[GitHub] [airflow] dstandish commented on a change in pull request #15125: Add latest only decorator

[GitBox <gi...@apache.org>]

dstandish commented on a change in pull request #15125:
URL: https://github.com/apache/airflow/pull/15125#discussion_r605758162



##########
File path: airflow/utils/decorators.py
##########
@@ -97,6 +99,44 @@ def wrapper(*args: Any, **kwargs: Any) -> Any:
     return cast(T, wrapper)
 
 
+def latest_only(f):
+    """
+    Decorator for adding skip-if-not-latest behavior to any operator.
+
+    Can be disabled if the class has an attribute ``latest_only`` with value ``False``
+    """
+
+    def skip_if_not_latest(context):
+        if not context:  # assume run interactively
+            return
+        dag_run = context.get('dag_run')
+        if dag_run and dag_run.external_trigger:
+            print("Externally triggered DAG_Run: allowing execution to proceed.")
+            return
+
+        dag = context['dag']
+        now = pendulum.now('UTC')
+        left_window = dag.following_schedule(context['execution_date'])
+        right_window = dag.following_schedule(left_window)
+        print(
+            f"Checking latest only:\n"
+            f"\tleft_window: {left_window}\n"
+            f"\tright_window: {right_window}\n"
+            f"\tnow: {now}\n",
+        )
+
+        if not left_window < now <= right_window:
+            raise AirflowSkipException('Not latest execution; skipping...')
+
+    @wraps(f)
+    def wrap(self, context):
+        if not (hasattr(self, 'latest_only') and self.latest_only is False):

Review comment:
       What this does is make it so you can build a custom operator that has optional latest only behavior. So when it is used, the user can use latest only on most cases, but say in one dag disable.




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