self.children]
}
if self.is_ctx_allowed:
snapshot["context"] = self.context.localprops
if self.faults:
snapshot["faults"] = self.faults.snapshot()
return snapshot
def reset_state(self, state):
"""Reset activity's state."""
LOG.debug("Resetting %s's state", self.fe_name)
assert state["type"] == self.fe_name
assert state["id"] == self.id
self.state = state["state"]
if self.is_ctx_allowed:
self.context.localprops = state["context"]
if self.faults:
self.faults.reset_state(state["faults"])
for child, childstate in zip(self.children, state["children"]):
child.reset_state(childstate)
def handle_message(self, channel, msg):
"""Handle message.
This is common code used by all derived classes.
"""
result = ''
if self.state == 'completed':
LOG.debug("%r is done already, %r is ignored", self, msg)
result = 'ignored'
elif msg.target is not None and \
not msg.target.startswith(self.id):
LOG.debug("%r is not for %r", msg, self)
result = 'ignored'
elif (self.is_ctx_allowed or self.is_handler) and \
self.state == 'active' and \
msg.name == 'fault' and msg.target == self.id:
self.state = 'aborting'
self.context.throw(code=msg.payload.get('code', 'GenericError'),
message=msg.payload.get('message', ''))
all_in_final_state = True
for child in self.children:
if not is_state_final(child.state):
all_in_final_state = False
channel.send(
Message(name='terminate',
target=child.id,
origin=self.id))
if all_in_final_state:
self.state = 'aborted'
channel.send(
Message(name='fault',
target=self.parent_id,
origin=self.id,
payload=msg.payload))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'active' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborting'
for child in self.children:
if not is_state_final(child.state):
channel.send(
Message(name='terminate',
target=child.id,
origin=self.id))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'ready' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'canceling'
for child in self.children:
if not is_state_final(child.state):
channel.send(
Message(name='terminate',
target=child.id,
origin=self.id))
result = 'consumed'
elif (self.is_ctx_allowed or self.is_handler) and \
self.state == 'aborting' and \
(msg.name == 'canceled' or msg.name == 'aborted' or \
msg.name == 'completed') and \
msg.target == self.id:
if msg.name == 'completed' and msg.origin.endswith("faults"):
self.state = 'completed'
del self.context._props['inst:fault']
channel.send(
Message(name='completed',
target=self.parent_id,
origin=self.id))
elif sum([
int(is_state_final(child.state)) for child in self.children
]) == len(self.children):
# all children are in a final state
if self.faults and self.faults.state == 'ready':
channel.send(
Message(name='start',
target=self.faults.id,
origin=self.id))
else:
self.state = 'aborted'
channel.send(
Message(name='fault',
target=self.parent_id,
origin=self.id,
payload=self.context.get('inst:fault')))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'aborting' and \
msg.name == 'fault' and msg.target == self.id:
self.state = 'aborted'
channel.send(
Message(name='fault',
target=self.parent_id,
origin=self.id,
payload=self.context.get('inst:fault')))
result = 'consumed'
elif self.is_ctx_allowed and self.state == 'canceling' and \
(msg.name == 'canceled' or msg.name == 'aborted' or \
msg.name == 'completed') and msg.target == self.id:
if sum([
int(is_state_final(child.state)) for child in self.children
]) == len(self.children):
# all children are in a final state
channel.send(
Message(name='canceled',
target=self.parent_id,
origin=self.id))
self.state = 'canceled'
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'active' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborted'
channel.send(
Message(name='aborted', target=self.parent_id, origin=self.id))
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'ready' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'canceled'
channel.send(
Message(name='canceled', target=self.parent_id,
origin=self.id))
result = 'consumed'
elif not self.is_ctx_allowed and self.state == 'aborting' and \
msg.name == 'terminate' and msg.target == self.id:
self.state = 'aborted'
channel.send(
Message(name='aborted', target=self.parent_id, origin=self.id))
result = 'consumed'
return result
def _was_activated(self, channel, msg, guard=lambda: True):
"""Check if it's activation message."""
if self._is_start_message(msg):
if not guard():
LOG.debug("Conditions for %r don't hold", self)
self.state = 'completed'
channel.send(
Message(name='completed',
origin=self.id,
target=self.parent_id))
return 'consumed'
if len(self.children) > 0:
self.state = 'active'
channel.send(
Message(name='start',
origin=self.id,
target=self.children[0].id))
else:
self.state = 'completed'
channel.send(
Message(name='completed',
origin=self.id,
target=self.parent_id))
return 'consumed'
else:
return ''
def _was_sequence_completed(self,
channel,
msg,
guard=lambda: True,
compensate=lambda: None):
"""Check if all children in sequence were completed."""
res = ''
if self._is_complete_message(msg):
for index, child in zip(range(0, len(self.children)),
self.children):
if child.id == msg.origin:
if (index + 1) < len(self.children):
channel.send(
Message(name='start',
origin=self.id,
target="%s_%d" % (self.id, index + 1)))
else:
if guard():
self.state = 'completed'
channel.send(
Message(name='completed',
origin=self.id,
target=self.parent_id))
else:
compensate()
res = 'consumed'
break
return res
def _was_consumed_by_child(self, channel, msg):
"""Check if a child consumed the message."""
for child in self.children:
if msg.target.startswith(child.id):
return child.handle_message(channel, msg)
if self.state == 'aborting' and self.faults and \
msg.target.startswith(self.faults.id):
return self.faults.handle_message(channel, msg)
def _is_start_message(self, msg):
"""Return True if the message destined to start the activity."""
return self.state == 'ready' and msg.name == 'start' \
and msg.target == self.id
def _is_complete_message(self, msg):
"""Return True if the message is from completed child."""
return self.state == 'active' and msg.name == 'completed' \
and msg.target == self.id
def reset_children(self):
"""Reset children state to ready."""
for child in self.children:
child.state = 'ready'
child.reset_children()
