components/drive/local_file_reader.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 COMPONENTS_DRIVE_LOCAL_FILE_READER_H_
   6 #define COMPONENTS_DRIVE_LOCAL_FILE_READER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/weak_ptr.h"
  11 #include "net/base/completion_callback.h"
  12 #include "net/base/file_stream.h"
  13
  14 namespace base {
  15 class FilePath;
  16 class SequencedTaskRunner;
  17 }  // namespace base
  18
  19 namespace net {
  20 class IOBuffer;
  21 }  // namespace net
  22
  23 namespace drive {
  24 namespace util {
  25
  26 // This is simple local file reader implementation focusing on Drive's use
  27 // case. All the operations run on |sequenced_task_runner| asynchronously and
  28 // the result will be notified to the caller via |callback|s on the caller's
  29 // thread.
  30 class LocalFileReader {
  31  public:
  32   explicit LocalFileReader(base::SequencedTaskRunner* sequenced_task_runner);
  33   ~LocalFileReader();
  34
  35   // Opens the file at |file_path|. The initial position of the read will be
  36   // at |offset| from the beginning of the file.
  37   // Upon completion, |callback| will be called.
  38   // |callback| must not be null.
  39   void Open(const base::FilePath& file_path,
  40             int64 offset,
  41             const net::CompletionCallback& callback);
  42
  43   // Reads the file and copies the data into |buffer|. |buffer_length|
  44   // is the length of |buffer|.
  45   // Upon completion, |callback| will be called with the result.
  46   // |callback| must not be null.
  47   void Read(net::IOBuffer* buffer,
  48             int buffer_length,
  49             const net::CompletionCallback& callback);
  50
  51  private:
  52   void DidOpen(const net::CompletionCallback& callback,
  53                int64 offset,
  54                int error);
  55   void DidSeek(const net::CompletionCallback& callback,
  56                int64 offset,
  57                int64 error);
  58
  59   net::FileStream file_stream_;
  60
  61   // Note: This should remain the last member so it'll be destroyed and
  62   // invalidate the weak pointers before any other members are destroyed.
  63   base::WeakPtrFactory<LocalFileReader> weak_ptr_factory_;
  64   DISALLOW_COPY_AND_ASSIGN(LocalFileReader);
  65 };
  66
  67 }  // namespace util
  68 }  // namespace drive
  69
  70 #endif  // COMPONENTS_DRIVE_LOCAL_FILE_READER_H_