Enables PacketGenerator's use of PacketCreator's FEC primitives.

net/quic/quic_packet_generator.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_packet_generator.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "net/quic/quic_fec_group.h"
 #include "net/quic/quic_utils.h"
 
 using base::StringPiece;
 
 namespace net {
 
 class QuicAckNotifier;
 
 QuicPacketGenerator::QuicPacketGenerator(DelegateInterface* delegate,
                                          DebugDelegate* debug_delegate,
                                          QuicPacketCreator* creator)
     : delegate_(delegate),
       debug_delegate_(debug_delegate),
       packet_creator_(creator),
       batch_mode_(false),
+      should_fec_protect_(false),
       should_send_ack_(false),
       should_send_feedback_(false),
       should_send_stop_waiting_(false) {
 }
 
 QuicPacketGenerator::~QuicPacketGenerator() {
   for (QuicFrames::iterator it = queued_control_frames_.begin();
        it != queued_control_frames_.end(); ++it) {
     switch (it->type) {
       case PADDING_FRAME:
@@ skipping 101 matching lines @@
     }
 
     if (data.Empty()) {
       // We're done writing the data. Exit the loop.
       // We don't make this a precondition because we could have 0 bytes of data
       // if we're simply writing a fin.
       break;
     }
   }
 
-  // Ensure the FEC group is closed at the end of this method if not in batch
-  // mode.
-  if (!InBatchMode() && packet_creator_->ShouldSendFec(true)) {
-    // TODO(jri): SerializeFec can return a NULL packet, and this should
-    // cause an early return, with a call to delegate_->OnPacketGenerationError.
-    SerializedPacket serialized_fec = packet_creator_->SerializeFec();
-    DCHECK(serialized_fec.packet);
-    delegate_->OnSerializedPacket(serialized_fec);
-  }
+  // Try to close FEC group since we've either run out of data to send or we're
+  // blocked. If not in batch mode, force close the group.
+  MaybeSendFecPacketAndCloseGroup(!InBatchMode());
 
   DCHECK(InBatchMode() || !packet_creator_->HasPendingFrames());
   return QuicConsumedData(total_bytes_consumed, fin_consumed);
 }
 
 bool QuicPacketGenerator::CanSendWithNextPendingFrameAddition() const {
   DCHECK(HasPendingFrames());
   HasRetransmittableData retransmittable =
       (should_send_ack_ || should_send_feedback_ || should_send_stop_waiting_)
       ? NO_RETRANSMITTABLE_DATA : HAS_RETRANSMITTABLE_DATA;
@@ skipping 11 matching lines @@
     if (!AddNextPendingFrame()) {
       // Packet was full, so serialize and send it.
       SerializeAndSendPacket();
     }
   }
 
   if (!InBatchMode() || flush) {
     if (packet_creator_->HasPendingFrames()) {
       SerializeAndSendPacket();
     }
-
     // Ensure the FEC group is closed at the end of this method unless other
     // writes are pending.
-    if (packet_creator_->ShouldSendFec(true)) {
-      // TODO(jri): SerializeFec can return a NULL packet, and this should
-      // cause an early return, with a call to
-      // delegate_->OnPacketGenerationError.
-      SerializedPacket serialized_fec = packet_creator_->SerializeFec();
-      DCHECK(serialized_fec.packet);
-      delegate_->OnSerializedPacket(serialized_fec);
-    }
+    MaybeSendFecPacketAndCloseGroup(true);
   }
 }
 
+void QuicPacketGenerator::MaybeStartFecProtection() {
+  if (!packet_creator_->IsFecEnabled()) {
+    return;
+  }
+  DVLOG(1) << "Turning FEC protection ON";
+  should_fec_protect_ = true;
+  if (packet_creator_->IsFecProtected()) {
+    // Only start creator's FEC protection if not already on.
+    return;
+  }
+  if (HasQueuedFrames()) {
+    // TODO(jri): This currently requires that the generator flush out any
+    // pending frames when FEC protection is turned on. If current packet can be
+    // converted to an FEC protected packet, do it. This will require the
+    // generator to check if the resulting expansion still allows the incoming
+    // frame to be added to the packet.
+    SendQueuedFrames(true);
+  }
+  packet_creator_->StartFecProtectingPackets();
+  DCHECK(packet_creator_->IsFecProtected());
+}
+
+void QuicPacketGenerator::MaybeStopFecProtection(bool force) {
+  DVLOG(1) << "Turning FEC protection OFF";
+  // FEC protection will stop after the next FEC packet is transmitted.
+  should_fec_protect_ = false;
+  MaybeSendFecPacketAndCloseGroup(force);
+}
+
+void QuicPacketGenerator::MaybeSendFecPacketAndCloseGroup(bool force) {
+  if (!packet_creator_->IsFecProtected() ||
+      packet_creator_->HasPendingFrames()) {
+    return;
+  }
+
+  if (packet_creator_->ShouldSendFec(force)) {
+    // TODO(jri): SerializeFec can return a NULL packet, and this should
+    // cause an early return, with a call to
+    // delegate_->OnPacketGenerationError.
+    SerializedPacket serialized_fec = packet_creator_->SerializeFec();
+    DCHECK(serialized_fec.packet);
+    delegate_->OnSerializedPacket(serialized_fec);
+  }
+
+  // Turn FEC protection off if the creator does not have an FEC group open.
+  // Note: We only wait until the frames queued in the creator are flushed;
+  // pending frames in the generator will not keep us from turning FEC off.
+  if (!should_fec_protect_ && !packet_creator_->IsFecGroupOpen()) {
+    packet_creator_->StopFecProtectingPackets();
+    DCHECK(!packet_creator_->IsFecProtected());
+  }
+}
+
 bool QuicPacketGenerator::InBatchMode() {
   return batch_mode_;
 }
 
 void QuicPacketGenerator::StartBatchOperations() {
   batch_mode_ = true;
 }
 
 void QuicPacketGenerator::FinishBatchOperations() {
   batch_mode_ = false;
@@ skipping 57 matching lines @@
   if (success && debug_delegate_) {
     debug_delegate_->OnFrameAddedToPacket(frame);
   }
   return success;
 }
 
 void QuicPacketGenerator::SerializeAndSendPacket() {
   SerializedPacket serialized_packet = packet_creator_->SerializePacket();
   DCHECK(serialized_packet.packet);
   delegate_->OnSerializedPacket(serialized_packet);
-
-  if (packet_creator_->ShouldSendFec(false)) {
-    // TODO(jri): SerializeFec can return a NULL packet, and this should
-    // cause an early return, with a call to delegate_->OnPacketGenerationError.
-    SerializedPacket serialized_fec = packet_creator_->SerializeFec();
-    DCHECK(serialized_fec.packet);
-    delegate_->OnSerializedPacket(serialized_fec);
-  }
+  MaybeSendFecPacketAndCloseGroup(false);
 }
 
 }  // namespace net