| // 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 QUICHE_SPDY_CORE_HPACK_HPACK_HEADER_TABLE_H_ |
| #define QUICHE_SPDY_CORE_HPACK_HPACK_HEADER_TABLE_H_ |
| |
| #include <cstddef> |
| #include <cstdint> |
| #include <deque> |
| #include <memory> |
| |
| #include "net/third_party/quiche/src/spdy/core/hpack/hpack_entry.h" |
| #include "net/third_party/quiche/src/spdy/platform/api/spdy_containers.h" |
| #include "net/third_party/quiche/src/spdy/platform/api/spdy_export.h" |
| #include "net/third_party/quiche/src/spdy/platform/api/spdy_macros.h" |
| #include "net/third_party/quiche/src/spdy/platform/api/spdy_string_piece.h" |
| |
| // All section references below are to http://tools.ietf.org/html/rfc7541. |
| |
| namespace spdy { |
| |
| namespace test { |
| class HpackHeaderTablePeer; |
| } // namespace test |
| |
| // A data structure for the static table (2.3.1) and the dynamic table (2.3.2). |
| class SPDY_EXPORT_PRIVATE HpackHeaderTable { |
| public: |
| friend class test::HpackHeaderTablePeer; |
| |
| // Debug visitor my be used to extract debug/internal information |
| // about the HpackHeaderTable as it operates. |
| // |
| // Most HpackHeaderTable implementations do not need to bother with |
| // this interface at all. |
| class DebugVisitorInterface { |
| public: |
| virtual ~DebugVisitorInterface() {} |
| |
| // |OnNewEntry()| and |OnUseEntry()| can be used together to |
| // gather data about the distribution of time intervals between |
| // creation and reference of entries in the dynamic table. The |
| // data is desired to sanity check a proposed extension to HPACK |
| // for QUIC that would eliminate inter-stream head of line |
| // blocking (due to standard HPACK). The visitor should return |
| // the current time from |OnNewEntry()|, which will be passed |
| // to |OnUseEntry()| each time that particular entry is used to |
| // emit an indexed representation. |
| virtual int64_t OnNewEntry(const HpackEntry& entry) = 0; |
| virtual void OnUseEntry(const HpackEntry& entry) = 0; |
| }; |
| |
| // HpackHeaderTable takes advantage of the deque property that references |
| // remain valid, so long as insertions & deletions are at the head & tail. |
| // This precludes the use of base::circular_deque. |
| // |
| // If this changes (we want to change to circular_deque or we start to drop |
| // entries from the middle of the table), this should to be a std::list, in |
| // which case |*_index_| can be trivially extended to map to list iterators. |
| using EntryTable = std::deque<HpackEntry>; |
| |
| struct SPDY_EXPORT_PRIVATE EntryHasher { |
| size_t operator()(const HpackEntry* entry) const; |
| }; |
| struct SPDY_EXPORT_PRIVATE EntriesEq { |
| bool operator()(const HpackEntry* lhs, const HpackEntry* rhs) const; |
| }; |
| using UnorderedEntrySet = SpdyHashSet<HpackEntry*, EntryHasher, EntriesEq>; |
| using NameToEntryMap = |
| SpdyHashMap<SpdyStringPiece, const HpackEntry*, SpdyStringPieceHash>; |
| |
| HpackHeaderTable(); |
| HpackHeaderTable(const HpackHeaderTable&) = delete; |
| HpackHeaderTable& operator=(const HpackHeaderTable&) = delete; |
| |
| ~HpackHeaderTable(); |
| |
| // Last-acknowledged value of SETTINGS_HEADER_TABLE_SIZE. |
| size_t settings_size_bound() const { return settings_size_bound_; } |
| |
| // Current and maximum estimated byte size of the table, as described in |
| // 4.1. Notably, this is /not/ the number of entries in the table. |
| size_t size() const { return size_; } |
| size_t max_size() const { return max_size_; } |
| |
| // Returns the entry matching the index, or NULL. |
