device/serial/data_receiver.h

   1 // Copyright 2014 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 DEVICE_SERIAL_DATA_RECEIVER_H_
   6 #define DEVICE_SERIAL_DATA_RECEIVER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/weak_ptr.h"
  11 #include "device/serial/buffer.h"
  12 #include "device/serial/data_stream.mojom.h"
  13 #include "mojo/public/cpp/system/data_pipe.h"
  14
  15 namespace device {
  16
  17 class AsyncWaiter;
  18
  19 // A DataReceiver receives data from a DataSource.
  20 class DataReceiver : public base::RefCounted<DataReceiver>,
  21                      public serial::DataSourceClient,
  22                      public mojo::ErrorHandler {
  23  public:
  24   typedef base::Callback<void(scoped_ptr<ReadOnlyBuffer>)> ReceiveDataCallback;
  25   typedef base::Callback<void(int32_t error)> ReceiveErrorCallback;
  26
  27   // Constructs a DataReceiver to receive data from |source|, using a data
  28   // pipe with a buffer size of |buffer_size|, with connection errors reported
  29   // as |fatal_error_value|.
  30   DataReceiver(mojo::InterfacePtr<serial::DataSource> source,
  31                uint32_t buffer_size,
  32                int32_t fatal_error_value);
  33
  34   // Begins a receive operation. If this returns true, exactly one of |callback|
  35   // and |error_callback| will eventually be called. If there is already a
  36   // receive in progress or there has been a connection error, this will have no
  37   // effect and return false.
  38   bool Receive(const ReceiveDataCallback& callback,
  39                const ReceiveErrorCallback& error_callback);
  40
  41  private:
  42   class PendingReceive;
  43   struct PendingError;
  44   friend class base::RefCounted<DataReceiver>;
  45
  46   ~DataReceiver() override;
  47
  48   // serial::DataSourceClient override. Invoked by the DataSource to report
  49   // errors.
  50   void OnError(uint32_t bytes_since_last_error, int32_t error) override;
  51
  52   // mojo::ErrorHandler override. Calls ShutDown().
  53   void OnConnectionError() override;
  54
  55   // Invoked by the PendingReceive to report that the user is done with the
  56   // receive buffer, having read |bytes_read| bytes from it.
  57   void Done(uint32_t bytes_read);
  58
  59   // Invoked when |handle_| is ready to read. Unless an error has occurred, this
  60   // calls ReceiveInternal().
  61   void OnDoneWaiting(MojoResult result);
  62
  63   // The implementation of Receive(). If a |pending_error_| is ready to
  64   // dispatch, it does so. Otherwise, this attempts to read from |handle_| and
  65   // dispatches the contents to |pending_receive_|. If |handle_| is not ready,
  66   // |waiter_| is used to wait until it is ready. If an error occurs in reading
  67   // |handle_|, ShutDown() is called.
  68   void ReceiveInternal();
  69
  70   // We may have been notified of an error that occurred at some future point in
  71   // the stream. We should never be able to read past the point at which the
  72   // error occurred until we have dealt with the error and called Resume() on
  73   // the DataSource. If this has occurred, something bad has happened on the
  74   // service side, so we shut down.
  75   bool CheckErrorNotInReadRange(uint32_t num_bytes);
  76
  77   // Called when we encounter a fatal error. If a receive is in progress,
  78   // |fatal_error_value_| will be reported to the user.
  79   void ShutDown();
  80
  81   // The control connection to the data source.
  82   mojo::InterfacePtr<serial::DataSource> source_;
  83
  84   // The data connection to the data source.
  85   mojo::ScopedDataPipeConsumerHandle handle_;
  86
  87   // The error value to report in the event of a fatal error.
  88   const int32_t fatal_error_value_;
  89
  90   // The number of bytes received from the data source.
  91   uint32_t bytes_received_;
  92
  93   // Whether we have encountered a fatal error and shut down.
  94   bool shut_down_;
  95
  96   // A waiter used to wait until |handle_| is readable if we are waiting.
  97   scoped_ptr<AsyncWaiter> waiter_;
  98
  99   // The current pending receive operation if there is one.
 100   scoped_ptr<PendingReceive> pending_receive_;
 101
 102   // The current pending error if there is one.
 103   scoped_ptr<PendingError> pending_error_;
 104
 105   base::WeakPtrFactory<DataReceiver> weak_factory_;
 106
 107   DISALLOW_COPY_AND_ASSIGN(DataReceiver);
 108 };
 109
 110 }  // namespace device
 111
 112 #endif  // DEVICE_SERIAL_DATA_RECEIVER_H_