diff --git a/lib/ChangeLog b/lib/ChangeLog
index 4573839..6d1a229 100644
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,11 @@
+2005-02-21 Vincenzo Eramo <eramo at infocom.ing.uniroma1.it>
+
+	* pqueue.[ch]: Introduce "update" function to meet ospf spf needs. It
+	  will allow to update node when:
+	  i) a node is inserted into the priority queue;
+	  ii) a node position is modified in the priority queue;
+	* pqueue.h: Export trickle_down() function.
+
 2005-02-19 Paul Jakma <paul.jakma@sun.com>
 
 	* stream.c: (stream_new) fix dumb mistake.
diff --git a/lib/pqueue.c b/lib/pqueue.c
index 1e41b09..870f8a7 100644
--- a/lib/pqueue.c
+++ b/lib/pqueue.c
@@ -56,14 +56,18 @@
     {
       /* actually trickle up */
       queue->array[index] = queue->array[PARENT_OF (index)];
+      if (queue->update != NULL)
+	(*queue->update) (queue->array[index], index);
       index = PARENT_OF (index);
     }
 
   /* Restore the tmp node to appropriate place.  */
   queue->array[index] = tmp;
+  if (queue->update != NULL)
+    (*queue->update) (tmp, index);
 }
 
-static void
+void
 trickle_down (int index, struct pqueue *queue)
 {
   void *tmp;
@@ -90,11 +94,15 @@
 
       /* Actually trickle down the tmp node.  */
       queue->array[index] = queue->array[which];
+       if (queue->update != NULL)
+	 (*queue->update) (queue->array[index], index);
       index = which;
     }
 
   /* Restore the tmp node to appropriate place.  */
   queue->array[index] = tmp;
+  if (queue->update != NULL)
+    (*queue->update) (tmp, index);
 }
 
 struct pqueue *
@@ -110,6 +118,8 @@
   memset (queue->array, 0, DATA_SIZE * PQUEUE_INIT_ARRAYSIZE);
   queue->array_size = PQUEUE_INIT_ARRAYSIZE;
 
+  /* By default we want nothing to happen when a node changes. */
+  queue->update = NULL;
   return queue;
 }
 
@@ -146,6 +156,8 @@
     return;
 
   queue->array[queue->size] = data;
+  if (queue->update != NULL)
+    (*queue->update) (data, queue->size);
   trickle_up (queue->size, queue);
   queue->size ++;
 }
diff --git a/lib/pqueue.h b/lib/pqueue.h
index 95f79b8..d19c46d 100644
--- a/lib/pqueue.h
+++ b/lib/pqueue.h
@@ -28,6 +28,7 @@
   int size;
 
   int (*cmp) (void *, void *);
+  void (*update) (void * node, int actual_position);
 };
 
 #define PQUEUE_INIT_ARRAYSIZE  32
@@ -38,4 +39,6 @@
 void pqueue_enqueue (void *data, struct pqueue *queue);
 void *pqueue_dequeue (struct pqueue *queue);
 
+void trickle_down (int index, struct pqueue *queue);
+
 #endif /* _ZEBRA_PQUEUE_H */