net/websockets/websocket_deflate_predictor.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 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
  12 namespace net {
  13
  14 struct WebSocketFrame;
  15
  16 // WebSocketDeflatePredictor is an interface class used for judging whether
  17 // a WebSocketDeflateStream should compress a message or not.
  18 class 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_