From 63eb0920ef2261e98dc0ff6310c303a5d8c163ce Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Mon, 19 Sep 2016 14:31:14 +0000
Subject: [PATCH] towards adding mq destruction notification

---
 src/include/gnunet_mq_lib.h  | 30 +++++++++++++
 src/nse/gnunet-service-nse.c |  4 +-
 src/util/mq.c                | 87 ++++++++++++++++++++++++++++++++++++
 3 files changed, 119 insertions(+), 2 deletions(-)

diff --git a/src/include/gnunet_mq_lib.h b/src/include/gnunet_mq_lib.h
index 999ee4134..ff8c9ba1b 100644
--- a/src/include/gnunet_mq_lib.h
+++ b/src/include/gnunet_mq_lib.h
@@ -636,6 +636,36 @@ void
 GNUNET_MQ_destroy (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;
+
+
+/**
+ * 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);
+
+/**
+ * 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);
+
+
 /**
  * Call the message message handler that was registered
  * for the type of the given message in the given message queue.
diff --git a/src/nse/gnunet-service-nse.c b/src/nse/gnunet-service-nse.c
index 1f06c0a75..bf7c79fcb 100644
--- a/src/nse/gnunet-service-nse.c
+++ b/src/nse/gnunet-service-nse.c
@@ -276,12 +276,12 @@ static unsigned int estimate_count;
 /**
  * Task scheduled to update our flood message for the next round.
  */
-static struct GNUNET_SCHEDULER_Task * flood_task;
+static struct GNUNET_SCHEDULER_Task *flood_task;
 
 /**
  * Task scheduled to compute our proof.
  */
-static struct GNUNET_SCHEDULER_Task * proof_task;
+static struct GNUNET_SCHEDULER_Task *proof_task;
 
 /**
  * Notification context, simplifies client broadcasts.
diff --git a/src/util/mq.c b/src/util/mq.c
index e9dba3d9d..01cdf764b 100644
--- 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.
@@ -1173,4 +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 */
-- 
2.25.1