def __init__(self, activity):
try:
assert(IActivity.providedBy(activity))
except AssertionError:
raise ActivityRuntimeError,\
" ActivityRuntime must be initialized with an Activity instance"
self.activity = activity
self.token_pool = TokenPool()
class ActivityRuntime(object):
implements(IActivityRuntime)
def __init__(self, activity):
try:
assert(IActivity.providedBy(activity))
except AssertionError:
raise ActivityRuntimeError,\
" ActivityRuntime must be initialized with an Activity instance"
self.activity = activity
self.token_pool = TokenPool()
def start(self, data=None):
try:
assert(len(self.token_pool) == 0)
except AssertionError:
raise ActivityRuntimeError,\
"A active activity cannot be re-started."
self._eval_constraints(self.activity.preconditions, data)
for profile in self.activity.package.profiles:
# Importing executions associated with model
# Imported modules are not available because they are not bound
# to a variable. but we just want to execute modules and register
# utilities here.
__import__(profile.__name__)
# TODO: check guard conditions for outgoing_nodes here?
for node in self.activity.filtereditems(IInitialNode):
for edge in node.outgoing_edges:
self._create_token(edge, data)
self._unlock_token()
def stop(self):
log.info('stopping activity')
del self.token_pool[:]
def next(self):
data_output = {}
do_stop = False
for node in self.activity.nodes:
# TODO: if node is still executing (and may not be a reentrant or
# so), don't let it execute again. only needed for asyn behavior
# InitialNode only considered at runtime-start
if IInitialNode.providedBy(node):
continue
### Is node executable?
is_merge_node = IMergeNode.providedBy(node)
can_execute = not is_merge_node # TODO: i don't like this construct
for edge in node.incoming_edges:
tokens = getMultiAdapter((self.token_pool, edge), ITokenFilter)
tok = [tk for tk in tokens if not tk.lock]
if is_merge_node:
# merge behavior: any token on any edge fires node
can_execute = can_execute or tok
else:
# implicit and explicit synchronisation (join, et. al):
# only when all tokens are present, node is fired.
can_execute = can_execute and tok
if not can_execute:
continue
### Getting and destroying tokens and merging data
data = {}
for edge in node.incoming_edges:
tokens = getMultiAdapter((self.token_pool, edge), ITokenFilter)
for token in tokens:
if token.lock:
# don't manipulate locked tokens (in case of IMergeNode)
continue
# merge the token's data
data = self._merge_data(data, token.data)
# when nodes execute, tokens are deleted
self.token_pool.remove(token)
### Executing actions
do_set_tokens = True
if IAction.providedBy(node):
self._eval_constraints(node.preconditions, data)
data = self._execute(node, data)
self._eval_constraints(node.postconditions, data)
# contract: if data is none, there is async behavior and action
# is still executing.
# if data is not none, processing on node can continue
# TODO: check this contract, formalise and document it.
do_set_tokens = data is not None
if not do_set_tokens:
continue
# TODO: UML2's MergeNode behavior does not reduce concurrency
# here the concurrency is reduced if 2 tokens come into the node
# at a time. THIS SHOULD BE CHANGED...
### Setting tokens
else_branch = None
for edge in node.outgoing_edges:
if edge.guard \
and not edge.guard == "else" \
and not eval(edge.guard, None, data):
continue
elif edge.guard == "else" and else_branch is None:
else_branch = edge
else:
else_branch = False
# create tokens for outgoing edges
self._create_token(edge, data)
if IDecisionNode.providedBy(node):
# XOR semantic for DecisionNode: only one outgoing edge
# can traverse.
break
if IActivityEdge.providedBy(else_branch):
self._create_token(else_branch, data)
### Prepare for FinalNode if so
# Collecting data from tokens running into IFinalNode
# TODO: only when reaching IFinalNode data is returned?
if IFinalNode.providedBy(node):
data_output = self._merge_data(data_output, data)
# The activity must be stopped when ActivityFinalNode is reached
# But let other tokens be processed before. The order in which a
# Token reaches ActivityFinalNode is not deterministic anyways.
if IActivityFinalNode.providedBy(node):
do_stop = True
# after all nodes processed, unlock the tokens created in this run
self._unlock_token()
if do_stop:
self.stop()
# TODO: does this really mean that activity is reached it's end or is
# it just an implicit stop? len(self.token_pool) == 0
# maybe do_stop should apply here
# TODO: should token be erased before postconstraints are evaluated?
# maybe better before, so that tokens are preserved and activity is
# hindered to stop
if len(self.token_pool) == 0:
self._eval_constraints(self.activity.postconditions, data_output)
if data_output:
return data_output
def print_token_state(self):
for token in self.token_pool:
print(self.activity.node(token.edge_uuid).__name__
+ ': '
+ str(token)
+ ', data: ' + str(token.data)
)
# convinience
ts = print_token_state
def _eval_constraints(self, constraints, data=None):
for constr in constraints:
try:
assert(eval(constr.specification, None, data))
except (NameError, AssertionError):
raise ActivityRuntimeError,\
constr.__class__.__name__ + ' not fulfilled: "' +\
constr.specification + '"'
def _merge_data(self, data_dict, new_data_dict):
for key in data_dict.keys():
if key in new_data_dict.keys():
if data_dict[key] is not new_data_dict[key]:
raise ActivityRuntimeError,\
"""Failed to merge token data:
Same key, different values"""
data_dict.update(new_data_dict)
return data_dict
def _unlock_token(self):
# TOKEN LOCK:
# locked token's should not be considered for node execution in current
# step. wait for next step.
# token lock exist because we want tokens only be passed by one node
# per step.
# TOKEN MUST BE UNLOCKED HERE
for token in self.token_pool:
token.lock = False
def _create_token(self, edge, data=None):
"""Helper method to ease token creation.
"""
# token should not be modified more than once per iteration
# therefore lock=True
self.token_pool.append(
Token(edge_uuid=edge.uuid, data=data, lock=True)
)
def _execute(self, action, data):
action_info = IActionInfo(action)
for stereotype in action.stereotypes:
tgv_dict = ITaggedValueDict(stereotype)
execution = getUtility(IExecution, name=stereotype.__name__)
data = execution(action_info, tgv_dict, data)
log.info('executing: "' + action.__name__ + '"')
return data
def _receive(self, action_uuid, data=None):
# create tokens with data for action with uuid
pass
