Increase the stun ping interval.

webrtc/p2p/base/p2ptransportchannel.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 199 matching lines @@
 // well on a 28.8K modem, which is the slowest connection on which the voice
 // quality is reasonable at all.
 static const int PING_PACKET_SIZE = 60 * 8;
 // STRONG_PING_INTERVAL (480ms) is applied when the best connection is both
 // writable and receiving.
 static const int STRONG_PING_INTERVAL = 1000 * PING_PACKET_SIZE / 1000;
 // WEAK_PING_INTERVAL (48ms) is applied when the best connection is either not
 // 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 faster rate while stabilizing.
+static const int STABLIZING_WRITABLE_CONNECTION_PING_INTERVAL = 900;  // ms
+
+// Writable connections are pinged at a slower rate once stablized.
+static const int STABLE_WRITABLE_CONNECTION_PING_INTERVAL = 2500;  // ms
 
 static const int MIN_CHECK_RECEIVING_INTERVAL = 50;  // ms
 
 P2PTransportChannel::P2PTransportChannel(const std::string& transport_name,
                                          int component,
                                          P2PTransport* transport,
                                          PortAllocator* allocator)
     : P2PTransportChannel(transport_name, component, allocator) {}
 
 P2PTransportChannel::P2PTransportChannel(const std::string& transport_name,
                                          int component,
                                          PortAllocator* allocator)
     : TransportChannelImpl(transport_name, component),
       allocator_(allocator),
       worker_thread_(rtc::Thread::Current()),
       incoming_only_(false),
       error_(0),
       best_connection_(NULL),
       pending_best_connection_(NULL),
       sort_dirty_(false),
       remote_ice_mode_(ICEMODE_FULL),
       ice_role_(ICEROLE_UNKNOWN),
       tiebreaker_(0),
       gathering_state_(kIceGatheringNew),
       check_receiving_interval_(MIN_CHECK_RECEIVING_INTERVAL * 5),
       config_(MIN_CHECK_RECEIVING_INTERVAL * 50 /* receiving_timeout */,
               0 /* backup_connection_ping_interval */,
               false /* gather_continually */,
               false /* prioritize_most_likely_candidate_pairs */,
-              MAX_CURRENT_STRONG_INTERVAL /* max_strong_interval */) {
+              STABLE_WRITABLE_CONNECTION_PING_INTERVAL) {
   uint32_t weak_ping_interval = ::strtoul(
       webrtc::field_trial::FindFullName("WebRTC-StunInterPacketDelay").c_str(),
       nullptr, 10);
   if (weak_ping_interval) {
     weak_ping_interval_ = static_cast<int>(weak_ping_interval);
   }
 }
 
 P2PTransportChannel::~P2PTransportChannel() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
@@ skipping 161 matching lines @@
     }
     LOG(LS_INFO) << "Set ICE receiving timeout to " << config_.receiving_timeout
                  << " milliseconds";
   }
 
   config_.prioritize_most_likely_candidate_pairs =
       config.prioritize_most_likely_candidate_pairs;
   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.stable_writable_connection_ping_interval >= 0 &&
+      config_.stable_writable_connection_ping_interval !=
+          config.stable_writable_connection_ping_interval) {
+    config_.stable_writable_connection_ping_interval =
+        config.stable_writable_connection_ping_interval;
+    LOG(LS_INFO) << "Set stable_writable_connection_ping_interval to "
+                 << config_.stable_writable_connection_ping_interval;
   }
 }
 
 const IceConfig& P2PTransportChannel::config() const {
   return config_;
 }
 
 // Go into the state of processing candidates, and running in general
 void P2PTransportChannel::Connect() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
@@ skipping 924 matching lines @@
   if (weak()) {
     return true;
   }
 
