Expose workflow cancel cause

core/src/core_tests/child_workflows.rs

@@ -92,7 +92,7 @@ async fn parent_cancels_child_wf(ctx: WfContext) -> WorkflowResult<()> {
         .await
         .into_started()
         .expect("Child should get started");
-    start_res.cancel(&ctx);
+    start_res.cancel(&ctx, "cancel reason".to_string());
     let stat = start_res
         .result()
         .await
@@ -157,6 +157,7 @@ async fn cancel_child_workflow_lang_thinks_not_started_but_is(
         act.run_id,
         CancelChildWorkflowExecution {
             child_workflow_seq: 1,
+            reason: "dieee".to_string(),
         }
         .into(),
     ))
@@ -215,6 +216,7 @@ async fn cancel_already_complete_child_ignored() {
         vec![
             CancelChildWorkflowExecution {
                 child_workflow_seq: 1,
+                reason: "go away!".to_string(),
             }
             .into(),
             CompleteWorkflowExecution { result: None }.into(),

core/src/worker/workflow/machines/activity_state_machine.rs

@@ -1,8 +1,8 @@
 #![allow(clippy::large_enum_variant)]
 
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::{
     abstractions::dbg_panic,
@@ -164,6 +164,45 @@ impl ActivityMachine {
             is_local: false,
         }
     }
+
+    pub(super) fn cancel(&mut self) -> Result<Vec<MachineResponse>, MachineError<WFMachinesError>> {
+        if matches!(
+            self.state(),
+            ActivityMachineState::Completed(_)
+                | ActivityMachineState::Canceled(_)
+                | ActivityMachineState::Failed(_)
+                | ActivityMachineState::TimedOut(_)
+        ) {
+            // Ignore attempted cancels in terminal states
+            debug!(
+                "Attempted to cancel already resolved activity (seq {})",
+                self.shared_state.attrs.seq
+            );
+            return Ok(vec![]);
+        }
+        let event = match self.shared_state.cancellation_type {
+            ActivityCancellationType::Abandon => ActivityMachineEvents::Abandon,
+            _ => ActivityMachineEvents::Cancel,
+        };
+        let vec = OnEventWrapper::on_event_mut(self, event)?;
+        let res = vec
+            .into_iter()
+            .flat_map(|amc| match amc {
+                ActivityMachineCommand::RequestCancellation(cmd) => {
+                    self.machine_responses_from_cancel_request(cmd)
+                }
+                ActivityMachineCommand::Cancel(details) => {
+                    vec![self.create_cancelation_resolve(details).into()]
+                }
+                x => panic!("Invalid cancel event response {x:?}"),
+            })
+            .collect();
+        Ok(res)
+    }
+
+    pub(super) fn was_cancelled_before_sent_to_server(&self) -> bool {
+        self.shared_state().cancelled_before_sent
+    }
 }
 
 impl TryFrom<HistEventData> for ActivityMachineEvents {
@@ -299,47 +338,6 @@ impl TryFrom<CommandType> for ActivityMachineEvents {
     }
 }
 
-impl Cancellable for ActivityMachine {
-    fn cancel(&mut self) -> Result<Vec<MachineResponse>, MachineError<Self::Error>> {
-        if matches!(
-            self.state(),
-            ActivityMachineState::Completed(_)
-                | ActivityMachineState::Canceled(_)
-                | ActivityMachineState::Failed(_)
-                | ActivityMachineState::TimedOut(_)
-        ) {
-            // Ignore attempted cancels in terminal states
-            debug!(
-                "Attempted to cancel already resolved activity (seq {})",
-                self.shared_state.attrs.seq
-            );
-            return Ok(vec![]);
-        }
-        let event = match self.shared_state.cancellation_type {
-            ActivityCancellationType::Abandon => ActivityMachineEvents::Abandon,
-            _ => ActivityMachineEvents::Cancel,
-        };
-        let vec = OnEventWrapper::on_event_mut(self, event)?;
-        let res = vec
-            .into_iter()
-            .flat_map(|amc| match amc {
-                ActivityMachineCommand::RequestCancellation(cmd) => {
-                    self.machine_responses_from_cancel_request(cmd)
-                }
-                ActivityMachineCommand::Cancel(details) => {
-                    vec![self.create_cancelation_resolve(details).into()]
-                }
-                x => panic!("Invalid cancel event response {x:?}"),
-            })
-            .collect();
-        Ok(res)
-    }
-
-    fn was_cancelled_before_sent_to_server(&self) -> bool {
-        self.shared_state().cancelled_before_sent
-    }
-}
-
 #[derive(Clone)]
 pub(super) struct SharedState {
     scheduled_event_id: i64,

core/src/worker/workflow/machines/cancel_external_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::worker::workflow::machines::HistEventData;
 use rustfsm::{fsm, StateMachine, TransitionResult};
@@ -208,8 +208,6 @@ impl WFMachinesAdapter for CancelExternalMachine {
     }
 }
 
