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 NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PREDICTOR_H_
6#define NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PREDICTOR_H_
7
8#include "base/basictypes.h"
9#include "base/memory/scoped_vector.h"
10#include "net/base/net_export.h"
11
12namespace net {
13
14struct WebSocketFrame;
15
16// WebSocketDeflatePredictor is an interface class used for judging whether
17// a WebSocketDeflateStream should compress a message or not.
18class NET_EXPORT_PRIVATE WebSocketDeflatePredictor {
19 public:
20  enum Result {
21    // Deflate and send the message.
22    DEFLATE,
23    // Do not deflate and send the original message.
24    DO_NOT_DEFLATE,
25    // Try compressing the message and send the smaller one of the original
26    // and the compressed message.
27    // Returning this result implies that the deflater is running on
28    // DoNotTakeOverContext mode and the entire message is visible.
29    TRY_DEFLATE,
30  };
31
32  virtual ~WebSocketDeflatePredictor() {}
33
34  // Predicts and returns whether the deflater should deflate the message
35  // which begins with |frames[frame_index]| or not.
36  // |frames[(frame_index + 1):]| consists of future frames if any.
37  // |frames[frame_index]| must be the first frame of a data message,
38  // but future frames may contain control message frames.
39  // |frames[frame_index]| cannot be recorded yet and all preceding
40  // data frames have to be already recorded when this method is called.
41  virtual Result Predict(const ScopedVector<WebSocketFrame>& frames,
42                         size_t frame_index) = 0;
43
44  // Records frame data for future prediction.
45  // Only data frames should be recorded. Do not pass control frames' data.
46  // All input data frames for the stream must be recorded in order.
47  virtual void RecordInputDataFrame(const WebSocketFrame* frame) = 0;
48
49  // Records frame data for future prediction.
50  // Only data frames should be recorded. Do not pass control frames' data.
51  // All data frames written by the stream must be recorded in order
52  // regardless of whether they are compressed or not.
53  virtual void RecordWrittenDataFrame(const WebSocketFrame* frame) = 0;
54};
55
56}  // namespace net
57
58#endif  // NET_WEBSOCKETS_WEBSOCKET_DEFLATE_PREDICTOR_H_
59