HPACK: Refactor and expand HpackHeaderTable indexing.

net/spdy/hpack_encoding_context.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef NET_SPDY_HPACK_ENCODING_CONTEXT_H_
-#define NET_SPDY_HPACK_ENCODING_CONTEXT_H_
-
-#include <cstddef>
-#include <deque>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/macros.h"
-#include "base/strings/string_piece.h"
-#include "net/base/net_export.h"
-#include "net/spdy/hpack_header_table.h"
-
-// All section references below are to
-// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-06
-
-namespace net {
-
-namespace test {
-class HpackEncodingContextPeer;
-}  // namespace test
-
-// An encoding context is simply a header table and its associated
-// reference set and a static table.
-class NET_EXPORT_PRIVATE HpackEncodingContext {
- public:
-  friend class test::HpackEncodingContextPeer;
-
-  // The constant returned by GetTouchesAt() if the indexed entry
-  // hasn't been touched (which is distinct from having a touch count
-  // of 0).
-  //
-  // TODO(akalin): The distinction between untouched and having a
-  // touch count of 0 is confusing. Think of a better way to represent
-  // this state.
-  static const uint32 kUntouched;
-
-  HpackEncodingContext();
-
-  ~HpackEncodingContext();
-
-  uint32 GetMutableEntryCount() const;
-
-  uint32 GetEntryCount() const;
-
-  // For all read accessors below, index must be >= 1 and <=
-  // GetEntryCount().  For all mutating accessors below, index must be
-  // >= 1 and <= GetMutableEntryCount().
-
-  // The StringPieces returned by Get{Name,Value}At() live as long as
-  // the next call to SetMaxSize() or the Process*() functions.
-
-  base::StringPiece GetNameAt(uint32 index) const;
-
-  base::StringPiece GetValueAt(uint32 index) const;
-
-  bool IsReferencedAt(uint32 index) const;
-
-  uint32 GetTouchCountAt(uint32 index) const;
-
-  void SetReferencedAt(uint32 index, bool referenced);
-
-  // Adds the given number of touches to the entry at the given
-  // index. It is guaranteed that GetTouchCountAt(index) will not
-  // equal kUntouched after this function is called (even if
-  // touch_count == 0).
-  void AddTouchesAt(uint32 index, uint32 touch_count);
-
-  // Sets the touch count of the entry at the given index to
-  // kUntouched.
-  void ClearTouchesAt(uint32 index);
-
-  // Called upon acknowledgement of SETTINGS_HEADER_TABLE_SIZE.
-  // If |max_size| is smaller than the current header table size, the change
-  // is treated as an implicit maximum-size context update.
-  void ApplyHeaderTableSizeSetting(uint32 max_size);
-
-  // The Process*() functions below return true on success and false
-  // if an error was encountered.
-
-  // Section 4.4. Sets the maximum size of the header table, evicting entries
-  // as needed. Fails if |max_size| is larger than SETTINGS_HEADER_TABLE_SIZE.
-  bool ProcessContextUpdateNewMaximumSize(uint32 max_size);
-
-  // Section 4.4. Drops all headers from the reference set.
-  bool ProcessContextUpdateEmptyReferenceSet();
-
-  // Tries to update the encoding context given an indexed header
-  // opcode for the given index as described in section 3.2.1.
-  // new_index is filled in with the index of a mutable entry,
-  // or 0 if one was not created. removed_referenced_indices is filled
-  // in with the indices of all entries removed from the reference set.
-  bool ProcessIndexedHeader(uint32 nonzero_index,
-                            uint32* new_index,
-                            std::vector<uint32>* removed_referenced_indices);
-
-  // Tries to update the encoding context given a literal header with
-  // incremental indexing opcode for the given name and value as
-  // described in 3.2.1. index is filled in with the index of the new
-  // entry if the header was successfully indexed, or 0 if
-  // not. removed_referenced_indices is filled in with the indices of
-  // all entries removed from the reference set.
-  bool ProcessLiteralHeaderWithIncrementalIndexing(
-      base::StringPiece name,
-      base::StringPiece value,
-      uint32* index,
-      std::vector<uint32>* removed_referenced_indices);
-
- private:
-  // Last acknowledged value for SETTINGS_HEADER_TABLE_SIZE.
-  uint32 settings_header_table_size_;
-
-  HpackHeaderTable header_table_;
-
-  DISALLOW_COPY_AND_ASSIGN(HpackEncodingContext);
-};
-
-}  // namespace net
-
-#endif  // NET_SPDY_HPACK_ENCODING_CONTEXT_H_