-impl Cancellable for CancelExternalMachine {}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -222,11 +220,14 @@ mod tests {
 
     async fn cancel_sender(ctx: WfContext) -> WorkflowResult<()> {
         let res = ctx
-            .cancel_external(NamespacedWorkflowExecution {
-                namespace: "some_namespace".to_string(),
-                workflow_id: "fake_wid".to_string(),
-                run_id: "fake_rid".to_string(),
-            })
+            .cancel_external(
+                NamespacedWorkflowExecution {
+                    namespace: "some_namespace".to_string(),
+                    workflow_id: "fake_wid".to_string(),
+                    run_id: "fake_rid".to_string(),
+                },
+                "cancel reason".to_string(),
+            )
             .await;
         if res.is_err() {
             Err(anyhow::anyhow!("Cancel fail!"))

core/src/worker/workflow/machines/cancel_workflow_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::worker::workflow::machines::HistEventData;
 use rustfsm::{fsm, StateMachine, TransitionResult};
@@ -97,8 +97,6 @@ impl WFMachinesAdapter for CancelWorkflowMachine {
     }
 }
 
-impl Cancellable for CancelWorkflowMachine {}
-
 #[cfg(test)]
 mod tests {
     use super::*;

core/src/worker/workflow/machines/child_workflow_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::{
     internal_flags::CoreInternalFlags,
@@ -54,7 +54,7 @@ fsm! {
     StartCommandCreated --(CommandStartChildWorkflowExecution) --> StartCommandCreated;
     StartCommandCreated --(StartChildWorkflowExecutionInitiated(ChildWorkflowInitiatedData),
         shared on_start_child_workflow_execution_initiated) --> StartEventRecorded;
-    StartCommandCreated --(Cancel, shared on_cancelled) --> Cancelled;
+    StartCommandCreated --(Cancel(String), shared on_cancelled) --> Cancelled;
 
     StartEventRecorded --(ChildWorkflowExecutionStarted(ChildWorkflowExecutionStartedEvent),
         shared on_child_workflow_execution_started) --> Started;
@@ -74,13 +74,13 @@ fsm! {
     // If cancelled after started, we need to issue a cancel external workflow command, and then
     // the child workflow will resolve somehow, so we want to go back to started and wait for that
     // resolution.
-    Started --(Cancel, shared on_cancelled) --> Started;
+    Started --(Cancel(String), shared on_cancelled) --> Started;
     // Abandon & try cancel modes may immediately move to cancelled
-    Started --(Cancel, shared on_cancelled) --> Cancelled;
+    Started --(Cancel(String), shared on_cancelled) --> Cancelled;
     Started --(CommandRequestCancelExternalWorkflowExecution) --> Started;
 
     // Ignore any spurious cancellations after resolution
-    Cancelled --(Cancel) --> Cancelled;
+    Cancelled --(Cancel(String)) --> Cancelled;
     Cancelled --(ChildWorkflowExecutionCancelled,
         on_child_workflow_execution_cancelled) --> Cancelled;
     // Completions of any kind after cancellation are acceptable for abandoned children
@@ -92,10 +92,10 @@ fsm! {
         shared on_child_workflow_execution_timed_out) --> Cancelled;
     Cancelled --(ChildWorkflowExecutionTerminated,
         shared on_child_workflow_execution_terminated) --> Cancelled;
-    Failed --(Cancel) --> Failed;
-    StartFailed --(Cancel) --> StartFailed;
-    TimedOut --(Cancel) --> TimedOut;
-    Completed --(Cancel) --> Completed;
+    Failed --(Cancel(String)) --> Failed;
+    StartFailed --(Cancel(String)) --> StartFailed;
+    TimedOut --(Cancel(String)) --> TimedOut;
+    Completed --(Cancel(String)) --> Completed;
 }
 
 pub(super) struct ChildWorkflowExecutionStartedEvent {
@@ -255,10 +255,14 @@ impl StartCommandCreated {
     pub(super) fn on_cancelled(
         self,
         state: &mut SharedState,
+        reason: String,
     ) -> ChildWorkflowMachineTransition<Cancelled> {
         state.cancelled_before_sent = true;
         ChildWorkflowMachineTransition::commands(vec![ChildWorkflowCommand::StartCancel(Failure {
-            message: "Child Workflow execution cancelled before scheduled".to_owned(),
+            message: format!(
+                "Child Workflow Execution cancelled before scheduled: {}",
+                reason
+            ),
             cause: Some(Box::new(Failure {
                 failure_info: Some(FailureInfo::CanceledFailureInfo(
                     failure::CanceledFailureInfo {
@@ -385,6 +389,7 @@ impl Started {
     fn on_cancelled(
         self,
         state: &mut SharedState,
+        reason: String,
     ) -> ChildWorkflowMachineTransition<StartedOrCancelled> {
         let dest = match state.cancel_type {
             ChildWorkflowCancellationType::Abandon | ChildWorkflowCancellationType::TryCancel => {
@@ -393,9 +398,7 @@ impl Started {
             _ => StartedOrCancelled::Started(Default::default()),
         };
         TransitionResult::ok(
-            [ChildWorkflowCommand::IssueCancelAfterStarted {
-                reason: "Parent workflow requested cancel".to_string(),
-            }],
+            [ChildWorkflowCommand::IssueCancelAfterStarted { reason }],
             dest,
         )
     }
@@ -483,6 +486,30 @@ impl ChildWorkflowMachine {
             }),
         }
     }
+
+    pub(super) fn cancel(
+        &mut self,
+        reason: String,
+    ) -> Result<Vec<MachineResponse>, MachineError<WFMachinesError>> {
+        let event = ChildWorkflowMachineEvents::Cancel(reason);
+        let vec = OnEventWrapper::on_event_mut(self, event)?;
+        let res = vec
+            .into_iter()
+            .map(|mc| match mc {
+                c @ ChildWorkflowCommand::StartCancel(_)
+                | c @ ChildWorkflowCommand::IssueCancelAfterStarted { .. } => {
+                    self.adapt_response(c, None)
+                }
+                x => panic!("Invalid cancel event response {x:?}"),
+            })
+            .flatten_ok()
+            .try_collect()?;
+        Ok(res)
+    }
+
+    pub(super) fn was_cancelled_before_sent_to_server(&self) -> bool {
+        self.shared_state.cancelled_before_sent
+    }
 }
 
