towards adding mq destruction notification

[oweals/gnunet.git] / src / util / mq.c

diff --git a/src/util/mq.c b/src/util/mq.c
index b971fdefd95214787d73a127c3fa5c978bc8b548..01cdf764b90aa9c4e8b285d5015c92e256155c95 100644 (file)
--- a/src/util/mq.c
+++ b/src/util/mq.c
@@ -154,6 +154,16 @@ struct GNUNET_MQ_Handle
    */
   struct GNUNET_SCHEDULER_Task *continue_task;
 
+  /**
+   * Functions to call on queue destruction; kept in a DLL.
+   */
+  struct GNUNET_MQ_DestroyNotificationHandle *dnh_head;
+
+  /**
+   * Functions to call on queue destruction; kept in a DLL.
+   */
+  struct GNUNET_MQ_DestroyNotificationHandle *dnh_tail;
+
   /**
    * Additional options buffer set for this queue by
    * #GNUNET_MQ_set_options().  Default is 0.
@@ -359,6 +369,7 @@ GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
   GNUNET_assert (NULL != mq);
   GNUNET_assert (NULL == ev->parent_queue);
 
+  mq->queue_length++;
   ev->parent_queue = mq;
   /* is the implementation busy? queue it! */
   if (NULL != mq->current_envelope)
@@ -366,11 +377,12 @@ GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
     GNUNET_CONTAINER_DLL_insert_tail (mq->envelope_head,
                                       mq->envelope_tail,
                                       ev);
-    mq->queue_length++;
     return;
   }
   mq->current_envelope = ev;
-  mq->send_impl (mq, ev->mh, mq->impl_state);
+  mq->send_impl (mq,
+                ev->mh,
+                mq->impl_state);
 }
 
 
@@ -422,6 +434,8 @@ impl_send_continue (void *cls)
   current_envelope = mq->current_envelope;
   GNUNET_assert (NULL != current_envelope);
   current_envelope->parent_queue = NULL;
+  GNUNET_assert (0 < mq->queue_length);
+  mq->queue_length--;
   if (NULL == mq->envelope_head)
   {
     mq->current_envelope = NULL;
@@ -432,7 +446,6 @@ impl_send_continue (void *cls)
     GNUNET_CONTAINER_DLL_remove (mq->envelope_head,
                                  mq->envelope_tail,
                                  mq->current_envelope);
-    mq->queue_length--;
     mq->send_impl (mq,
                   mq->current_envelope->mh,
                   mq->impl_state);
@@ -973,7 +986,6 @@ GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq)
     mq->queue_length--;
     GNUNET_MQ_discard (ev);
   }
-  GNUNET_assert (0 == mq->queue_length);
   if (NULL != mq->current_envelope)
   {
     /* we can only discard envelopes that
@@ -981,7 +993,9 @@ GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq)
     mq->current_envelope->parent_queue = NULL;
     GNUNET_MQ_discard (mq->current_envelope);
     mq->current_envelope = NULL;
+    mq->queue_length--;
   }
+  GNUNET_assert (0 == mq->queue_length);
   if (NULL != mq->assoc_map)
   {
     GNUNET_CONTAINER_multihashmap32_destroy (mq->assoc_map);
@@ -1039,6 +1053,7 @@ GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev)
   {
     // complex case, we already started with transmitting
     // the message
+    mq->queue_length--;
     mq->cancel_impl (mq,
                     mq->impl_state);
     // continue sending the next message, if any
@@ -1096,7 +1111,10 @@ GNUNET_MQ_get_current_envelope (struct GNUNET_MQ_Handle *mq)
 struct GNUNET_MQ_Envelope *
 GNUNET_MQ_get_last_envelope (struct GNUNET_MQ_Handle *mq)
 {
-  return mq->envelope_tail;
+  if (NULL != mq->envelope_tail)
+    return mq->envelope_tail;
+
+  return mq->current_envelope;
 }
 
 
@@ -1165,4 +1183,81 @@ GNUNET_MQ_set_options (struct GNUNET_MQ_Handle *mq,
 }
 
 
+/**
+ * Handle we return for callbacks registered to be
+ * notified when #GNUNET_MQ_destroy() is called on a queue.
+ */
+struct GNUNET_MQ_DestroyNotificationHandle
+{
+  /**
+   * Kept in a DLL.
+   */
+  struct GNUNET_MQ_DestroyNotificationHandle *prev;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct GNUNET_MQ_DestroyNotificationHandle *next;
+
+  /**
+   * Queue to notify about.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Function to call.
+   */
+  GNUNET_SCHEDULER_TaskCallback cb;
+
+  /**
+   * Closure for @e cb.
+   */
+  void *cb_cls;
+};
+
+
+/**
+ * Register function to be called whenever @a mq is being
+ * destroyed.
+ *
+ * @param mq message queue to watch
+ * @param cb function to call on @a mq destruction
+ * @param cb_cls closure for @a cb
+ * @return handle for #GNUNET_MQ_destroy_notify_cancel().
+ */
+struct GNUNET_MQ_DestroyNotificationHandle *
+GNUNET_MQ_destroy_notify (struct GNUNET_MQ_Handle *mq,
+                         GNUNET_SCHEDULER_TaskCallback cb,
+                         void *cb_cls)
+{
+  struct GNUNET_MQ_DestroyNotificationHandle *dnh;
+
+  dnh = GNUNET_new (struct GNUNET_MQ_DestroyNotificationHandle);
+  dnh->mq = mq;
+  dnh->cb = cb;
+  dnh->cb_cls = cb_cls;
+  GNUNET_CONTAINER_DLL_insert (mq->dnh_head,
+                              mq->dnh_tail,
+                              dnh);
+  return dnh;
+}
+
+
+/**
+ * Cancel registration from #GNUNET_MQ_destroy_notify().
+ *
+ * @param dnh handle for registration to cancel
+ */
+void
+GNUNET_MQ_destroy_notify_cancel (struct GNUNET_MQ_DestroyNotificationHandle *dnh)
+{
+  struct GNUNET_MQ_Handle *mq = dnh->mq;
+  
+  GNUNET_CONTAINER_DLL_remove (mq->dnh_head,
+                              mq->dnh_tail,
+                              dnh);
+  GNUNET_free (dnh);
+}
+
+
 /* end of mq.c */