use lock to protect the thread id info

source/darwin/dispatch_queue_event_loop.c

@@ -72,8 +72,7 @@ struct dispatch_loop {
     dispatch_queue_t dispatch_queue;
     struct aws_task_scheduler scheduler;
     struct aws_linked_list local_cross_thread_tasks;
-    aws_thread_id_t m_current_thread_id;
-    bool processing;
+
     // Apple dispatch queue uses the id string to identify the dispatch queue
     struct aws_string *dispatch_queue_id;
 
@@ -82,6 +81,9 @@ struct dispatch_loop {
         struct aws_linked_list cross_thread_tasks;
         struct aws_mutex lock;
         bool suspended;
+        // `is_executing` flag and `current_thread_id` together are used to identify the excuting thread id for dispatch queue. 
+        bool is_executing;
+        aws_thread_id_t current_thread_id;
     } synced_data;
 
     bool wakeup_schedule_needed;
@@ -231,8 +233,6 @@ static void s_destroy(struct aws_event_loop *event_loop) {
     AWS_LOGF_TRACE(AWS_LS_IO_EVENT_LOOP, "id=%p: Destroying Dispatch Queue Event Loop", (void *)event_loop);
 
     struct dispatch_loop *dispatch_loop = event_loop->impl_data;
-    dispatch_loop->m_current_thread_id = aws_thread_current_thread_id();
-    dispatch_loop->processing = true;
 
     /* make sure the loop is running so we can schedule a last task. */
     s_run(event_loop);
@@ -242,6 +242,9 @@ static void s_destroy(struct aws_event_loop *event_loop) {
       aws_task_scheduler_clean_up(&dispatch_loop->scheduler);
 
       aws_mutex_lock(&dispatch_loop->synced_data.lock);
+      dispatch_loop->synced_data.current_thread_id = aws_thread_current_thread_id();
+      dispatch_loop->synced_data.is_executing = true;
+      aws_mutex_unlock(&dispatch_loop->synced_data.lock);
       while (!aws_linked_list_empty(&dispatch_loop->synced_data.cross_thread_tasks)) {
           struct aws_linked_list_node *node = aws_linked_list_pop_front(&dispatch_loop->synced_data.cross_thread_tasks);
           struct aws_task *task = AWS_CONTAINER_OF(node, struct aws_task, node);
@@ -261,11 +264,10 @@ static void s_destroy(struct aws_event_loop *event_loop) {
           scheduled_service_entry_destroy(entry);
       }
 
+      aws_mutex_lock(&dispatch_loop->synced_data.lock);
       dispatch_loop->synced_data.suspended = true;
+      dispatch_loop->synced_data.is_executing = false;
       aws_mutex_unlock(&dispatch_loop->synced_data.lock);
-
-      dispatch_loop->m_current_thread_id = aws_thread_current_thread_id();
-      dispatch_loop->processing = false;
     });
 
     AWS_LOGF_TRACE(AWS_LS_IO_EVENT_LOOP, "id=%p: Releasing Dispatch Queue.", (void *)event_loop);
@@ -398,19 +400,22 @@ void run_iteration(void *context) {
         }
     }
 
-    dispatch_loop->m_current_thread_id = aws_thread_current_thread_id();
-    dispatch_loop->processing = true;
+    aws_mutex_lock(&dispatch_loop->synced_data.lock);
+    dispatch_loop->synced_data.current_thread_id = aws_thread_current_thread_id();
+    dispatch_loop->synced_data.is_executing = true;
+    aws_mutex_unlock(&dispatch_loop->synced_data.lock);
 
     // run all scheduled tasks
     uint64_t now_ns = 0;
     aws_event_loop_current_clock_time(event_loop, &now_ns);
     aws_task_scheduler_run_all(&dispatch_loop->scheduler, now_ns);
     aws_event_loop_register_tick_end(event_loop);
 
-    end_iteration(entry);
+    aws_mutex_lock(&dispatch_loop->synced_data.lock);
+    dispatch_loop->synced_data.is_executing = false;
+    aws_mutex_unlock(&dispatch_loop->synced_data.lock);
 
-    dispatch_loop->m_current_thread_id = aws_thread_current_thread_id();
-    dispatch_loop->processing = false;
+    end_iteration(entry);
 }
 
 // Checks if a new iteration task needs to be scheduled, given a target timestamp
@@ -499,7 +504,9 @@ static int s_unsubscribe_from_io_events(struct aws_event_loop *event_loop, struc
 // dispatch queue.
 static bool s_is_on_callers_thread(struct aws_event_loop *event_loop) {
     struct dispatch_loop *dispatch_queue = event_loop->impl_data;
-    bool result = dispatch_queue->processing &&
-                  aws_thread_thread_id_equal(dispatch_queue->m_current_thread_id, aws_thread_current_thread_id());
+    aws_mutex_lock(&dispatch_queue->synced_data.lock);
+    bool result = dispatch_queue->synced_data.is_executing &&
+                  aws_thread_thread_id_equal(dispatch_queue->synced_data.current_thread_id, aws_thread_current_thread_id());
+    aws_mutex_unlock(&dispatch_queue->synced_data.lock);
     return result;
 }