Increase the stun ping interval.

webrtc/p2p/base/p2ptransportchannel.cc

Index: webrtc/p2p/base/p2ptransportchannel.cc
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index 206113c4ebcc554d9b401e716c5031412eda4845..4b7b2571478b66b932d8ebe544281fe64eb3068f 100644
--- a/webrtc/p2p/base/p2ptransportchannel.cc
+++ b/webrtc/p2p/base/p2ptransportchannel.cc
@@ -217,10 +217,8 @@ static const int STRONG_PING_INTERVAL = 1000 * PING_PACKET_SIZE / 1000;
 // writable or not receiving.
 const int WEAK_PING_INTERVAL = 1000 * PING_PACKET_SIZE / 10000;
 
-// If the current best connection is both writable and receiving, then we will
-// also try hard to make sure it is pinged at this rate (a little less than
-// 2 * STRONG_PING_INTERVAL).
-static const int MAX_CURRENT_STRONG_INTERVAL = 900;  // ms
+// Writable connections are pinged at a slower rate.
+static const int WRITABLE_CONNECTION_PING_INTERVAL = 2500;  // ms
 
 static const int MIN_CHECK_RECEIVING_INTERVAL = 50;  // ms
 
@@ -250,7 +248,7 @@ P2PTransportChannel::P2PTransportChannel(const std::string& transport_name,
               0 /* backup_connection_ping_interval */,
               false /* gather_continually */,
               false /* prioritize_most_likely_candidate_pairs */,
-              MAX_CURRENT_STRONG_INTERVAL /* max_strong_interval */) {
+              WRITABLE_CONNECTION_PING_INTERVAL /* max_strong_interval */) {

[pthatcher1, 2016/05/06 23:34:38]

The comment doesn't match.  And the comment provides no value.  Perhaps just
delete it.

   uint32_t weak_ping_interval = ::strtoul(
       webrtc::field_trial::FindFullName("WebRTC-StunInterPacketDelay").c_str(),
       nullptr, 10);
@@ -436,11 +434,13 @@ void P2PTransportChannel::SetIceConfig(const IceConfig& config) {
   LOG(LS_INFO) << "Set ping most likely connection to "
                << config_.prioritize_most_likely_candidate_pairs;
 
-  if (config.max_strong_interval >= 0 &&
-      config_.max_strong_interval != config.max_strong_interval) {
-    config_.max_strong_interval = config.max_strong_interval;
-    LOG(LS_INFO) << "Set max strong interval to "
-                 << config_.max_strong_interval;
+  if (config.writable_connection_ping_interval >= 0 &&
+      config_.writable_connection_ping_interval !=
+          config.writable_connection_ping_interval) {
+    config_.writable_connection_ping_interval =
+        config.writable_connection_ping_interval;
+    LOG(LS_INFO) << "Set writable_connection_ping_interval to "
+                 << config_.writable_connection_ping_interval;
   }
 }
 
@@ -1291,6 +1291,7 @@ void P2PTransportChannel::OnCheckAndPing() {
       MarkConnectionPinged(conn);
     }
   }
+
   int delay = std::min(ping_interval, check_receiving_interval_);
   thread()->PostDelayed(delay, this, MSG_CHECK_AND_PING);
 }
@@ -1332,6 +1333,13 @@ bool P2PTransportChannel::IsPingable(Connection* conn, int64_t now) {
     return (now >= conn->last_ping_response_received() +
                        config_.backup_connection_ping_interval);
   }
+
+  // Writable connections are pinged at a slower rate.
+  if (conn->writable()) {
+    return (now >=
+            conn->last_ping_sent() + config_.writable_connection_ping_interval);
+  }
+
   return conn->active();
 }
 
@@ -1347,7 +1355,8 @@ Connection* P2PTransportChannel::FindNextPingableConnection() {
   Connection* conn_to_ping = nullptr;
   if (best_connection_ && best_connection_->connected() &&
       best_connection_->writable() &&
-      (best_connection_->last_ping_sent() + config_.max_strong_interval <=
+      (best_connection_->last_ping_sent() +
+           config_.writable_connection_ping_interval <=
        now)) {
     conn_to_ping = best_connection_;
   } else {