 impl TryFrom<HistEventData> for ChildWorkflowMachineEvents {
@@ -713,29 +740,6 @@ impl TryFrom<CommandType> for ChildWorkflowMachineEvents {
     }
 }
 
-impl Cancellable for ChildWorkflowMachine {
-    fn cancel(&mut self) -> Result<Vec<MachineResponse>, MachineError<Self::Error>> {
-        let event = ChildWorkflowMachineEvents::Cancel;
-        let vec = OnEventWrapper::on_event_mut(self, event)?;
-        let res = vec
-            .into_iter()
-            .map(|mc| match mc {
-                c @ ChildWorkflowCommand::StartCancel(_)
-                | c @ ChildWorkflowCommand::IssueCancelAfterStarted { .. } => {
-                    self.adapt_response(c, None)
-                }
-                x => panic!("Invalid cancel event response {x:?}"),
-            })
-            .flatten_ok()
-            .try_collect()?;
-        Ok(res)
-    }
-
-    fn was_cancelled_before_sent_to_server(&self) -> bool {
-        self.shared_state.cancelled_before_sent
-    }
-}
-
 fn failure_info_from_state(state: &SharedState, retry_state: RetryState) -> Option<FailureInfo> {
     Some(FailureInfo::ChildWorkflowExecutionFailureInfo(
         failure::ChildWorkflowExecutionFailureInfo {
@@ -988,7 +992,7 @@ mod test {
                     internal_flags: Rc::new(RefCell::new(InternalFlags::default())),
                 },
             );
-            let cmds = s.cancel().unwrap();
+            let cmds = s.cancel("cancel reason".to_string()).unwrap();
             assert_eq!(cmds.len(), 0);
             assert_eq!(discriminant(&state), discriminant(s.state()));
         }

core/src/worker/workflow/machines/complete_workflow_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::worker::workflow::machines::HistEventData;
 use rustfsm::{fsm, StateMachine, TransitionResult};
@@ -111,5 +111,3 @@ impl WFMachinesAdapter for CompleteWorkflowMachine {
         Ok(vec![])
     }
 }
-
-impl Cancellable for CompleteWorkflowMachine {}

core/src/worker/workflow/machines/continue_as_new_workflow_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    Cancellable, EventInfo, MachineResponse, NewMachineWithCommand, OnEventWrapper,
-    WFMachinesAdapter, WFMachinesError,
+    EventInfo, MachineResponse, NewMachineWithCommand, OnEventWrapper, WFMachinesAdapter,
+    WFMachinesError,
 };
 use crate::worker::workflow::machines::HistEventData;
 use rustfsm::{fsm, StateMachine, TransitionResult};
@@ -105,8 +105,6 @@ impl WFMachinesAdapter for ContinueAsNewWorkflowMachine {
     }
 }
 
-impl Cancellable for ContinueAsNewWorkflowMachine {}
-
 #[cfg(test)]
 mod tests {
     use super::*;

core/src/worker/workflow/machines/fail_workflow_state_machine.rs

@@ -1,6 +1,6 @@
 use super::{
-    workflow_machines::MachineResponse, Cancellable, EventInfo, NewMachineWithCommand,
-    OnEventWrapper, WFMachinesAdapter, WFMachinesError,
+    workflow_machines::MachineResponse, EventInfo, NewMachineWithCommand, OnEventWrapper,
+    WFMachinesAdapter, WFMachinesError,
 };
 use crate::worker::workflow::machines::HistEventData;
 use rustfsm::{fsm, StateMachine, TransitionResult};
@@ -113,5 +113,3 @@ impl WFMachinesAdapter for FailWorkflowMachine {
         Ok(vec![])
     }
 }
-
-impl Cancellable for FailWorkflowMachine {}