   // Always ping active connections regardless whether the channel is completed
   // or not, but backup connections are pinged at a slower rate.
   if (IsBackupConnection(conn)) {
     return (now >= conn->last_ping_response_received() +
                        config_.backup_connection_ping_interval);
   }
-  return conn->active();
+
+  // Don't ping inactive non-backup connections.
+  if (!conn->active()) {
+    return false;
+  }
+
+  // Do ping unwritable, active connections.
+  if (!conn->writable()) {
+    return true;
+  }
+
+  // Each connection ping sufficiently.
+  if (conn->num_pings_sent() <= MIN_PINGS_AT_WEAK_PING_INTERVAL) {
+    return true;
+  }
+
+  // Ping writable, active connections if it's been long enough since the last
+  // ping.
+  int ping_interval = config_.stable_writable_connection_ping_interval;
+  // A stablized connection gets a slower ping rate.
+  // A connection is stablized if and only if:
+  // 1. Has sent enough initial pings for RTT to converge.
+  // 2. Is receiving ping response.
+  bool stable = conn->num_pings_sent() > MIN_PINGS_TO_STABILIZE &&
+                (conn->pings_since_last_response().size() == 0 ||
+                 now <= conn->last_ping_response_received() +
+                            STABLIZING_WRITABLE_CONNECTION_PING_INTERVAL);
+  if (!stable) {
+    ping_interval =
+        std::min(ping_interval, STABLIZING_WRITABLE_CONNECTION_PING_INTERVAL);
+  }
+  return (now >= conn->last_ping_sent() + ping_interval);
+}
+
+bool P2PTransportChannel::IsBestConnectionPingable() {
+  if (!best_connection_ || !best_connection_->connected() ||
+      !best_connection_->writable()) {
+    return false;
+  }
+
+  int interval =
+      best_connection_->num_pings_sent() <= MIN_PINGS_TO_STABILIZE
+          ? std::min(STABLE_WRITABLE_CONNECTION_PING_INTERVAL,
+                     config_.stable_writable_connection_ping_interval)

[honghaiz3, 2016/06/03 22:54:07]

Should this be the same as the ping_interval calculation above?

[Zhi Huang, 2016/06/03 23:56:22]

Yes, it should be.

+          : config_.stable_writable_connection_ping_interval;
+  return best_connection_->last_ping_sent() + interval <= rtc::TimeMillis();

[honghaiz3, 2016/06/03 22:54:07]

You could pass in now from the parameter to avoid reading the clock again. 
Probably better to use a common method to calculate the ping interval and decide
IsPingable to avoid the code duplicate. 

[Zhi Huang, 2016/06/03 23:56:22]

Done.

 }
 
 // Returns the next pingable connection to ping.  This will be the oldest
 // pingable connection unless we have a connected, writable connection that is
-// past the maximum acceptable ping interval. When reconnecting a TCP
+// past the writable ping interval. When reconnecting a TCP
 // connection, the best connection is disconnected, although still WRITABLE
 // while reconnecting. The newly created connection should be selected as the
 // ping target to become writable instead. See the big comment in
 // CompareConnections.
 Connection* P2PTransportChannel::FindNextPingableConnection() {
   int64_t now = rtc::TimeMillis();
   Connection* conn_to_ping = nullptr;
-  if (best_connection_ && best_connection_->connected() &&
-      best_connection_->writable() &&
-      (best_connection_->last_ping_sent() + config_.max_strong_interval <=
-       now)) {
+  if (IsBestConnectionPingable()) {
     conn_to_ping = best_connection_;
   } else {
     conn_to_ping = FindConnectionToPing(now);
   }
   return conn_to_ping;
 }
 
 void P2PTransportChannel::MarkConnectionPinged(Connection* conn) {
   if (conn && pinged_connections_.insert(conn).second) {
     unpinged_connections_.erase(conn);
@@ skipping 277 matching lines @@
 
   // During the initial state when nothing has been pinged yet, return the first
   // one in the ordered |connections_|.
   return *(std::find_if(connections_.begin(), connections_.end(),
                         [conn1, conn2](Connection* conn) {
                           return conn == conn1 || conn == conn2;
                         }));
 }
 
 }  // namespace cricket