From 33cfd9247500c19265c4faa9344098e057f79bb8 Mon Sep 17 00:00:00 2001
From: Simon Duquennoy <simonduq@sics.se>
Date: Tue, 29 Apr 2014 16:25:16 +0200
Subject: [PATCH] RPL MRHOF with ETX: bypass weighted moving average when
 setting a parent's link metric for the first time

---
 core/net/rpl/rpl-dag.c   |  4 ++--
 core/net/rpl/rpl-icmp6.c |  4 ++--
 core/net/rpl/rpl-mrhof.c | 12 ++++++++++--
 core/net/rpl/rpl.c       |  4 ++--
 core/net/rpl/rpl.h       |  5 ++++-
 5 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/core/net/rpl/rpl-dag.c b/core/net/rpl/rpl-dag.c
index 08178d5ad..d79a7f465 100644
--- a/core/net/rpl/rpl-dag.c
+++ b/core/net/rpl/rpl-dag.c
@@ -1082,8 +1082,8 @@ rpl_recalculate_ranks(void)
    */
   p = nbr_table_head(rpl_parents);
   while(p != NULL) {
-    if(p->dag != NULL && p->dag->instance && p->updated) {
-      p->updated = 0;
+    if(p->dag != NULL && p->dag->instance && (p->flags & RPL_PARENT_FLAG_UPDATED)) {
+      p->flags &= ~RPL_PARENT_FLAG_UPDATED;
       PRINTF("RPL: rpl_process_parent_event recalculate_ranks\n");
       if(!rpl_process_parent_event(p->dag->instance, p)) {
         PRINTF("RPL: A parent was dropped\n");
diff --git a/core/net/rpl/rpl-icmp6.c b/core/net/rpl/rpl-icmp6.c
index b744f4dc8..34ad696d5 100644
--- a/core/net/rpl/rpl-icmp6.c
+++ b/core/net/rpl/rpl-icmp6.c
@@ -652,7 +652,7 @@ dao_input(void)
       PRINTF("RPL: Loop detected when receiving a unicast DAO from a node with a lower rank! (%u < %u)\n",
           DAG_RANK(parent->rank, instance), DAG_RANK(dag->rank, instance));
       parent->rank = INFINITE_RANK;
-      parent->updated = 1;
+      parent->flags |= RPL_PARENT_FLAG_UPDATED;
       return;
     }
 
@@ -660,7 +660,7 @@ dao_input(void)
     if(parent != NULL && parent == dag->preferred_parent) {
       PRINTF("RPL: Loop detected when receiving a unicast DAO from our parent\n");
       parent->rank = INFINITE_RANK;
-      parent->updated = 1;
+      parent->flags |= RPL_PARENT_FLAG_UPDATED;
       return;
     }
   }
diff --git a/core/net/rpl/rpl-mrhof.c b/core/net/rpl/rpl-mrhof.c
index 634bec763..508d66f1d 100644
--- a/core/net/rpl/rpl-mrhof.c
+++ b/core/net/rpl/rpl-mrhof.c
@@ -122,8 +122,16 @@ neighbor_link_callback(rpl_parent_t *p, int status, int numtx)
       packet_etx = MAX_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
     }
 
-    new_etx = ((uint32_t)recorded_etx * ETX_ALPHA +
-               (uint32_t)packet_etx * (ETX_SCALE - ETX_ALPHA)) / ETX_SCALE;
+    if(p->flags & RPL_PARENT_FLAG_LINK_METRIC_VALID) {
+      /* We already have a valid link metric, use weighted moving average to update it */
+      new_etx = ((uint32_t)recorded_etx * ETX_ALPHA +
+                 (uint32_t)packet_etx * (ETX_SCALE - ETX_ALPHA)) / ETX_SCALE;
+    } else {
+      /* We don't have a valid link metric, set it to the current packet's ETX */
+      new_etx = packet_etx;
+      /* Set link metric as valid */
+      p->flags |= RPL_PARENT_FLAG_LINK_METRIC_VALID;
+    }
 
     PRINTF("RPL: ETX changed from %u to %u (packet ETX = %u)\n",
         (unsigned)(recorded_etx / RPL_DAG_MC_ETX_DIVISOR),
diff --git a/core/net/rpl/rpl.c b/core/net/rpl/rpl.c
index fd532c4c6..860131a10 100644
--- a/core/net/rpl/rpl.c
+++ b/core/net/rpl/rpl.c
@@ -260,7 +260,7 @@ rpl_link_neighbor_callback(const linkaddr_t *addr, int status, int numtx)
       if(parent != NULL) {
         /* Trigger DAG rank recalculation. */
         PRINTF("RPL: rpl_link_neighbor_callback triggering update\n");
-        parent->updated = 1;
+        parent->flags |= RPL_PARENT_FLAG_UPDATED;
         if(instance->of->neighbor_link_callback != NULL) {
           instance->of->neighbor_link_callback(parent, status, numtx);
         }
@@ -286,7 +286,7 @@ rpl_ipv6_neighbor_callback(uip_ds6_nbr_t *nbr)
         p->rank = INFINITE_RANK;
         /* Trigger DAG rank recalculation. */
         PRINTF("RPL: rpl_ipv6_neighbor_callback infinite rank\n");
-        p->updated = 1;
+        p->flags |= RPL_PARENT_FLAG_UPDATED;
       }
     }
   }
diff --git a/core/net/rpl/rpl.h b/core/net/rpl/rpl.h
index 76134e44e..c5e89c61b 100644
--- a/core/net/rpl/rpl.h
+++ b/core/net/rpl/rpl.h
@@ -104,6 +104,9 @@ typedef struct rpl_metric_container rpl_metric_container_t;
 struct rpl_instance;
 struct rpl_dag;
 /*---------------------------------------------------------------------------*/
+#define RPL_PARENT_FLAG_UPDATED           0x1
+#define RPL_PARENT_FLAG_LINK_METRIC_VALID 0x2
+
 struct rpl_parent {
   struct rpl_parent *next;
   struct rpl_dag *dag;
@@ -113,7 +116,7 @@ struct rpl_parent {
   rpl_rank_t rank;
   uint16_t link_metric;
   uint8_t dtsn;
-  uint8_t updated;
+  uint8_t flags;
 };
 typedef struct rpl_parent rpl_parent_t;
 /*---------------------------------------------------------------------------*/