Add GetInitialCongestionWindowInPackets to SendAlgorithmInterface and its implementations. PiperOrigin-RevId: 980180608

diff --git a/quiche/quic/core/congestion_control/bbr2_sender.cc b/quiche/quic/core/congestion_control/bbr2_sender.cc
index 730a781..f2c946b 100644
--- a/quiche/quic/core/congestion_control/bbr2_sender.cc
+++ b/quiche/quic/core/congestion_control/bbr2_sender.cc

@@ -261,6 +261,10 @@
   }
 }
 
+QuicPacketCount Bbr2Sender::GetInitialCongestionWindowInPackets() const {
+  return initial_cwnd_ / kDefaultTCPMSS;
+}
+
 void Bbr2Sender::SetApplicationDrivenPacingRate(
     QuicBandwidth application_bandwidth_target) {
   QUIC_CODE_COUNT(quic_bbr2_set_app_driven_pacing_rate);

diff --git a/quiche/quic/core/congestion_control/bbr2_sender.h b/quiche/quic/core/congestion_control/bbr2_sender.h
index d73a702..597b64f 100644
--- a/quiche/quic/core/congestion_control/bbr2_sender.h
+++ b/quiche/quic/core/congestion_control/bbr2_sender.h

@@ -52,6 +52,8 @@
   void SetInitialCongestionWindowInPackets(
       QuicPacketCount congestion_window) override;
 
+  QuicPacketCount GetInitialCongestionWindowInPackets() const override;
+
   void SetApplicationDrivenPacingRate(
       QuicBandwidth application_bandwidth_target) override;
 

diff --git a/quiche/quic/core/congestion_control/bbr3_sender.cc b/quiche/quic/core/congestion_control/bbr3_sender.cc
index 4fe8829..916d737 100644
--- a/quiche/quic/core/congestion_control/bbr3_sender.cc
+++ b/quiche/quic/core/congestion_control/bbr3_sender.cc

@@ -246,6 +246,10 @@
   }
 }
 
+QuicPacketCount Bbr3Sender::GetInitialCongestionWindowInPackets() const {
+  return initial_cwnd_ / kDefaultTCPMSS;
+}
+
 void Bbr3Sender::SetApplicationDrivenPacingRate(
     QuicBandwidth application_bandwidth_target) {
   QUIC_CODE_COUNT(quic_bbr2_set_app_driven_pacing_rate);

diff --git a/quiche/quic/core/congestion_control/bbr3_sender.h b/quiche/quic/core/congestion_control/bbr3_sender.h
index ab4243d..b1b60e2 100644
--- a/quiche/quic/core/congestion_control/bbr3_sender.h
+++ b/quiche/quic/core/congestion_control/bbr3_sender.h

@@ -48,6 +48,8 @@
   void SetInitialCongestionWindowInPackets(
       QuicPacketCount congestion_window) override;
 
+  QuicPacketCount GetInitialCongestionWindowInPackets() const override;
+
   void SetApplicationDrivenPacingRate(
       QuicBandwidth application_bandwidth_target) override;
 

diff --git a/quiche/quic/core/congestion_control/bbr_sender.cc b/quiche/quic/core/congestion_control/bbr_sender.cc
index 0178c5b..57b9a5f 100644
--- a/quiche/quic/core/congestion_control/bbr_sender.cc
+++ b/quiche/quic/core/congestion_control/bbr_sender.cc

@@ -162,6 +162,10 @@
   }
 }
 
+QuicPacketCount BbrSender::GetInitialCongestionWindowInPackets() const {
+  return initial_congestion_window_ / kDefaultTCPMSS;
+}
+
 bool BbrSender::InSlowStart() const { return mode_ == STARTUP; }
 
 void BbrSender::OnPacketSent(QuicTime sent_time, QuicByteCount bytes_in_flight,

diff --git a/quiche/quic/core/congestion_control/bbr_sender.h b/quiche/quic/core/congestion_control/bbr_sender.h
index eb887eb..eea3fec 100644
--- a/quiche/quic/core/congestion_control/bbr_sender.h
+++ b/quiche/quic/core/congestion_control/bbr_sender.h

