Prevent busy-looping PacedSender on small packets.

webrtc/modules/pacing/bitrate_prober_unittest.cc

 /*
  *  Copyright (c) 2014 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 <limits>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "webrtc/modules/pacing/bitrate_prober.h"
 
 namespace webrtc {
 
 TEST(BitrateProberTest, VerifyStatesAndTimeBetweenProbes) {
   BitrateProber prober;
   EXPECT_FALSE(prober.IsProbing());
   int64_t now_ms = 0;
   EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
 
   prober.SetEnabled(true);
   EXPECT_FALSE(prober.IsProbing());
 
-  prober.MaybeInitializeProbe(300000);
+  prober.OnIncomingPacket(300000, 1000, now_ms);
   EXPECT_TRUE(prober.IsProbing());
 
+  // First packet should probe as soon as possible.
   EXPECT_EQ(0, prober.TimeUntilNextProbe(now_ms));
   prober.PacketSent(now_ms, 1000);
 
   for (int i = 0; i < 5; ++i) {
     EXPECT_EQ(8, prober.TimeUntilNextProbe(now_ms));
     now_ms += 4;
     EXPECT_EQ(4, prober.TimeUntilNextProbe(now_ms));
     now_ms += 4;
     EXPECT_EQ(0, prober.TimeUntilNextProbe(now_ms));
     prober.PacketSent(now_ms, 1000);
   }
   for (int i = 0; i < 5; ++i) {
     EXPECT_EQ(4, prober.TimeUntilNextProbe(now_ms));
     now_ms += 4;
     EXPECT_EQ(0, prober.TimeUntilNextProbe(now_ms));
     prober.PacketSent(now_ms, 1000);
   }
 
   EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
   EXPECT_FALSE(prober.IsProbing());
 }
+
+TEST(BitrateProberTest, DoesntProbeWithoutRecentPackets) {
+  BitrateProber prober;
+  EXPECT_FALSE(prober.IsProbing());
+  int64_t now_ms = 0;
+  EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
+
+  prober.SetEnabled(true);
+  EXPECT_FALSE(prober.IsProbing());
+
+  prober.OnIncomingPacket(300000, 1000, now_ms);
+  EXPECT_TRUE(prober.IsProbing());
+  EXPECT_EQ(0, prober.TimeUntilNextProbe(now_ms));
+  // Let time pass, no large enough packets put into prober.
+  now_ms += 6000;
+  EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
+  // Insert a small packet, not a candidate for probing.
+  prober.OnIncomingPacket(300000, 100, now_ms);
+  prober.PacketSent(now_ms, 100);
+  EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
+  // Insert a large-enough packet after downtime while probing should reset to
+  // perform a new probe since the requested one didn't finish.
+  prober.OnIncomingPacket(300000, 1000, now_ms);
+  EXPECT_EQ(0, prober.TimeUntilNextProbe(now_ms));
+  prober.PacketSent(now_ms, 1000);
+  // Next packet should be part of new probe and be sent with non-zero delay.
+  prober.OnIncomingPacket(300000, 1000, now_ms);
+  EXPECT_GT(prober.TimeUntilNextProbe(now_ms), 0);
+}
+
+TEST(BitrateProberTest, DoesntInitializeProbingForSmallPackets) {
+  BitrateProber prober;
+  prober.SetEnabled(true);
+  EXPECT_FALSE(prober.IsProbing());
+
+  prober.OnIncomingPacket(300000, 100, 0);
+  EXPECT_FALSE(prober.IsProbing());
+}
+
 }  // namespace webrtc