Improve Cancellation Semantics (#413)

If a workflow is cancelled, it should throw
DBOSAwaitedWorkflowCancelledError, not DBOSWorkflowCancelledError, to
its caller.

Author: kraftp

dbos/_core.py

@@ -49,6 +49,7 @@
     get_local_dbos_context,
 )
 from ._error import (
+    DBOSAwaitedWorkflowCancelledError,
     DBOSException,
     DBOSMaxStepRetriesExceeded,
     DBOSNonExistentWorkflowError,
@@ -370,7 +371,7 @@ def persist(func: Callable[[], R]) -> R:
             r: R = dbos._sys_db.await_workflow_result(status["workflow_uuid"])
             return r
         except DBOSWorkflowCancelledError as error:
-            raise
+            raise DBOSAwaitedWorkflowCancelledError(status["workflow_uuid"])
         except Exception as error:
             if not dbos.debug_mode:
                 dbos._sys_db.update_workflow_outcome(

tests/test_admin_server.py

@@ -20,7 +20,7 @@
     WorkflowHandle,
     _workflow_commands,
 )
-from dbos._error import DBOSWorkflowCancelledError
+from dbos._error import DBOSAwaitedWorkflowCancelledError
 from dbos._schemas.system_database import SystemSchema
 from dbos._sys_db import SystemDatabase, WorkflowStatusString
 from dbos._utils import INTERNAL_QUEUE_NAME, GlobalParams
@@ -306,7 +306,7 @@ def blocking_workflow() -> None:
     )
     assert response.status_code == 204
     event.set()
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     info = _workflow_commands.get_workflow(sys_db, wfid)
     assert info is not None
@@ -750,7 +750,7 @@ def workflow() -> None:
         timeout=5,
     )
     response.raise_for_status()
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
 
 

tests/test_async.py

@@ -18,7 +18,7 @@
 from dbos._context import assert_current_dbos_context
 from dbos._dbos import WorkflowHandle
 from dbos._dbos_config import ConfigFile
-from dbos._error import DBOSException, DBOSWorkflowCancelledError
+from dbos._error import DBOSAwaitedWorkflowCancelledError, DBOSException
 
 
 @pytest.mark.asyncio
@@ -492,20 +492,20 @@ async def blocked_workflow() -> None:
             DBOS.sleep(0.1)
 
     with SetWorkflowTimeout(0.1):
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             await blocked_workflow()
         handle = await DBOS.start_workflow_async(blocked_workflow)
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             await handle.get_result()
 
     @DBOS.workflow()
     async def parent_workflow_with_timeout() -> None:
         assert assert_current_dbos_context().workflow_deadline_epoch_ms is None
         with SetWorkflowTimeout(0.1):
-            with pytest.raises(DBOSWorkflowCancelledError):
+            with pytest.raises(DBOSAwaitedWorkflowCancelledError):
                 await blocked_workflow()
             handle = await DBOS.start_workflow_async(blocked_workflow)
-            with pytest.raises(DBOSWorkflowCancelledError):
+            with pytest.raises(DBOSAwaitedWorkflowCancelledError):
                 await handle.get_result()
         assert assert_current_dbos_context().workflow_deadline_epoch_ms is None
 
@@ -526,7 +526,7 @@ async def parent_workflow() -> None:
     # Verify if a parent called with a timeout calls a blocked child
     # the deadline propagates and the children are also cancelled.
     with SetWorkflowTimeout(1.0):
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             await parent_workflow()
 
     with pytest.raises(Exception) as exc_info:

tests/test_async_workflow_management.py

@@ -7,7 +7,7 @@
 import pytest
 
 from dbos import DBOS, Queue, SetWorkflowID
-from dbos._error import DBOSWorkflowCancelledError
+from dbos._error import DBOSAwaitedWorkflowCancelledError
 from dbos._sys_db import StepInfo, WorkflowStatus
 from tests.conftest import queue_entries_are_cleaned_up
 
@@ -46,7 +46,7 @@ def simple_workflow(x: int) -> int:
     await DBOS.cancel_workflow_async(wfid)
     workflow_event.set()
 
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     assert steps_completed == 1
 
@@ -85,7 +85,7 @@ def simple_workflow(x: int) -> int:
     DBOS.cancel_workflow(wfid)
     workflow_event.set()
 