| const HpackEntry* GetByIndex(size_t index); |
| |
| // Returns the lowest-value entry having |name|, or NULL. |
| const HpackEntry* GetByName(SpdyStringPiece name); |
| |
| // Returns the lowest-index matching entry, or NULL. |
| const HpackEntry* GetByNameAndValue(SpdyStringPiece name, |
| SpdyStringPiece value); |
| |
| // Returns the index of an entry within this header table. |
| size_t IndexOf(const HpackEntry* entry) const; |
| |
| // Sets the maximum size of the header table, evicting entries if |
| // necessary as described in 5.2. |
| void SetMaxSize(size_t max_size); |
| |
| // Sets the SETTINGS_HEADER_TABLE_SIZE bound of the table. Will call |
| // SetMaxSize() as needed to preserve max_size() <= settings_size_bound(). |
| void SetSettingsHeaderTableSize(size_t settings_size); |
| |
| // Determine the set of entries which would be evicted by the insertion |
| // of |name| & |value| into the table, as per section 4.4. No eviction |
| // actually occurs. The set is returned via range [begin_out, end_out). |
| void EvictionSet(SpdyStringPiece name, |
| SpdyStringPiece value, |
| EntryTable::iterator* begin_out, |
| EntryTable::iterator* end_out); |
| |
| // Adds an entry for the representation, evicting entries as needed. |name| |
| // and |value| must not be owned by an entry which could be evicted. The |
| // added HpackEntry is returned, or NULL is returned if all entries were |
| // evicted and the empty table is of insufficent size for the representation. |
| const HpackEntry* TryAddEntry(SpdyStringPiece name, SpdyStringPiece value); |
| |
| void DebugLogTableState() const SPDY_UNUSED; |
| |
| void set_debug_visitor(std::unique_ptr<DebugVisitorInterface> visitor) { |
| debug_visitor_ = std::move(visitor); |
| } |
| |
| // Returns the estimate of dynamically allocated memory in bytes. |
| size_t EstimateMemoryUsage() const; |
| |
| private: |
| // Returns number of evictions required to enter |name| & |value|. |
| size_t EvictionCountForEntry(SpdyStringPiece name, |
| SpdyStringPiece value) const; |
| |
| // Returns number of evictions required to reclaim |reclaim_size| table size. |
| size_t EvictionCountToReclaim(size_t reclaim_size) const; |
| |
| // Evicts |count| oldest entries from the table. |
| void Evict(size_t count); |
| |
| // |static_entries_|, |static_index_|, and |static_name_index_| are owned by |
| // HpackStaticTable singleton. |
| |
| // Tracks HpackEntries by index. |
| const EntryTable& static_entries_; |
| EntryTable dynamic_entries_; |
| |
| // Tracks the unique HpackEntry for a given header name and value. |
| const UnorderedEntrySet& static_index_; |
| |
| // Tracks the first static entry for each name in the static table. |
| const NameToEntryMap& static_name_index_; |
| |
| // Tracks the most recently inserted HpackEntry for a given header name and |
| // value. |
| UnorderedEntrySet dynamic_index_; |
| |
| // Tracks the most recently inserted HpackEntry for a given header name. |
| NameToEntryMap dynamic_name_index_; |
| |
| // Last acknowledged value for SETTINGS_HEADER_TABLE_SIZE. |
| size_t settings_size_bound_; |
| |
| // Estimated current and maximum byte size of the table. |
| // |max_size_| <= |settings_size_bound_| |
| size_t size_; |
| size_t max_size_; |
| |
| // Total number of table insertions which have occurred. Referenced by |
| // IndexOf() for determination of an HpackEntry's table index. |
| size_t total_insertions_; |
| |
| std::unique_ptr<DebugVisitorInterface> debug_visitor_; |
| }; |
| |
| } // namespace spdy |
| |
| #endif // QUICHE_SPDY_CORE_HPACK_HPACK_HEADER_TABLE_H_ |