chrome/browser/chromeos/file_system_provider/fileapi/buffering_file_stream_writer.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 CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_BUFFERING_FILE_STREAM_WRITER_H_
   6 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_BUFFERING_FILE_STREAM_WRITER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "storage/browser/fileapi/file_stream_writer.h"
  13
  14 namespace net {
  15 class IOBuffer;
  16 }  // namespace net
  17
  18 namespace chromeos {
  19 namespace file_system_provider {
  20
  21 // Wraps the file stream writer implementation with an intermediate buffer.
  22 // Writes data from the inner file stream writer in chunks of size at least
  23 // |intermediate_buffer_length| bytes (or less for the last chunk, or when
  24 // Flush() is explicitely called).
  25 //
  26 // The underlying inner file stream writer *must not* return any values
  27 // synchronously. Instead, results must be returned by a callback, including
  28 // errors. Moreover, partial writes are *not* supported.
  29 class BufferingFileStreamWriter : public storage::FileStreamWriter {
  30  public:
  31   BufferingFileStreamWriter(
  32       scoped_ptr<storage::FileStreamWriter> file_stream_writer,
  33       int intermediate_buffer_length);
  34
  35   ~BufferingFileStreamWriter() override;
  36
  37   // storage::FileStreamWriter overrides.
  38   int Write(net::IOBuffer* buf,
  39             int buf_len,
  40             const net::CompletionCallback& callback) override;
  41   int Cancel(const net::CompletionCallback& callback) override;
  42   int Flush(const net::CompletionCallback& callback) override;
  43
  44  private:
  45   // Copies |buffer_length| bytes of data from the |buffer| starting at
  46   // |buffer_offset| position to the current position of the intermediate
  47   // buffer.
  48   void CopyToIntermediateBuffer(scoped_refptr<net::IOBuffer> buffer,
  49                                 int buffer_offset,
  50                                 int buffer_length);
  51
  52   // Flushes all of the bytes in the intermediate buffer to the inner file
  53   // stream writer.
  54   void FlushIntermediateBuffer(const net::CompletionCallback& callback);
  55
  56   // Called when flushing the intermediate buffer is completed with either
  57   // a success or an error.
  58   void OnFlushIntermediateBufferCompleted(
  59       int length,
  60       const net::CompletionCallback& callback,
  61       int result);
  62
  63   // Called when flushing the intermediate buffer for direct write is completed
  64   // with either a success or an error.
  65   void OnFlushIntermediateBufferForDirectWriteCompleted(
  66       scoped_refptr<net::IOBuffer> buffer,
  67       int length,
  68       const net::CompletionCallback& callback,
  69       int result);
  70
  71   // Called when flushing the intermediate buffer for a buffered write is
  72   // completed with either a success or an error.
  73   void OnFlushIntermediateBufferForBufferedWriteCompleted(
  74       scoped_refptr<net::IOBuffer> buffer,
  75       int buffered_bytes,
  76       int bytes_left,
  77       const net::CompletionCallback& callback,
  78       int result);
  79
  80   // Called when flushing the intermediate buffer for a flush call is completed
  81   // with either a success or an error.
  82   void OnFlushIntermediateBufferForFlushCompleted(
  83       const net::CompletionCallback& callback,
  84       int result);
  85
  86   scoped_ptr<storage::FileStreamWriter> file_stream_writer_;
  87   int intermediate_buffer_length_;
  88   scoped_refptr<net::IOBuffer> intermediate_buffer_;
  89   int buffered_bytes_;
  90
  91   base::WeakPtrFactory<BufferingFileStreamWriter> weak_ptr_factory_;
  92   DISALLOW_COPY_AND_ASSIGN(BufferingFileStreamWriter);
  93 };
  94
  95 }  // namespace file_system_provider
  96 }  // namespace chromeos
  97
  98 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_BUFFERING_FILE_STREAM_WRITER_H_