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     assert steps_completed == 1
 

tests/test_dbos.py

@@ -28,7 +28,6 @@
     DBOSAwaitedWorkflowCancelledError,
     DBOSConflictingRegistrationError,
     DBOSMaxStepRetriesExceeded,
-    DBOSWorkflowCancelledError,
 )
 from dbos._schemas.system_database import SystemSchema
 from dbos._sys_db import GetWorkflowsInput
@@ -1493,7 +1492,7 @@ def blocked_workflow() -> None:
     # Verify a blocked workflow called with a timeout is cancelled
     wfid = str(uuid.uuid4())
     with SetWorkflowTimeout(0.1):
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             with SetWorkflowID(wfid):
                 blocked_workflow()
         assert assert_current_dbos_context().workflow_deadline_epoch_ms is None
@@ -1505,7 +1504,7 @@ def blocked_workflow() -> None:
             status.workflow_deadline_epoch_ms is not None
             and status.workflow_deadline_epoch_ms > start_time
         )
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             handle.get_result()
 
     # Change the workflow status to pending
@@ -1518,17 +1517,17 @@ def blocked_workflow() -> None:
     # Recover the workflow, verify it still times out
     handles = DBOS._recover_pending_workflows()
     assert len(handles) == 1
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handles[0].get_result()
 
     @DBOS.workflow()
     def parent_workflow_with_timeout() -> None:
         assert assert_current_dbos_context().workflow_deadline_epoch_ms is None
         with SetWorkflowTimeout(0.1):
-            with pytest.raises(DBOSWorkflowCancelledError):
+            with pytest.raises(DBOSAwaitedWorkflowCancelledError):
                 blocked_workflow()
             handle = DBOS.start_workflow(blocked_workflow)
-            with pytest.raises(DBOSWorkflowCancelledError):
+            with pytest.raises(DBOSAwaitedWorkflowCancelledError):
                 handle.get_result()
         assert assert_current_dbos_context().workflow_deadline_epoch_ms is None
 
@@ -1549,7 +1548,7 @@ def parent_workflow() -> None:
     # Verify if a parent called with a timeout calls a blocked child
     # the deadline propagates and the children are also cancelled.
     with SetWorkflowTimeout(1.0):
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             parent_workflow()
 
     with pytest.raises(DBOSAwaitedWorkflowCancelledError):

tests/test_queue.py

@@ -1,5 +1,4 @@
 import asyncio
-import logging
 import multiprocessing
 import multiprocessing.synchronize
 import os
@@ -27,7 +26,7 @@
 )
 from dbos._context import assert_current_dbos_context
 from dbos._dbos import WorkflowHandleAsync
-from dbos._error import DBOSAwaitedWorkflowCancelledError, DBOSWorkflowCancelledError
+from dbos._error import DBOSAwaitedWorkflowCancelledError
 from dbos._schemas.system_database import SystemSchema
 from dbos._sys_db import WorkflowStatusString
 from dbos._utils import GlobalParams
@@ -943,7 +942,7 @@ def blocked_parent_workflow() -> None:
 
     with SetWorkflowTimeout(1.0):
         handle = DBOS.start_workflow(blocked_parent_workflow)
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         DBOS.retrieve_workflow(child_id).get_result()

tests/test_workflow_management.py

@@ -9,7 +9,7 @@
 # Public API
 from dbos import DBOS, Queue, SetWorkflowID
 from dbos._dbos import DBOSConfiguredInstance
-from dbos._error import DBOSWorkflowCancelledError
+from dbos._error import DBOSAwaitedWorkflowCancelledError
 from dbos._schemas.application_database import ApplicationSchema
 from dbos._utils import INTERNAL_QUEUE_NAME, GlobalParams
 from dbos._workflow_commands import garbage_collect, global_timeout
@@ -52,7 +52,7 @@ def simple_workflow(x: int) -> int:
     main_thread_event.wait()
     DBOS.cancel_workflow(wfid)
     workflow_event.set()
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     assert steps_completed == 1
 
@@ -103,7 +103,7 @@ def simple_workflow(x: int) -> int:
     main_thread_event.wait()
     DBOS.cancel_workflow(wfid)
     workflow_event.set()
-    with pytest.raises(DBOSWorkflowCancelledError):
+    with pytest.raises(DBOSAwaitedWorkflowCancelledError):
         handle.get_result()
     assert txn_completed == 1
 
@@ -746,7 +746,7 @@ def blocked_workflow() -> str:
 
     # Verify all workflows started before the global timeout are cancelled
     for handle in handles:
-        with pytest.raises(DBOSWorkflowCancelledError):
+        with pytest.raises(DBOSAwaitedWorkflowCancelledError):
             handle.get_result()
     event.set()
     assert final_handle.get_result() is not None