@@ -113,6 +113,7 @@
   void AdjustNetworkParameters(const NetworkParams& params) override;
   void SetInitialCongestionWindowInPackets(
       QuicPacketCount congestion_window) override;
+  QuicPacketCount GetInitialCongestionWindowInPackets() const override;
   void SetApplicationDrivenPacingRate(
       QuicBandwidth /*application_bandwidth_target*/) override {}
   void OnCongestionEvent(bool rtt_updated, QuicByteCount prior_in_flight,

diff --git a/quiche/quic/core/congestion_control/send_algorithm_interface.h b/quiche/quic/core/congestion_control/send_algorithm_interface.h
index 41a4114..ee215dc 100644
--- a/quiche/quic/core/congestion_control/send_algorithm_interface.h
+++ b/quiche/quic/core/congestion_control/send_algorithm_interface.h

@@ -93,6 +93,11 @@
   // if called after the initial congestion window is no longer relevant.
   virtual void SetInitialCongestionWindowInPackets(QuicPacketCount packets) = 0;
 
+  // Returns the initial congestion window in number of packets.
+  // Assumes a packet size of kDefaultTCPMSS (1460 bytes),
+  // not kDefaultMaxPacketSize (1250 bytes) for historical reasons.
+  virtual QuicPacketCount GetInitialCongestionWindowInPackets() const = 0;
+
   // [Experimental] Sets the application driven pacing rate. This is only used
   // by an experimental feature for bbr2_sender.
   virtual void SetApplicationDrivenPacingRate(

diff --git a/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.cc b/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.cc
index 610bce7..e1a562a 100644
--- a/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.cc
+++ b/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.cc

@@ -234,6 +234,11 @@
   congestion_window_ = congestion_window * kDefaultTCPMSS;
 }
 
+QuicPacketCount TcpCubicSenderBytes::GetInitialCongestionWindowInPackets()
+    const {
+  return initial_tcp_congestion_window_ / kDefaultTCPMSS;
+}
+
 void TcpCubicSenderBytes::SetMinCongestionWindowInPackets(
     QuicPacketCount congestion_window) {
   min_congestion_window_ = congestion_window * kDefaultTCPMSS;

diff --git a/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.h b/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.h
index c2150b4..84af2e1 100644
--- a/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.h
+++ b/quiche/quic/core/congestion_control/tcp_cubic_sender_bytes.h

@@ -50,6 +50,7 @@
   void SetNumEmulatedConnections(int num_connections);
   void SetInitialCongestionWindowInPackets(
       QuicPacketCount congestion_window) override;
+  QuicPacketCount GetInitialCongestionWindowInPackets() const override;
   void SetApplicationDrivenPacingRate(
       QuicBandwidth /*application_bandwidth_target*/) override {}
   void OnConnectionMigration() override;

diff --git a/quiche/quic/test_tools/quic_test_utils.h b/quiche/quic/test_tools/quic_test_utils.h
index fd8cbf1..750329c 100644
--- a/quiche/quic/test_tools/quic_test_utils.h
+++ b/quiche/quic/test_tools/quic_test_utils.h

@@ -1235,6 +1235,8 @@
               (const QuicTagVector& connection_options), (override));
   MOCK_METHOD(void, SetInitialCongestionWindowInPackets,
               (QuicPacketCount packets), (override));
+  MOCK_METHOD(QuicPacketCount, GetInitialCongestionWindowInPackets, (),
+              (const, override));
   MOCK_METHOD(void, SetApplicationDrivenPacingRate,
               (QuicBandwidth application_bandwidth_target), (override));
   MOCK_METHOD(void, OnCongestionEvent,