Implement decision state machine #8
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shijiesheng
reviewed
Aug 14, 2025
| MUTABLE_SIDE_EFFECT_MARKER_NAME = "MutableSideEffect" | ||
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| def decision_state_to_string(state: DecisionState) -> str: |
| return f"DecisionType: {decision_type_to_string(self.decision_type)}, ID: {self.id}" | ||
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| class DecisionStateMachine: |
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nit: BaseDecisionStateMachine
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| def get_id(self) -> str: | ||
| raise NotImplementedError | ||
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| # Typed handlers (Go-parity naming semantics) | ||
| def handle_initiated_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_started_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_completion_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_initiation_failed_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_cancel_initiated_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_cancel_failed_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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| def handle_canceled_event(self, event: history.HistoryEvent) -> None: | ||
| pass | ||
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I think we should just return NotImplemented Error for those method. What do you think about this?
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| def get_id(self) -> str: | ||
| return self.activity_id | ||
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| def handle_initiated_event(self, event: history.HistoryEvent) -> None: | ||
| a = getattr(event, "activity_task_scheduled_event_attributes", None) | ||
| if a is not None and a.activity_id == self.activity_id: | ||
| self.status = MachineStatus.SCHEDULED | ||
| self.scheduled_event_id = event.event_id |
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at least these two can be moved to Base class. check go sdk to get the full list
| TIMED_OUT = auto() | ||
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| class DecisionState(Enum): |
| ) | ||
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| class MachineStatus(Enum): |
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| # Event name constants (used by Go state machine; provided for parity/testing/logs) | ||
| EVENT_CANCEL = "cancel" | ||
| EVENT_DECISION_SENT = "handleDecisionSent" | ||
| EVENT_INITIATED = "handleInitiatedEvent" | ||
| EVENT_INITIATION_FAILED = "handleInitiationFailedEvent" | ||
| EVENT_STARTED = "handleStartedEvent" | ||
| EVENT_COMPLETION = "handleCompletionEvent" | ||
| EVENT_CANCEL_INITIATED = "handleCancelInitiatedEvent" | ||
| EVENT_CANCEL_FAILED = "handleCancelFailedEvent" | ||
| EVENT_CANCELED = "handleCanceledEvent" | ||
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| # Marker names | ||
| SIDE_EFFECT_MARKER_NAME = "SideEffect" | ||
| VERSION_MARKER_NAME = "Version" | ||
| LOCAL_ACTIVITY_MARKER_NAME = "LocalActivity" | ||
| MUTABLE_SIDE_EFFECT_MARKER_NAME = "MutableSideEffect" |
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not sure how these constants are used
| return mapping.get(state, "Unknown") | ||
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| def decision_type_to_string(dt: DecisionType) -> str: |
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What changed?
Implemented decision state machine system for Cadence Python client including:
DecisionStateMachineclass for workflow decision lifecycle trackingActivityDecisionMachinefor activity task scheduling, execution, and cancellationTimerDecisionMachinefor timer operationsChildWorkflowDecisionMachinefor child workflow lifecycle managementDecisionManagerfor aggregating state machines and coordinating decisionsAlso try to use proto types directly and avoid any mapping
(heavily relied on Go client state machine: https://github.com/cadence-workflow/cadence-go-client/blob/master/internal/internal_decision_state_machine.go)
Why?
Workflows need to track what decisions they've made and what state they're in. This state machine ensures decisions are made correctly, in the right order, and handles properly. It's essential for deterministic workflow execution.
How did you test it?
Local unit tests
uv testPotential risks
Release notes
Documentation Changes