base/async_socket_io_handler.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_ASYNC_SOCKET_IO_HANDLER_H_
   6 #define BASE_ASYNC_SOCKET_IO_HANDLER_H_
   7
   8 #include "base/message_loop/message_loop.h"
   9 #include "base/sync_socket.h"
  10 #include "base/threading/non_thread_safe.h"
  11
  12 namespace base {
  13
  14 // Extends the CancelableSyncSocket class to allow reading from a socket
  15 // asynchronously on a TYPE_IO message loop thread.  This makes it easy to share
  16 // a thread that uses a message loop (e.g. for IPC and other things) and not
  17 // require a separate thread to read from the socket.
  18 //
  19 // Example usage (also see the unit tests):
  20 //
  21 // class SocketReader {
  22 //  public:
  23 //   SocketReader(base::CancelableSyncSocket* socket)
  24 //       : socket_(socket), buffer_() {
  25 //     io_handler.Initialize(socket_->handle(),
  26 //                           base::Bind(&SocketReader::OnDataAvailable,
  27 //                                      base::Unretained(this));
  28 //   }
  29 //
  30 //   void AsyncRead() {
  31 //     CHECK(io_handler.Read(&buffer_[0], sizeof(buffer_)));
  32 //   }
  33 //
  34 //  private:
  35 //   void OnDataAvailable(int bytes_read) {
  36 //     if (ProcessData(&buffer_[0], bytes_read)) {
  37 //       // Issue another read.
  38 //       CHECK(io_handler.Read(&buffer_[0], sizeof(buffer_)));
  39 //     }
  40 //   }
  41 //
  42 //   base::AsyncSocketIoHandler io_handler;
  43 //   base::CancelableSyncSocket* socket_;
  44 //   char buffer_[kBufferSize];
  45 // };
  46 //
  47 class BASE_EXPORT AsyncSocketIoHandler
  48     : public NON_EXPORTED_BASE(base::NonThreadSafe),
  49 // The message loop callback interface is different based on platforms.
  50 #if defined(OS_WIN)
  51       public NON_EXPORTED_BASE(base::MessageLoopForIO::IOHandler) {
  52 #else
  53       public NON_EXPORTED_BASE(base::MessageLoopForIO::Watcher) {
  54 #endif
  55  public:
  56   AsyncSocketIoHandler();
  57   ~AsyncSocketIoHandler() override;
  58
  59   // Type definition for the callback. The parameter tells how many
  60   // bytes were read and is 0 if an error occurred.
  61   typedef base::Callback<void(int)> ReadCompleteCallback;
  62
  63   // Initializes the AsyncSocketIoHandler by hooking it up to the current
  64   // thread's message loop (must be TYPE_IO), to do async reads from the socket
  65   // on the current thread.  The |callback| will be invoked whenever a Read()
  66   // has completed.
  67   bool Initialize(base::SyncSocket::Handle socket,
  68                   const ReadCompleteCallback& callback);
  69
  70   // Attempts to read from the socket.  The return value will be |false|
  71   // if an error occurred and |true| if data was read or a pending read
  72   // was issued.  Regardless of async or sync operation, the
  73   // ReadCompleteCallback (see above) will be called when data is available.
  74   bool Read(char* buffer, int buffer_len);
  75
  76  private:
  77 #if defined(OS_WIN)
  78   // Implementation of IOHandler on Windows.
  79   virtual void OnIOCompleted(base::MessageLoopForIO::IOContext* context,
  80                              DWORD bytes_transfered,
  81                              DWORD error) override;
  82 #elif defined(OS_POSIX)
  83   // Implementation of base::MessageLoopForIO::Watcher.
  84   void OnFileCanWriteWithoutBlocking(int socket) override {}
  85   void OnFileCanReadWithoutBlocking(int socket) override;
  86
  87   void EnsureWatchingSocket();
  88 #endif
  89
  90   base::SyncSocket::Handle socket_;
  91 #if defined(OS_WIN)
  92   base::MessageLoopForIO::IOContext* context_;
  93   bool is_pending_;
  94 #elif defined(OS_POSIX)
  95   base::MessageLoopForIO::FileDescriptorWatcher socket_watcher_;
  96   // |pending_buffer_| and |pending_buffer_len_| are valid only between
  97   // Read() and OnFileCanReadWithoutBlocking().
  98   char* pending_buffer_;
  99   int pending_buffer_len_;
 100   // |true| iff the message loop is watching the socket for IO events.
 101   bool is_watching_;
 102 #endif
 103   ReadCompleteCallback read_complete_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(AsyncSocketIoHandler);
 106 };
 107
 108 }  // namespace base.
 109
 110 #endif  // BASE_ASYNC_SOCKET_IO_HANDLER_H_