From e59aabf0eb8ce56d3414254ab9c7b6cc90dd05c3 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Wed, 18 Jul 2012 12:26:34 +0000
Subject: [PATCH] -trying to fix high CPU load caused by DHT

---
 src/dht/gnunet-service-dht_routing.c | 58 ++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 3 deletions(-)

diff --git a/src/dht/gnunet-service-dht_routing.c b/src/dht/gnunet-service-dht_routing.c
index c1dca4e21..796991b5b 100644
--- a/src/dht/gnunet-service-dht_routing.c
+++ b/src/dht/gnunet-service-dht_routing.c
@@ -322,6 +322,48 @@ expire_oldest_entry ()
 }
 
 
+/**
+ * Try to combine multiple recent requests for the same value
+ * (if they come from the same peer).
+ *
+ * @param cls the new 'struct RecentRequest' (to discard upon successful combination)
+ * @param key the query
+ * @param value the existing 'struct RecentRequest' (to update upon successful combination)
+ * @return GNUNET_OK (continue to iterate),
+ *         GNUNET_SYSERR if the request was successfully combined
+ */
+static int
+try_combine_recent (void *cls, const struct GNUNET_HashCode * key, void *value)
+{
+  struct RecentRequest *in = cls;
+  struct RecentRequest *rr = value;
+
+  if ( (0 != memcmp (&in->peer,
+		     &rr->peer,
+		     sizeof (struct GNUNET_PeerIdentity))) ||
+       (in->type != rr->type) ||
+       (in->xquery_size != rr->xquery_size) ||
+       (0 != memcmp (in->xquery,
+		     rr->xquery,
+		     in->xquery_size)) )
+    return GNUNET_OK;
+  if (in->reply_bf_mutator != rr->reply_bf_mutator)
+  {
+    rr->reply_bf_mutator = in->reply_bf_mutator;
+    GNUNET_CONTAINER_bloomfilter_free (rr->reply_bf);
+    rr->reply_bf = in->reply_bf;
+  }
+  else
+  {
+    GNUNET_CONTAINER_bloomfilter_or2 (rr->reply_bf,
+				      in->reply_bf,
+				      GNUNET_CONTAINER_bloomfilter_get_size (in->reply_bf));
+    GNUNET_CONTAINER_bloomfilter_free (in->reply_bf);
+  }
+  GNUNET_free (in);
+  return GNUNET_SYSERR;
+}
+
 
 /**
  * Add a new entry to our routing table.
@@ -354,15 +396,25 @@ GDS_ROUTING_add (const struct GNUNET_PeerIdentity *sender,
   recent_req = GNUNET_malloc (sizeof (struct RecentRequest) + xquery_size);
   recent_req->peer = *sender;
   recent_req->key = *key;
-  recent_req->heap_node =
-      GNUNET_CONTAINER_heap_insert (recent_heap, recent_req,
-                                    GNUNET_TIME_absolute_get ().abs_value);
   recent_req->reply_bf = GNUNET_CONTAINER_bloomfilter_copy (reply_bf);
   recent_req->type = type;
   recent_req->options = options;
   recent_req->xquery = &recent_req[1];
   recent_req->xquery_size = xquery_size;
   recent_req->reply_bf_mutator = reply_bf_mutator;
+  if (GNUNET_SYSERR ==
+      GNUNET_CONTAINER_multihashmap_get_multiple (recent_map, key,
+						  &try_combine_recent, recent_req))
+  {
+    GNUNET_STATISTICS_update (GDS_stats,
+                              gettext_noop
+                              ("# DHT requests combined"),
+                              1, GNUNET_NO);
+    return;
+  }
+  recent_req->heap_node =
+      GNUNET_CONTAINER_heap_insert (recent_heap, recent_req,
+                                    GNUNET_TIME_absolute_get ().abs_value);
   GNUNET_CONTAINER_multihashmap_put (recent_map, key, recent_req,
                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
 
-- 
2.25.1