Add SWF endpoint PollForDecisionTask and associated DecisionTask model

moto/swf/models/__init__.py

@@ -13,6 +13,7 @@ from ..exceptions import (
     SWFTypeDeprecatedFault,
 )
 from .activity_type import ActivityType
+from .decision_task import DecisionTask
 from .domain import Domain
 from .generic_type import GenericType
 from .history_event import HistoryEvent
@@ -162,6 +163,36 @@ class SWFBackend(BaseBackend):
         domain = self._get_domain(domain_name)
         return domain.get_workflow_execution(run_id, workflow_id)
 
+    def poll_for_decision_task(self, domain_name, task_list, identity=None):
+        self._check_string(domain_name)
+        self._check_string(task_list)
+        domain = self._get_domain(domain_name)
+        # Real SWF cases:
+        # - case 1: there's a decision task to return, return it
+        # - case 2: there's no decision task to return, so wait for timeout
+        #           and if a new decision is schedule, start and return it
+        # - case 3: timeout reached, no decision, return an empty decision
+        #           (e.g. a decision with an empty "taskToken")
+        #
+        # For the sake of simplicity, we forget case 2 for now, so either
+        # there's a DecisionTask to return, either we return a blank one.
+        #
+        # SWF client libraries should cope with that easily as long as tests
+        # aren't distributed.
+        #
+        # TODO: handle long polling (case 2) for decision tasks
+        decision_candidates = []
+        for wf_id, wf_execution in domain.workflow_executions.iteritems():
+            decision_candidates += wf_execution.scheduled_decision_tasks
+        if any(decision_candidates):
+            # TODO: handle task priorities (but not supported by boto for now)
+            decision = min(decision_candidates, key=lambda d: d.scheduled_at)
+            wfe = decision.workflow_execution
+            wfe.start_decision_task(decision.task_token, identity=identity)
+            return decision
+        else:
+            return None
+
 
 swf_backends = {}
 for region in boto.swf.regions():

moto/swf/models/decision_task.py

@@ -0,0 +1,35 @@
+from __future__ import unicode_literals
+from datetime import datetime
+import uuid
+
+
+class DecisionTask(object):
+    def __init__(self, workflow_execution, scheduled_event_id):
+        self.workflow_execution = workflow_execution
+        self.workflow_type = workflow_execution.workflow_type
+        self.task_token = str(uuid.uuid4())
+        self.scheduled_event_id = scheduled_event_id
+        self.previous_started_event_id = 0
+        self.started_event_id = None
+        self.state = "SCHEDULED"
+        # this is *not* necessarily coherent with workflow execution history,
+        # but that shouldn't be a problem for tests
+        self.scheduled_at = datetime.now()
+
+    def to_full_dict(self):
+        hsh = {
+            "events": [
+                evt.to_dict() for evt in self.workflow_execution.events
+            ],
+            "taskToken": self.task_token,
+            "previousStartedEventId": self.previous_started_event_id,
+            "workflowExecution": self.workflow_execution.to_short_dict(),
+            "workflowType": self.workflow_type.to_short_dict(),
+        }
+        if self.started_event_id:
+            hsh["startedEventId"] = self.started_event_id
+        return hsh
+
+    def start(self, started_event_id):
+        self.state = "STARTED"
+        self.started_event_id = started_event_id

moto/swf/models/history_event.py

@@ -50,9 +50,12 @@ class HistoryEvent(object):
                 "taskList": {"name": wfe.task_list}
             }
         elif self.event_type == "DecisionTaskStarted":
-            return {
+            hsh = {
                 "scheduledEventId": self.scheduled_event_id
             }
+            if hasattr(self, "identity") and self.identity:
+                hsh["identity"] = self.identity
+            return hsh
         else:
             raise NotImplementedError(
                 "HistoryEvent does not implement attributes for type '{}'".format(self.event_type)

moto/swf/models/workflow_execution.py

@@ -4,6 +4,7 @@ import uuid
 from moto.core.utils import camelcase_to_underscores
 
 from ..exceptions import SWFDefaultUndefinedFault
+from .decision_task import DecisionTask
 from .history_event import HistoryEvent
 
 
@@ -32,6 +33,10 @@ class WorkflowExecution(object):
         }
         # events
         self.events = []
+        # tasks
+        self.decision_tasks = []
+        self.activity_tasks = []
+        self.child_workflow_executions = []
 
     def __repr__(self):
         return "WorkflowExecution(run_id: {})".format(self.run_id)
@@ -99,13 +104,44 @@ class WorkflowExecution(object):
     def _add_event(self, *args, **kwargs):
         evt = HistoryEvent(self.next_event_id(), *args, **kwargs)
         self.events.append(evt)
+        return evt
 
     def start(self):
         self._add_event(
             "WorkflowExecutionStarted",
             workflow_execution=self,
         )
-        self._add_event(
+        self.schedule_decision_task()
+
+    def schedule_decision_task(self):
+        self.open_counts["openDecisionTasks"] += 1
+        evt = self._add_event(
             "DecisionTaskScheduled",
             workflow_execution=self,
         )
+        self.decision_tasks.append(DecisionTask(self, evt.event_id))
+
+    @property
+    def scheduled_decision_tasks(self):
+        return filter(
+            lambda t: t.state == "SCHEDULED",
+            self.decision_tasks
+        )
+
+    def _find_decision_task(self, task_token):
+        for dt in self.decision_tasks:
+            if dt.task_token == task_token:
+                return dt
+        raise ValueError(
+            "No decision task with token: {}".format(task_token)
+        )
+
+    def start_decision_task(self, task_token, identity=None):
+        dt = self._find_decision_task(task_token)
+        evt = self._add_event(
+            "DecisionTaskStarted",
+            workflow_execution=self,
+            scheduled_event_id=dt.scheduled_event_id,
+            identity=identity
+        )
+        dt.start(evt.event_id)