add pre/post execute/retry callbacks to tasks

This enables us to execute code to set up or tear down
global state in running tasks.

Change-Id: Ib1e5d03ab46b3ce1d03fa83b91bf437fa950b758
Implements: blueprint task-callbacks

1 files changed, 6 insertions, 0 deletions

diff --git a/taskflow/engines/action_engine/executor.py b/taskflow/engines/action_engine/executor.py
index 816060f..e28e863 100644
--- a/taskflow/engines/action_engine/executor.py
+++ b/taskflow/engines/action_engine/executor.py
@@ -31,11 +31,14 @@ REVERTED = 'reverted'
 def _execute_task(task, arguments, progress_callback):
     with task.autobind('update_progress', progress_callback):
         try:
+            task.pre_execute()
             result = task.execute(**arguments)
         except Exception:
             # NOTE(imelnikov): wrap current exception with Failure
             # object and return it.
             result = misc.Failure()
+        finally:
+            task.post_execute()
     return (task, EXECUTED, result)
 
 
@@ -45,11 +48,14 @@ def _revert_task(task, arguments, result, failures, progress_callback):
     kwargs['flow_failures'] = failures
     with task.autobind('update_progress', progress_callback):
         try:
+            task.pre_revert()
             result = task.revert(**kwargs)
         except Exception:
             # NOTE(imelnikov): wrap current exception with Failure
             # object and return it.
             result = misc.Failure()
+        finally:
+            task.post_revert()
     return (task, REVERTED, result)