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      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 REMOTING_HOST_NATIVE_MESSAGING_NATIVE_MESSAGING_READER_H_
      6 #define REMOTING_HOST_NATIVE_MESSAGING_NATIVE_MESSAGING_READER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/callback.h"
     10 #include "base/files/file.h"
     11 #include "base/memory/scoped_ptr.h"
     12 #include "base/memory/weak_ptr.h"
     13 #include "base/threading/thread.h"
     14 
     15 namespace base {
     16 class SequencedTaskRunner;
     17 class Value;
     18 }  // namespace base
     19 
     20 namespace remoting {
     21 
     22 // This class is used for reading messages from the Native Messaging client
     23 // webapp.
     24 class NativeMessagingReader {
     25  public:
     26   typedef base::Callback<void(scoped_ptr<base::Value>)> MessageCallback;
     27 
     28   explicit NativeMessagingReader(base::File file);
     29   ~NativeMessagingReader();
     30 
     31   // Begin reading messages from the Native Messaging client webapp, calling
     32   // |message_callback| for each received message, or |eof_callback| if
     33   // EOF or error is encountered. This method is asynchronous - the callbacks
     34   // will be run on the same thread via PostTask. The caller should be prepared
     35   // for these callbacks to be invoked right up until this object is destroyed.
     36   void Start(MessageCallback message_callback, base::Closure eof_callback);
     37 
     38  private:
     39   class Core;
     40   friend class Core;
     41 
     42   // Wrappers posted to by the read thread to trigger the message and EOF
     43   // callbacks on the caller thread, and have them safely dropped if the reader
     44   // has been deleted before they are processed.
     45   void InvokeMessageCallback(scoped_ptr<base::Value> message);
     46   void InvokeEofCallback();
     47 
     48   // Holds the information that the read thread needs to access, such as the
     49   // File, and the TaskRunner used for posting notifications back to this
     50   // class.
     51   scoped_ptr<Core> core_;
     52 
     53   // Caller-supplied message and end-of-file callbacks.
     54   MessageCallback message_callback_;
     55   base::Closure eof_callback_;
     56 
     57   // Separate thread used to read from the stream without blocking the main
     58   // thread. net::FileStream's async API cannot be used here because, on
     59   // Windows, it requires the file handle to have been opened for overlapped IO.
     60   base::Thread reader_thread_;
     61   scoped_refptr<base::SequencedTaskRunner> read_task_runner_;
     62 
     63   // Allows the reader to be deleted safely even when tasks may be pending on
     64   // it.
     65   base::WeakPtrFactory<NativeMessagingReader> weak_factory_;
     66 
     67   DISALLOW_COPY_AND_ASSIGN(NativeMessagingReader);
     68 };
     69 
     70 }  // namespace remoting
     71 
     72 #endif  // REMOTING_HOST_NATIVE_MESSAGING_NATIVE_MESSAGING_READER_H_
     73