Support datagrams in QuicTransport.

gfe-relnote: n/a (no functional change to production code)
PiperOrigin-RevId: 288493541
Change-Id: I6d2a791ae062701ad4b9fb650ab267566373675f

quic/core/quic_datagram_queue.cc

diff --git a/quic/core/quic_datagram_queue.cc b/quic/core/quic_datagram_queue.cc
index d9ed53f..073ee10 100644
--- a/quic/core/quic_datagram_queue.cc
+++ b/quic/core/quic_datagram_queue.cc
@@ -5,6 +5,7 @@
 #include "net/third_party/quiche/src/quic/core/quic_datagram_queue.h"
 
 #include "net/third_party/quiche/src/quic/core/quic_constants.h"
+#include "net/third_party/quiche/src/quic/core/quic_session.h"
 #include "net/third_party/quiche/src/quic/core/quic_time.h"
 #include "net/third_party/quiche/src/quic/core/quic_types.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_mem_slice_span.h"

quic/core/quic_datagram_queue.h

diff --git a/quic/core/quic_datagram_queue.h b/quic/core/quic_datagram_queue.h
index 2cb8576..712a56e 100644
--- a/quic/core/quic_datagram_queue.h
+++ b/quic/core/quic_datagram_queue.h
@@ -5,13 +5,16 @@
 #ifndef QUICHE_QUIC_CORE_QUIC_DATAGRAM_QUEUE_H_
 #define QUICHE_QUIC_CORE_QUIC_DATAGRAM_QUEUE_H_
 
-#include "net/third_party/quiche/src/quic/core/quic_session.h"
 #include "net/third_party/quiche/src/quic/core/quic_time.h"
+#include "net/third_party/quiche/src/quic/core/quic_types.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_containers.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_mem_slice.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_optional.h"
 
 namespace quic {
 
+class QuicSession;
+
 // Provides a way to buffer QUIC datagrams (messages) in case they cannot
 // be sent due to congestion control.  Datagrams are buffered for a limited
 // amount of time, and deleted after that time passes.
@@ -43,6 +46,8 @@
 
   size_t queue_size() { return queue_.size(); }
 
+  bool empty() { return queue_.empty(); }
+
  private:
   struct QUIC_EXPORT_PRIVATE Datagram {
     QuicMemSlice datagram;

quic/core/quic_session.cc

diff --git a/quic/core/quic_session.cc b/quic/core/quic_session.cc
index c5fe37b..55ce02d 100644
--- a/quic/core/quic_session.cc
+++ b/quic/core/quic_session.cc
@@ -94,6 +94,7 @@
       goaway_received_(false),
       control_frame_manager_(this),
       last_message_id_(0),
+      datagram_queue_(this),
       closed_streams_clean_up_alarm_(nullptr),
       supported_versions_(supported_versions),
       use_http2_priority_write_scheduler_(false),
@@ -571,6 +572,7 @@
                           ? write_blocked_streams_.NumBlockedSpecialStreams()
                           : write_blocked_streams_.NumBlockedStreams();
   if (num_writes == 0 && !control_frame_manager_.WillingToWrite() &&
+      datagram_queue_.empty() &&
       (!QuicVersionUsesCryptoFrames(transport_version()) ||
        !GetCryptoStream()->HasBufferedCryptoFrames())) {
     return;
@@ -591,6 +593,15 @@
   if (control_frame_manager_.WillingToWrite()) {
     control_frame_manager_.OnCanWrite();
   }
+  // TODO(b/147146815): this makes all datagrams go before stream data.  We
+  // should have a better priority scheme for this.
+  if (!datagram_queue_.empty()) {
+    size_t written = datagram_queue_.SendDatagrams();
+    QUIC_DVLOG(1) << ENDPOINT << "Sent " << written << " datagrams";
+    if (!datagram_queue_.empty()) {
+      return;
+    }
+  }
   for (size_t i = 0; i < num_writes; ++i) {
     if (!(write_blocked_streams_.HasWriteBlockedSpecialStream() ||
           write_blocked_streams_.HasWriteBlockedDataStreams())) {

quic/core/quic_session.h

diff --git a/quic/core/quic_session.h b/quic/core/quic_session.h
index b818737..f10b548 100644
--- a/quic/core/quic_session.h
+++ b/quic/core/quic_session.h
@@ -19,6 +19,7 @@
 #include "net/third_party/quiche/src/quic/core/quic_connection.h"
 #include "net/third_party/quiche/src/quic/core/quic_control_frame_manager.h"
 #include "net/third_party/quiche/src/quic/core/quic_crypto_stream.h"
+#include "net/third_party/quiche/src/quic/core/quic_datagram_queue.h"
 #include "net/third_party/quiche/src/quic/core/quic_error_codes.h"
 #include "net/third_party/quiche/src/quic/core/quic_packet_creator.h"
 #include "net/third_party/quiche/src/quic/core/quic_packets.h"
@@ -616,6 +617,8 @@
     return stream_id_manager_;
   }
 
+  QuicDatagramQueue* datagram_queue() { return &datagram_queue_; }
+
   // Processes the stream type information of |pending| depending on
   // different kinds of sessions' own rules. Returns true if the pending stream
   // is converted into a normal stream.
@@ -788,6 +791,9 @@
   // Id of latest successfully sent message.
   QuicMessageId last_message_id_;
 
+  // The buffer used to queue the DATAGRAM frames.
+  QuicDatagramQueue datagram_queue_;
+
   // TODO(fayang): switch to linked_hash_set when chromium supports it. The bool
   // is not used here.
   // List of streams with pending retransmissions.