Adds dynamic FEC on/off switch in packet creator. Tightens use of

net/quic/quic_packet_creator.h

 // 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.
 //
 // Accumulates frames for the next packet until more frames no longer fit or
 // it's time to create a packet from them.  Also provides packet creation of
 // FEC packets based on previously created packets.
 
 #ifndef NET_QUIC_QUIC_PACKET_CREATOR_H_
 #define NET_QUIC_QUIC_PACKET_CREATOR_H_
@@ skipping 39 matching lines @@
                     QuicFramer* framer,
                     QuicRandom* random_generator,
                     bool is_server);
 
   virtual ~QuicPacketCreator();
 
   // QuicFecBuilderInterface
   virtual void OnBuiltFecProtectedPayload(const QuicPacketHeader& header,
                                           base::StringPiece payload) OVERRIDE;
 
+  // Turn on FEC protection for subsequently created packets. FEC should
+  // be enabled first (set_max_packets_per_fec_group should be non-zero) for
+  // FEC protection to start.
+  void StartFecProtectingPackets();
+
+  // Turn off FEC protection for subsequently created packets. If the creator
+  // has any open fec group, call will fail. It is the caller's responsibility
+  // to flush out FEC packets in generation, and to verify with ShouldSendFec()
+  // that there is no open FEC group.
+  void StopFecProtectingPackets();
+
   // Checks if it's time to send an FEC packet.  |force_close| forces this to
   // return true if an fec group is open.
   bool ShouldSendFec(bool force_close) const;
 
+  // Returns current max number of packets covered by an FEC group.
+  size_t max_packets_per_fec_group() const;
+
+  // Sets creator's max number of packets covered by an FEC group.
+  void set_max_packets_per_fec_group(size_t max_packets_per_fec_group);
+
   // Makes the framer not serialize the protocol version in sent packets.
   void StopSendingVersion();
 
   // Update the sequence number length to use in future packets as soon as it
   // can be safely changed.
   void UpdateSequenceNumberLength(
       QuicPacketSequenceNumber least_packet_awaited_by_peer,
       QuicByteCount congestion_window);
 
   // The overhead the framing will add for a packet with one frame.
@@ skipping 28 matching lines @@
                                        QuicFrame* frame);
 
   // Serializes all frames into a single packet. All frames must fit into a
   // single packet. Also, sets the entropy hash of the serialized packet to a
   // random bool and returns that value as a member of SerializedPacket.
   // Never returns a RetransmittableFrames in SerializedPacket.
   SerializedPacket SerializeAllFrames(const QuicFrames& frames);
 
   // Re-serializes frames with the original packet's sequence number length.
   // Used for retransmitting packets to ensure they aren't too long.
+  // Caller must ensure that any open FEC group are closed before calling this
+  // method.
   SerializedPacket ReserializeAllFrames(
       const QuicFrames& frames, QuicSequenceNumberLength original_length);
 
   // Returns true if there are frames pending to be serialized.
   bool HasPendingFrames();
 
-  // Returns IN_FEC_GROUP or NOT_IN_FEC_GROUP, depending on whether FEC is
-  // enabled or not. Note: This does not mean that an FEC group is currently
-  // active; i.e., fec_group_.get() may still be NULL.
-  // TODO(jri): Straighten out naming: Enabling FEC for the connection
-  // should use FEC_ENABLED/DISABLED, and IN_FEC_GROUP/NOT_IN_FEC_GROUP should
-  // be used if a given packet is in an fec group.
-  InFecGroup IsFecEnabled() const;
+  // Returns whether FEC protection is currently enabled. Note: Enabled does not
+  // mean that an FEC group is currently active; i.e., IsFecProtected() may
+  // still return NOT_IN_FEC_GROUP, and fec_group_.get() may still be NULL.
+  bool IsFecEnabled() const;
+
+  // Returns true if subsequent packets will be FEC protected. Note: True does
+  // not mean that an FEC packet is currently under construction; i.e.,
+  // fec_group_.get() may still be NULL, until MaybeStartFec() is called.
+  bool IsFecProtected() const;
 
   // Returns the number of bytes which are available to be used by additional
   // frames in the packet.  Since stream frames are slightly smaller when they
   // are the last frame in a packet, this method will return a different
   // value than max_packet_size - PacketSize(), in this case.
   size_t BytesFree() const;
 
   // Returns the number of bytes that the packet will expand by if a new frame
   // is added to the packet. If the last frame was a stream frame, it will
   // expand slightly when a new frame is added, and this method returns the
@@ skipping 60 matching lines @@
     return &options_;
   }
 
  private:
   friend class test::QuicPacketCreatorPeer;
 
   static bool ShouldRetransmit(const QuicFrame& frame);
 
   // Starts a new FEC group with the next serialized packet, if FEC is enabled
   // and there is not already an FEC group open.
-  InFecGroup MaybeStartFEC();
+  InFecGroup MaybeStartFec();
 
   void FillPacketHeader(QuicFecGroupNumber fec_group,
                         bool fec_flag,
                         QuicPacketHeader* header);
 
   // Allows a frame to be added without creating retransmittable frames.
   // Particularly useful for retransmits using SerializeAllFrames().
   bool AddFrame(const QuicFrame& frame, bool save_retransmittable_frames);
 
   // Adds a padding frame to the current packet only if the current packet
   // contains a handshake message, and there is sufficient room to fit a
   // padding frame.
   void MaybeAddPadding();
 
   Options options_;
   QuicConnectionId connection_id_;
   EncryptionLevel encryption_level_;
   QuicFramer* framer_;
   scoped_ptr<QuicRandomBoolSource> random_bool_source_;
   QuicPacketSequenceNumber sequence_number_;
+  // If true, any created packets will be FEC protected.
+  bool should_fec_protect_;
   QuicFecGroupNumber fec_group_number_;
   scoped_ptr<QuicFecGroup> fec_group_;
   // bool to keep track if this packet creator is being used the server.
   bool is_server_;
   // Controls whether protocol version should be included while serializing the
   // packet.
   bool send_version_in_packet_;
   // The sequence number length for the current packet and the current FEC group
   // if FEC is enabled.
   // Mutable so PacketSize() can adjust it when the packet is empty.
   mutable QuicSequenceNumberLength sequence_number_length_;
   // packet_size_ is mutable because it's just a cache of the current size.
   // packet_size should never be read directly, use PacketSize() instead.
   mutable size_t packet_size_;
   QuicFrames queued_frames_;
   scoped_ptr<RetransmittableFrames> queued_retransmittable_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicPacketCreator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_CREATOR_H_