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
12namespace 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//
47class 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  virtual ~AsyncSocketIoHandler();
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  virtual void OnFileCanWriteWithoutBlocking(int socket) OVERRIDE {}
85  virtual 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_
111