[GNUnet-SVN] r10969 - in gnunet: . src/topology

[gnunet]

Author: grothoff
Date: 2010-04-18 00:54:36 +0200 (Sun, 18 Apr 2010)
New Revision: 10969

Modified:
   gnunet/TODO
   gnunet/src/topology/gnunet-daemon-topology.c
Log:
use back-off and higher-frequency re-tries to start with for creating 
connections

Modified: gnunet/TODO
===================================================================
--- gnunet/TODO 2010-04-17 21:16:41 UTC (rev 10968)
+++ gnunet/TODO 2010-04-17 22:54:36 UTC (rev 10969)
@@ -3,12 +3,6 @@
   - trust: need *fast* way to check/update trust in peers
            (async peerinfo would not be right; certainly not with the current 
API)
 * TOPOLOGY: [CG]
-  - needs to re-try connecting after disconnect (currently, it
-    initially triggers a connection request, but if that connection
-    fails / goes down, it does not retry in a timely fashion;
-    cause seems to be the 'greylist_after_attempt' being set to 1h,
-    which is rather long -- and should probably be adjusted based on
-    the number of connections / known peers & use some form of back-off)
   - If the topology daemon crashes, peers that were put on the
     blacklist with transport will never be removed from it (until
     transport service dies); we should use the blacklist notification

Modified: gnunet/src/topology/gnunet-daemon-topology.c
===================================================================
--- gnunet/src/topology/gnunet-daemon-topology.c        2010-04-17 21:16:41 UTC 
(rev 10968)
+++ gnunet/src/topology/gnunet-daemon-topology.c        2010-04-17 22:54:36 UTC 
(rev 10969)
@@ -41,15 +41,27 @@
  * For how long do we blacklist a peer after a failed connection
  * attempt?
  */
-#define GREYLIST_AFTER_ATTEMPT GNUNET_TIME_UNIT_HOURS
+#define GREYLIST_AFTER_ATTEMPT GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_MINUTES, 15)
 
 /**
  * For how long do we blacklist a friend after a failed connection
  * attempt?
  */
-#define GREYLIST_AFTER_ATTEMPT_FRIEND GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_MINUTES, 15)
+#define GREYLIST_AFTER_ATTEMPT_FRIEND GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_MINUTES, 2)
 
 /**
+ * For how long do we blacklist anyone under any cirumstances after a failed 
connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT_MIN GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_SECONDS, 15)
+
+/**
+ * For how long do we blacklist anyone under any cirumstances after a failed 
connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT_MAX GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_HOURS, 18)
+
+/**
  * How often do we at most advertise any HELLO to a peer?
  */
 #define HELLO_ADVERTISEMENT_MIN_FREQUENCY GNUNET_TIME_relative_multiply 
(GNUNET_TIME_UNIT_HOURS, 4)
@@ -127,6 +139,11 @@
   GNUNET_SCHEDULER_TaskIdentifier greylist_clean_task;
 
   /**
+   * How often have we tried so far?
+   */
+  unsigned int connect_attempts;
+
+  /**
    * Is this peer listed here because he is a friend?
    */
   int is_friend;
@@ -512,7 +529,15 @@
     rem = GREYLIST_AFTER_ATTEMPT_FRIEND;
   else
     rem = GREYLIST_AFTER_ATTEMPT;
-  /* FIXME: do exponential back-off? */
+  rem = GNUNET_TIME_relative_multiply (rem, connection_count);
+  rem = GNUNET_TIME_relative_divide (rem, target_connection_count);
+  if (pos->connect_attempts > 30)
+    pos->connect_attempts = 30;
+  rem = GNUNET_TIME_relative_multiply (rem, 1 << (++pos->connect_attempts));
+  rem = GNUNET_TIME_relative_max (rem,
+                                 GREYLIST_AFTER_ATTEMPT_MIN);
+  rem = GNUNET_TIME_relative_min (rem,
+                                 GREYLIST_AFTER_ATTEMPT_MAX);
   pos->greylisted_until = GNUNET_TIME_relative_to_absolute (rem);
   if (pos->greylist_clean_task != GNUNET_SCHEDULER_NO_TASK)
     GNUNET_SCHEDULER_cancel (sched,
@@ -857,6 +882,7 @@
       pos->greylisted_until.value = 0; /* remove greylisting */
     }
   pos->is_connected = GNUNET_YES;
+  pos->connect_attempts = 0; /* re-set back-off factor */
   if (pos->is_friend)
     {
       if ( (friend_count == minimum_friend_count - 1) &&