Add Socket::ReadIfReady()

net/socket/tcp_client_socket.h

 // Copyright (c) 2011 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_CLIENT_SOCKET_H_
 #define NET_SOCKET_TCP_CLIENT_SOCKET_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 50 matching lines @@
   bool WasAlpnNegotiated() const override;
   NextProto GetNegotiatedProtocol() const override;
   bool GetSSLInfo(SSLInfo* ssl_info) override;
 
   // Socket implementation.
   // Multiple outstanding requests are not supported.
   // Full duplex mode (reading and writing at the same time) is supported.
   int Read(IOBuffer* buf,
            int buf_len,
            const CompletionCallback& callback) override;
+  int ReadIfReady(IOBuffer* buf,
+                  int buf_len,
+                  const CompletionCallback& callback) override;
   int Write(IOBuffer* buf,
             int buf_len,
             const CompletionCallback& callback) override;
   int SetReceiveBufferSize(int32_t size) override;
   int SetSendBufferSize(int32_t size) override;
 
   virtual bool SetKeepAlive(bool enable, int delay);
   virtual bool SetNoDelay(bool no_delay);
 
   void GetConnectionAttempts(ConnectionAttempts* out) const override;
   void ClearConnectionAttempts() override;
   void AddConnectionAttempts(const ConnectionAttempts& attempts) override;
   int64_t GetTotalReceivedBytes() const override;
 
  private:
   // State machine for connecting the socket.
   enum ConnectState {
     CONNECT_STATE_CONNECT,
     CONNECT_STATE_CONNECT_COMPLETE,
     CONNECT_STATE_NONE,
   };
 
+  // A helper method shared by Read() and ReadIfReady().
+  // If |read_if_ready| is set to true, ReadIfReady() will be used instead of
+  // Read().
+  int ReadCommon(IOBuffer* buf,
+                 int buf_len,
+                 const CompletionCallback& callback,
+                 bool read_if_ready);
+
   // State machine used by Connect().
   int DoConnectLoop(int result);
   int DoConnect();
   int DoConnectComplete(int result);
 
   // Helper used by Disconnect(), which disconnects minus resetting
   // current_address_index_ and bind_address_.
   void DoDisconnect();
 
   void DidCompleteConnect(int result);
@@ skipping 44 matching lines @@
 
   // Total number of bytes received by the socket.
   int64_t total_received_bytes_;
 
   DISALLOW_COPY_AND_ASSIGN(TCPClientSocket);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_TCP_CLIENT_SOCKET_H_