net/spdy/hpack_encoding_context.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 NET_SPDY_HPACK_ENCODING_CONTEXT_H_
   6 #define NET_SPDY_HPACK_ENCODING_CONTEXT_H_
   7
   8 #include <cstddef>
   9 #include <deque>
  10 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/macros.h"
  14 #include "base/strings/string_piece.h"
  15 #include "net/base/net_export.h"
  16 #include "net/spdy/hpack_header_table.h"
  17
  18 // All section references below are to
  19 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-04
  20 // .
  21
  22 namespace net {
  23
  24 // An encoding context is simply a header table and its associated
  25 // reference set and a static table.
  26 class NET_EXPORT_PRIVATE HpackEncodingContext {
  27  public:
  28   // The constant returned by GetTouchesAt() if the indexed entry
  29   // hasn't been touched (which is distinct from having a touch count
  30   // of 0).
  31   //
  32   // TODO(akalin): The distinction between untouched and having a
  33   // touch count of 0 is confusing. Think of a better way to represent
  34   // this state.
  35   static const uint32 kUntouched;
  36
  37   HpackEncodingContext();
  38
  39   ~HpackEncodingContext();
  40
  41   uint32 GetEntryCount() const;
  42
  43   // For all accessor below, index must be < GetEntryCount().
  44
  45   // The StringPieces returned by Get{Name,Value}At() live as long as
  46   // the next call to SetMaxSize() or the Process*() functions.
  47
  48   base::StringPiece GetNameAt(uint32 index) const;
  49
  50   base::StringPiece GetValueAt(uint32 index) const;
  51
  52   bool IsReferencedAt(uint32 index) const;
  53
  54   uint32 GetTouchCountAt(uint32 index) const;
  55
  56   void SetReferencedAt(uint32 index, bool referenced);
  57
  58   // Adds the given number of touches to the entry at the given
  59   // index. It is guaranteed that GetTouchCountAt(index) will not
  60   // equal kUntouched after this function is called (even if
  61   // touch_count == 0).
  62   void AddTouchesAt(uint32 index, uint32 touch_count);
  63
  64   // Sets the touch count of the entry at the given index to
  65   // kUntouched.
  66   void ClearTouchesAt(uint32 index);
  67
  68   // Sets the maximum size of the encoding text, evicting entries if
  69   // necessary.
  70   void SetMaxSize(uint32 max_size);
  71
  72   // The Process*() functions below return true on success and false
  73   // if an error was encountered.
  74
  75   // Tries to update the encoding context given an indexed header
  76   // opcode for the given index as described in 3.2.1. new_index is
  77   // filled in with the index of a mutable entry, or -1 if one was not
  78   // able to be created. removed_referenced_indices is filled in with
  79   // the indices of all entries removed from the reference set.
  80   bool ProcessIndexedHeader(uint32 index,
  81                             int32* new_index,
  82                             std::vector<uint32>* removed_referenced_indices);
  83
  84   // Tries to update the encoding context given a literal header with
  85   // incremental indexing opcode for the given name and value as
  86   // described in 3.2.1. index is filled in with the index of the new
  87   // entry if the header was successfully indexed, or -1 if
  88   // not. removed_referenced_indices is filled in with the indices of
  89   // all entries removed from the reference set.
  90   bool ProcessLiteralHeaderWithIncrementalIndexing(
  91       base::StringPiece name,
  92       base::StringPiece value,
  93       int32* index,
  94       std::vector<uint32>* removed_referenced_indices);
  95
  96  private:
  97   HpackHeaderTable header_table_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(HpackEncodingContext);
 100 };
 101
 102 }  // namespace net
 103
 104 #endif  // NET_SPDY_HPACK_ENCODING_CONTEXT_H_