Reland of Add experiment on weak ping delay during call set up time

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.
  */
 
 #include "webrtc/p2p/base/p2ptransportchannel.h"
 
 #include <algorithm>
 #include <set>
 #include "webrtc/p2p/base/common.h"
 #include "webrtc/p2p/base/relayport.h"  // For RELAY_PORT_TYPE.
 #include "webrtc/p2p/base/stunport.h"  // For STUN_PORT_TYPE.
 #include "webrtc/base/common.h"
 #include "webrtc/base/crc32.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/stringencode.h"
+#include "webrtc/system_wrappers/interface/field_trial.h"
 
 namespace {
 
 // messages for queuing up work for ourselves
 enum { MSG_SORT = 1, MSG_CHECK_AND_PING };
 
-// When the socket is unwritable, we will use 10 Kbps (ignoring IP+UDP headers)
-// for pinging.  When the socket is writable, we will use only 1 Kbps because
-// we don't want to degrade the quality on a modem.  These numbers should work
-// well on a 28.8K modem, which is the slowest connection on which the voice
-// quality is reasonable at all.
-static const uint32_t PING_PACKET_SIZE = 60 * 8;
-// STRONG_PING_DELAY (480ms) is applied when the best connection is both
-// writable and receiving.
-static const uint32_t STRONG_PING_DELAY = 1000 * PING_PACKET_SIZE / 1000;
-// WEAK_PING_DELAY (48ms) is applied when the best connection is either not
-// writable or not receiving.
-static const uint32_t WEAK_PING_DELAY = 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_DELAY).
-static const uint32_t MAX_CURRENT_STRONG_DELAY = 900;
-
-static const int MIN_CHECK_RECEIVING_DELAY = 50;  // ms
-
 // The minimum improvement in RTT that justifies a switch.
 static const double kMinImprovement = 10;
 
 cricket::PortInterface::CandidateOrigin GetOrigin(cricket::PortInterface* port,
                                          cricket::PortInterface* origin_port) {
   if (!origin_port)
     return cricket::PortInterface::ORIGIN_MESSAGE;
   else if (port == origin_port)
     return cricket::PortInterface::ORIGIN_THIS_PORT;
   else
@@ skipping 135 matching lines @@
     return prefs_cmp < 0;
   }
 
   return b_conn->rtt() <= a_conn->rtt() + kMinImprovement;
 }
 
 }  // unnamed namespace
 
 namespace cricket {
 
+// When the socket is unwritable, we will use 10 Kbps (ignoring IP+UDP headers)
+// for pinging.  When the socket is writable, we will use only 1 Kbps because
+// we don't want to degrade the quality on a modem.  These numbers should work
+// well on a 28.8K modem, which is the slowest connection on which the voice
+// quality is reasonable at all.
+static const uint32_t PING_PACKET_SIZE = 60 * 8;
+// STRONG_PING_DELAY (480ms) is applied when the best connection is both
+// writable and receiving.
+static const uint32_t STRONG_PING_DELAY = 1000 * PING_PACKET_SIZE / 1000;
+// WEAK_PING_DELAY (48ms) is applied when the best connection is either not
+// writable or not receiving.
+const uint32_t WEAK_PING_DELAY = 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_DELAY).
+static const uint32_t MAX_CURRENT_STRONG_DELAY = 900;
+
+static const int MIN_CHECK_RECEIVING_DELAY = 50;  // ms
+
+
 P2PTransportChannel::P2PTransportChannel(const std::string& transport_name,
                                          int component,
                                          P2PTransport* transport,
                                          PortAllocator* allocator)
     : TransportChannelImpl(transport_name, component),
       transport_(transport),
       allocator_(allocator),
       worker_thread_(rtc::Thread::Current()),
       incoming_only_(false),
       error_(0),
       best_connection_(NULL),
       pending_best_connection_(NULL),
       sort_dirty_(false),
       was_writable_(false),
       remote_ice_mode_(ICEMODE_FULL),
       ice_role_(ICEROLE_UNKNOWN),
       tiebreaker_(0),
       remote_candidate_generation_(0),
       gathering_state_(kIceGatheringNew),
       check_receiving_delay_(MIN_CHECK_RECEIVING_DELAY * 5),
-      receiving_timeout_(MIN_CHECK_RECEIVING_DELAY * 50) {}
+      receiving_timeout_(MIN_CHECK_RECEIVING_DELAY * 50) {
+  uint32_t weak_ping_delay = ::strtoul(
+      webrtc::field_trial::FindFullName("WebRTC-StunInterPacketDelay").c_str(),
+      nullptr, 10);
+  if (weak_ping_delay) {
+    weak_ping_delay_ =  weak_ping_delay;
+  }
+}
 
 P2PTransportChannel::~P2PTransportChannel() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
 
   for (size_t i = 0; i < allocator_sessions_.size(); ++i)
     delete allocator_sessions_[i];
 }
 
 // Add the allocator session to our list so that we know which sessions
 // are still active.
@@ skipping 916 matching lines @@
   SortConnections();
 }
 
 // Handle queued up check-and-ping request
 void P2PTransportChannel::OnCheckAndPing() {
   // Make sure the states of the connections are up-to-date (since this affects
   // which ones are pingable).
   UpdateConnectionStates();
   // When the best connection is either not receiving or not writable,
   // switch to weak ping delay.
-  int ping_delay = weak() ? WEAK_PING_DELAY : STRONG_PING_DELAY;
+  int ping_delay = weak() ? weak_ping_delay_ : STRONG_PING_DELAY;
   if (rtc::Time() >= last_ping_sent_ms_ + ping_delay) {
     Connection* conn = FindNextPingableConnection();
     if (conn) {
       PingConnection(conn);
     }
   }
   int check_delay = std::min(ping_delay, check_receiving_delay_);
   thread()->PostDelayed(check_delay, this, MSG_CHECK_AND_PING);
 }
 
@@ skipping 193 matching lines @@
   SignalSentPacket(this, sent_packet);
 }
 
 void P2PTransportChannel::OnReadyToSend(Connection* connection) {
   if (connection == best_connection_ && writable()) {
     SignalReadyToSend(this);
   }
 }
 
 }  // namespace cricket