implement #3295: only transmit background traffic if there is excess bandwidth

4 files changed, 98 insertions, 16 deletions

diff --git a/src/core/gnunet-service-core_neighbours.c b/src/core/gnunet-service-core_neighbours.c
index ddca0859a..aa5b6121e 100644
--- a/src/core/gnunet-service-core_neighbours.c
+++ b/src/core/gnunet-service-core_neighbours.c
@@ -105,6 +105,11 @@ struct Neighbour
    */
   GNUNET_SCHEDULER_TaskIdentifier retry_plaintext_task;
 
+  /**
+   * #GNUNET_YES if this peer currently has excess bandwidth.
+   */
+  int has_excess_bandwidth;
+
 };
 
 
@@ -213,13 +218,13 @@ transmit_ready (void *cls, size_t size, void *buf)
 
   n->th = NULL;
   m = n->message_head;
-  if (m == NULL)
+  if (NULL == m)
   {
     GNUNET_break (0);
     return 0;
   }
   GNUNET_CONTAINER_DLL_remove (n->message_head, n->message_tail, m);
-  if (buf == NULL)
+  if (NULL == buf)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                 "Transmission of message of type %u and size %u failed\n",
@@ -240,6 +245,7 @@ transmit_ready (void *cls, size_t size, void *buf)
               ntohs (((struct GNUNET_MessageHeader *) &m[1])->type),
               (unsigned int) ret, GNUNET_i2s (&n->peer));
   GNUNET_free (m);
+  n->has_excess_bandwidth = GNUNET_NO;
   process_queue (n);
   GNUNET_STATISTICS_update (GSC_stats,
                             gettext_noop
@@ -450,6 +456,54 @@ GSC_NEIGHBOURS_transmit (const struct GNUNET_PeerIdentity *target,
 
 
 /**
+ * One of our neighbours has excess bandwidth,
+ * remember this.
+ *
+ * @param cls NULL
+ * @param pid identity of the peer with excess bandwidth
+ */
+static void
+handle_transport_notify_excess_bw (void *cls,
+                                   const struct GNUNET_PeerIdentity *pid)
+{
+  struct Neighbour *n;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Peer %s has excess bandwidth available\n",
+              GNUNET_i2s (pid));
+  n = find_neighbour (pid);
+  if (NULL == n)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  n->has_excess_bandwidth = GNUNET_YES;
+  GSC_SESSIONS_solicit (pid);
+}
+
+
+/**
+ * Check if the given neighbour has excess bandwidth available.
+ *
+ * @param target neighbour to check
+ * @return #GNUNET_YES if excess bandwidth is available, #GNUNET_NO if not
+ */
+int
+GSC_NEIGHBOURS_check_excess_bandwidth (const struct GNUNET_PeerIdentity *target)
+{
+  struct Neighbour *n;
+
+  n = find_neighbour (target);
+  if (NULL == n)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return n->has_excess_bandwidth;
+}
+
+
+/**
  * Initialize neighbours subsystem.
  */
 int
@@ -457,10 +511,11 @@ GSC_NEIGHBOURS_init ()
 {
   neighbours = GNUNET_CONTAINER_multipeermap_create (128, GNUNET_NO);
   transport =
-      GNUNET_TRANSPORT_connect (GSC_cfg, &GSC_my_identity, NULL,
-                                &handle_transport_receive,
-                                &handle_transport_notify_connect,
-                                &handle_transport_notify_disconnect);
+      GNUNET_TRANSPORT_connect2 (GSC_cfg, &GSC_my_identity, NULL,
+                                 &handle_transport_receive,
+                                 &handle_transport_notify_connect,
+                                 &handle_transport_notify_disconnect,
+                                 &handle_transport_notify_excess_bw);
   if (NULL == transport)
   {
     GNUNET_CONTAINER_multipeermap_destroy (neighbours);
diff --git a/src/core/gnunet-service-core_neighbours.h b/src/core/gnunet-service-core_neighbours.h
index d613c46a5..8dcd20634 100644
--- a/src/core/gnunet-service-core_neighbours.h
+++ b/src/core/gnunet-service-core_neighbours.h
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)
+     (C) 2009-2014 Christian Grothoff (and other contributing authors)
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -47,6 +47,16 @@ GSC_NEIGHBOURS_transmit (const struct GNUNET_PeerIdentity *target,
 
