Merge pull request #9066 from deepikabhavnani/equeue_chain_fixed

Equeue chaining bug fixes

Author: 0xc0170

UNITTESTS/stubs/EventQueue_stub.cpp

@@ -60,7 +60,7 @@ void EventQueue::background(Callback<void(int)> update)
 {
 }
 
-void EventQueue::chain(EventQueue *target)
+int EventQueue::chain(EventQueue *target)
 {
 }
 

UNITTESTS/stubs/equeue_stub.c

@@ -103,7 +103,7 @@ void equeue_background(equeue_t *queue,
 
 }
 
-void equeue_chain(equeue_t *queue, equeue_t *target)
+int equeue_chain(equeue_t *queue, equeue_t *target)
 {
 
 }

events/EventQueue.cpp

@@ -71,12 +71,12 @@ void EventQueue::background(Callback<void(int)> update)
     }
 }
 
-void EventQueue::chain(EventQueue *target)
+int EventQueue::chain(EventQueue *target)
 {
     if (target) {
-        equeue_chain(&_equeue, &target->_equeue);
+        return equeue_chain(&_equeue, &target->_equeue);
     } else {
-        equeue_chain(&_equeue, 0);
+        return equeue_chain(&_equeue, 0);
     }
 }
 }

events/EventQueue.h

@@ -181,8 +181,11 @@ class EventQueue : private mbed::NonCopyable<EventQueue> {
      *
      *  @param target   Queue that will dispatch this queue's events as a
      *                  part of its dispatch loop
+     *
+     *  @return Zero on success and negative error code value if chaining fails
+     *
      */
-    void chain(EventQueue *target);
+    int chain(EventQueue *target);
 
 
 

events/equeue/equeue.c

@@ -603,23 +603,27 @@ static void equeue_chain_update(void *p, int ms)
     if (ms >= 0) {
         c->id = equeue_call_in(c->target, ms, equeue_chain_dispatch, c->q);
     } else {
-        equeue_dealloc(c->target, c);
+        equeue_dealloc(c->q, c);
     }
 }
 
-void equeue_chain(equeue_t *q, equeue_t *target)
+int equeue_chain(equeue_t *q, equeue_t *target)
 {
     if (!target) {
         equeue_background(q, 0, 0);
-        return;
+        return 0;
     }
 
     struct equeue_chain_context *c = equeue_alloc(q,
                                                   sizeof(struct equeue_chain_context));
+    if (!c) {
+        return -1;
+    }
 
     c->q = q;
     c->target = target;
     c->id = 0;
 
     equeue_background(q, equeue_chain_update, c);
+    return 0;
 }

events/equeue/equeue.h

@@ -220,7 +220,10 @@ void equeue_background(equeue_t *queue,
 //
 // The equeue_chain function allows multiple equeues to be composed, sharing
 // the context of a dispatch loop while still being managed independently.
-void equeue_chain(equeue_t *queue, equeue_t *target);
+//
+// If the event queue chaining fails, equeue_chain returns a negative,
+// platform-specific error code.
+int equeue_chain(equeue_t *queue, equeue_t *target);
 
 
 #ifdef __cplusplus