Adds TCP FastOpen blackhole recovery code to avoid getting persistently blackholed.

net/socket/tcp_socket_libevent.h

 // Copyright 2013 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.
 
 #ifndef NET_SOCKET_TCP_SOCKET_LIBEVENT_H_
 #define NET_SOCKET_TCP_SOCKET_LIBEVENT_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ skipping 70 matching lines @@
   //
   // TODO(yzshen): Change logging format and let TCPClientSocket log the
   // start/end of a series of connect attempts itself.
   void StartLoggingMultipleConnectAttempts(const AddressList& addresses);
   void EndLoggingMultipleConnectAttempts(int net_error);
 
   const BoundNetLog& net_log() const { return net_log_; }
 
  private:
   // States that a fast open socket attempt can result in.
-  enum FastOpenStatus {
+  enum TCPFastOpenStatus {
     FAST_OPEN_STATUS_UNKNOWN,
 
     // The initial fast open connect attempted returned synchronously,
     // indicating that we had and sent a cookie along with the initial data.
     FAST_OPEN_FAST_CONNECT_RETURN,
 
     // The initial fast open connect attempted returned asynchronously,
     // indicating that we did not have a cookie for the server.
     FAST_OPEN_SLOW_CONNECT_RETURN,
 
     // Some other error occurred on connection, so we couldn't tell if
     // fast open would have worked.
     FAST_OPEN_ERROR,
 
+    // The initial fast open connect succeeded immediately
+    // (FAST_OPEN_FAST_CONNECT_RETURN) and the attempt to write SYN+DATA failed.
+    FAST_OPEN_FAST_CONNECT_FAILED,
+
+    // The initial fast open connect failed (FAST_OPEN_SLOW_CONNECT_RETURN)
+    // and the first attempt to write data failed.
+    FAST_OPEN_SLOW_CONNECT_FAILED,
+
     // An attempt to do a fast open succeeded immediately
     // (FAST_OPEN_FAST_CONNECT_RETURN) and we later confirmed that the server
     // had acked the data we sent.
     FAST_OPEN_SYN_DATA_ACK,
 
     // An attempt to do a fast open succeeded immediately
     // (FAST_OPEN_FAST_CONNECT_RETURN) and we later confirmed that the server
     // had nacked the data we sent.
     FAST_OPEN_SYN_DATA_NACK,
 
@@ skipping 35 matching lines @@
   void LogConnectBegin(const AddressList& addresses) const;
   void LogConnectEnd(int net_error) const;
 
   void ReadCompleted(const scoped_refptr<IOBuffer>& buf,
                      const CompletionCallback& callback,
                      int rv);
   int HandleReadCompleted(IOBuffer* buf, int rv);
 
   void WriteCompleted(const scoped_refptr<IOBuffer>& buf,
                       const CompletionCallback& callback,
-                      int rv) const;
-  int HandleWriteCompleted(IOBuffer* buf, int rv) const;
+                      int rv);
+  int HandleWriteCompleted(IOBuffer* buf, int rv);
   int TcpFastOpenWrite(IOBuffer* buf,
                        int buf_len,
                        const CompletionCallback& callback);
 
   // Called when the socket is known to be in a connected state.
-  void RecordFastOpenStatus();
+  void RecordTCPFastOpenStatus();
 
   scoped_ptr<SocketLibevent> socket_;
   scoped_ptr<SocketLibevent> accept_socket_;
 
   // Enables experimental TCP FastOpen option.
   bool use_tcp_fastopen_;
-
+  // True when TCP FastOpen is in use and we have attempted the
+  // connect with write.
+  bool tcp_fastopen_write_attempted_;

[Randy Smith (Not in Mondays), 2014/09/22 16:05:13]

nit, suggestion: I'm used to a blank line before comments.

[Jana, 2014/09/22 17:04:56]

Done.

   // True when TCP FastOpen is in use and we have done the connect.
   bool tcp_fastopen_connected_;
-  FastOpenStatus fast_open_status_;
+  TCPFastOpenStatus tcp_fastopen_status_;
 
   bool logging_multiple_connect_attempts_;
 
   BoundNetLog net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(TCPSocketLibevent);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_TCP_SOCKET_LIBEVENT_H_