mark dependant tasks failed upon failure

src/api-service/__app__/onefuzzlib/tasks/main.py

@@ -204,7 +204,9 @@ def mark_stopping(self) -> None:
             )
         )
 
-    def mark_failed(self, error: Error) -> None:
+    def mark_failed(
+        self, error: Error, tasks_in_job: Optional[List["Task"]] = None
+    ) -> None:
         if self.state in [TaskState.stopped, TaskState.stopping]:
             logging.debug(
                 "ignoring post-task stop failures for %s:%s", self.job_id, self.task_id
@@ -224,6 +226,25 @@ def mark_failed(self, error: Error) -> None:
             )
         )
 
+        self.mark_dependants_failed(tasks_in_job=tasks_in_job)
+
+    def mark_dependants_failed(
+        self, tasks_in_job: Optional[List["Task"]] = None
+    ) -> None:
+        if tasks_in_job is None:
+            tasks_in_job = Task.search(query={"job_id": [self.job_id]})
+
+        for task in tasks_in_job:
+            if task.config.prereq_tasks:
+                if self.task_id in task.config.prereq_tasks:
+                    task.mark_failed(
+                        Error(
+                            code=ErrorCode.TASK_FAILED,
+                            errors=["prerequisite task failed"],
+                        ),
+                        tasks_in_job,
+                    )
+
     def get_pool(self) -> Optional[Pool]:
         if self.config.pool:
             pool = Pool.get_by_name(self.config.pool.pool_name)