 
 /**
+ * Check if the given neighbour has excess bandwidth available.
+ *
+ * @param target neighbour to check
+ * @return #GNUNET_YES if excess bandwidth is available, #GNUNET_NO if not
+ */
+int
+GSC_NEIGHBOURS_check_excess_bandwidth (const struct GNUNET_PeerIdentity *target);
+
+
+/**
  * Initialize neighbours subsystem.
  */
 int
diff --git a/src/core/gnunet-service-core_sessions.c b/src/core/gnunet-service-core_sessions.c
index 080bbf88b..4e0ef5e30 100644
--- a/src/core/gnunet-service-core_sessions.c
+++ b/src/core/gnunet-service-core_sessions.c
@@ -508,13 +508,20 @@ try_transmission (struct Session *session)
   enum GNUNET_CORE_Priority maxp;
   enum GNUNET_CORE_Priority maxpc;
   struct GSC_ClientActiveRequest *car;
+  int excess;
 
   if (GNUNET_YES != session->ready_to_transmit)
     return;
   msize = 0;
   min_deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
-  /* check 'ready' messages */
-  maxp = GNUNET_CORE_PRIO_BACKGROUND;
+  /* if the peer has excess bandwidth, background traffic is allowed,
+     otherwise not */
+  excess = GSC_NEIGHBOURS_check_excess_bandwidth (&session->peer);
+  if (GNUNET_YES == excess)
+    maxp = GNUNET_CORE_PRIO_BACKGROUND;
+  else
+    maxp = GNUNET_CORE_PRIO_BEST_EFFORT;
+  /* determine highest priority of 'ready' messages we already solicited from clients */
   pos = session->sme_head;
   while ((NULL != pos) &&
          (msize + pos->size <= GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE))
@@ -527,7 +534,12 @@ try_transmission (struct Session *session)
   }
   if (maxp < GNUNET_CORE_PRIO_CRITICAL_CONTROL)
   {
-    maxpc = GNUNET_CORE_PRIO_BACKGROUND;
+    /* if highest already solicited priority from clients is not critical,
+       check if there are higher-priority messages to be solicited from clients */
+    if (GNUNET_YES == excess)
+      maxpc = GNUNET_CORE_PRIO_BACKGROUND;
+    else
+      maxpc = GNUNET_CORE_PRIO_BEST_EFFORT;
     for (car = session->active_client_request_head; NULL != car; car = car->next)
     {
       if (GNUNET_YES == car->was_solicited)
@@ -545,11 +557,15 @@ try_transmission (struct Session *session)
   }
 
   now = GNUNET_TIME_absolute_get ();
-  if ((0 == msize) ||
-      ((msize < GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE / 2) &&
-       (min_deadline.abs_value_us > now.abs_value_us)))
+  if ( ( (GNUNET_YES == excess) ||
+         (maxpc >= GNUNET_CORE_PRIO_BEST_EFFORT) ) &&
+       ( (0 == msize) ||
+         ( (msize < GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE / 2) &&
+           (min_deadline.abs_value_us > now.abs_value_us))) )
   {
-    /* not enough ready yet, try to solicit more */
+    /* not enough ready yet (tiny message & cork possible), or no messages at all,
+       and either excess bandwidth or best-effort or higher message waiting at
+       client; in this case, we try to solicit more */
     solicit_messages (session,
                       msize);
     if (msize > 0)
@@ -565,7 +581,8 @@ try_transmission (struct Session *session)
     }
     return;
   }
-  /* create plaintext buffer of all messages, encrypt and transmit */
+  /* create plaintext buffer of all messages (that fit), encrypt and
+     transmit */
   {
     static unsigned long long total_bytes;
     static unsigned int total_msgs;
diff --git a/src/core/gnunet-service-core_sessions.h b/src/core/gnunet-service-core_sessions.h
index cc88548ec..034026bb8 100644
--- a/src/core/gnunet-service-core_sessions.h
+++ b/src/core/gnunet-service-core_sessions.h
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)
+     (C) 2009-2014 Christian Grothoff (and other contributing authors)
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published