| // 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 <memory> |
| #include <vector> |
| |
| #include "absl/container/flat_hash_map.h" |
| #include "absl/strings/string_view.h" |
| #include "quiche/common/platform/api/quiche_export.h" |
| #include "quiche/common/quiche_circular_deque.h" |
| #include "quiche/spdy/core/hpack/hpack_entry.h" |
| |
| // All section references below are to http://tools.ietf.org/html/rfc7541. |
| |
| namespace spdy { |
| |
| namespace test { |
| class HpackHeaderTablePeer; |
| } // namespace test |
| |
| // Return value of GetByName() and GetByNameAndValue() if matching entry is not |
| // found. This value is never used in HPACK for indexing entries, see |
| // https://httpwg.org/specs/rfc7541.html#index.address.space. |
| inline constexpr size_t kHpackEntryNotFound = 0; |
| |
| // A data structure for the static table (2.3.1) and the dynamic table (2.3.2). |
| class QUICHE_EXPORT HpackHeaderTable { |
| public: |
| friend class test::HpackHeaderTablePeer; |
| |
| // Use a lightweight, memory efficient container for the static table, which |
| // is initialized once and never changed after. |
| using StaticEntryTable = std::vector<HpackEntry>; |
| |
| // HpackHeaderTable takes advantage of the deque property that references |
| // remain valid, so long as insertions & deletions are at the head & tail. |
| using DynamicEntryTable = |
| quiche::QuicheCircularDeque<std::unique_ptr<HpackEntry>>; |
| |
| using NameValueToEntryMap = absl::flat_hash_map<HpackLookupEntry, size_t>; |
| using NameToEntryMap = absl::flat_hash_map<absl::string_view, size_t>; |
| |
| 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_; } |
| |
| // The HPACK indexing scheme used by GetByName() and GetByNameAndValue() is |
| // defined at https://httpwg.org/specs/rfc7541.html#index.address.space. |
| |
| // Returns the index of the lowest-index entry matching |name|, |
| // or kHpackEntryNotFound if no matching entry is found. |
| size_t GetByName(absl::string_view name); |
| |
| // Returns the index of the lowest-index entry matching |name| and |value|, |
| // or kHpackEntryNotFound if no matching entry is found. |
| size_t GetByNameAndValue(absl::string_view name, absl::string_view value); |
| |
| // 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(absl::string_view name, absl::string_view value, |
| DynamicEntryTable::iterator* begin_out, |
| DynamicEntryTable::iterator* end_out); |
| |
| // Adds an entry for the representation, evicting entries as needed. |name| |
| // and |value| must not point to an entry in |dynamic_entries_| which is about |
| // to be evicted, but they may point to an entry which is not. |
| // 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(absl::string_view name, |
| absl::string_view value); |
| |
| private: |
| // Returns number of evictions required to enter |name| & |value|. |
| size_t EvictionCountForEntry(absl::string_view name, |
| absl::string_view 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. |
| |
| // Stores HpackEntries. |
| const StaticEntryTable& static_entries_; |
| DynamicEntryTable dynamic_entries_; |
| |
| // Tracks the index of the unique HpackEntry for a given header name and |
| // value. Keys consist of string_views that point to strings stored in |
| // |static_entries_|. |
| const NameValueToEntryMap& static_index_; |
| |
| // Tracks the index of the first static entry for each name in the static |
| // table. Each key is a string_view that points to a name string stored in |
| // |static_entries_|. |
| const NameToEntryMap& static_name_index_; |
| |
| // Tracks the index of the most recently inserted HpackEntry for a given |
| // header name and value. Keys consist of string_views that point to strings |
| // stored in |dynamic_entries_|. |
| NameValueToEntryMap dynamic_index_; |
| |
| // Tracks the index of the most recently inserted HpackEntry for a given |
| // header name. Each key is a string_view that points to a name string stored |
| // in |dynamic_entries_|. |
| 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 dynamic table insertions so far |
| // (including entries that have been evicted). |
| size_t dynamic_table_insertions_; |
| }; |
| |
| } // namespace spdy |
| |
| #endif // QUICHE_SPDY_CORE_HPACK_HPACK_HEADER_TABLE_H_ |