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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 #include "chrome/browser/chromeos/file_system_provider/fileapi/buffering_file_st ream_reader.h" | |
6 | |
7 #include <algorithm> | |
8 | |
9 #include "base/message_loop/message_loop.h" | |
10 #include "net/base/io_buffer.h" | |
11 #include "net/base/net_errors.h" | |
12 | |
13 namespace chromeos { | |
14 namespace file_system_provider { | |
15 | |
16 BufferingFileStreamReader::BufferingFileStreamReader( | |
17 scoped_ptr<webkit_blob::FileStreamReader> file_stream_reader, | |
18 int buffer_size) | |
19 : file_stream_reader_(file_stream_reader.Pass()), | |
20 buffer_size_(buffer_size), | |
21 preloading_buffer_(new net::IOBuffer(buffer_size_)), | |
22 preloading_buffer_offset_(0), | |
23 buffered_bytes_(0), | |
24 weak_ptr_factory_(this) { | |
25 } | |
26 | |
27 BufferingFileStreamReader::~BufferingFileStreamReader() { | |
28 } | |
29 | |
30 int BufferingFileStreamReader::Read(net::IOBuffer* buffer, | |
31 int buffer_length, | |
32 const net::CompletionCallback& callback) { | |
33 // Return as much as available in the internal buffer. It may be less than | |
34 // |buffer_length|, what is valid. | |
35 const int bytes_read = | |
36 CopyFromBuffer(make_scoped_refptr(buffer), buffer_length); | |
37 if (bytes_read) | |
38 return bytes_read; | |
39 | |
40 // Nothing copied, so contents have to be preloaded. | |
41 Preload(base::Bind(&BufferingFileStreamReader::OnPreloadCompleted, | |
42 weak_ptr_factory_.GetWeakPtr(), | |
43 make_scoped_refptr(buffer), | |
44 buffer_length, | |
45 callback)); | |
46 | |
47 return net::ERR_IO_PENDING; | |
48 } | |
49 | |
50 int64 BufferingFileStreamReader::GetLength( | |
51 const net::Int64CompletionCallback& callback) { | |
52 return file_stream_reader_->GetLength(callback); | |
53 } | |
54 | |
55 int BufferingFileStreamReader::CopyFromBuffer( | |
56 scoped_refptr<net::IOBuffer> buffer, | |
57 int buffer_length) { | |
58 const int read_bytes = std::min(buffer_length, buffered_bytes_); | |
59 | |
60 memcpy(buffer->data(), | |
61 preloading_buffer_->data() + preloading_buffer_offset_, | |
62 read_bytes); | |
63 preloading_buffer_offset_ += read_bytes; | |
64 buffered_bytes_ -= read_bytes; | |
65 | |
66 return read_bytes; | |
67 } | |
68 | |
69 void BufferingFileStreamReader::Preload( | |
70 const net::CompletionCallback& callback) { | |
71 // TODO(mtomasz): Dynamically calculate the chunk size. Start from a small | |
72 // one, then increase for consecutive requests. That would improve performance | |
73 // when reading just small chunks, instead of the entire file. | |
74 const int preload_bytes = buffer_size_; | |
75 | |
76 const int result = | |
77 file_stream_reader_->Read(preloading_buffer_, preload_bytes, callback); | |
78 | |
79 if (result != net::ERR_IO_PENDING) { | |
80 base::MessageLoopProxy::current()->PostTask(FROM_HERE, | |
81 base::Bind(callback, result)); | |
82 } | |
83 } | |
84 | |
85 void BufferingFileStreamReader::OnPreloadCompleted( | |
86 scoped_refptr<net::IOBuffer> buffer, | |
87 int buffer_length, | |
88 const net::CompletionCallback& callback, | |
89 int result) { | |
90 if (result < 0) { | |
91 callback.Run(result); | |
92 return; | |
93 } | |
94 | |
95 preloading_buffer_offset_ = 0; | |
96 buffered_bytes_ = result; | |
97 | |
98 const int copy_result = CopyFromBuffer(buffer, buffer_length); | |
99 base::MessageLoopProxy::current()->PostTask( | |
100 FROM_HERE, base::Bind(callback, copy_result)); | |
hashimoto
2014/06/05 10:07:10
No need to post task here as OnPreloadCompleted()
mtomasz
2014/06/06 01:31:03
Done.
| |
101 } | |
102 | |
103 } // namespace file_system_provider | |
104 } // namespace chromeos | |
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