| // 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_HEADER_TABLE_H_ |
| #define NET_SPDY_HPACK_HEADER_TABLE_H_ |
| |
| #include <cstddef> |
| #include <deque> |
| #include <set> |
| |
| #include "base/basictypes.h" |
| #include "base/macros.h" |
| #include "net/base/net_export.h" |
| #include "net/spdy/hpack_entry.h" |
| |
| // All section references below are to |
| // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-07 |
| |
| namespace net { |
| |
| namespace test { |
| class HpackHeaderTablePeer; |
| } // namespace test |
| |
| // A data structure for both the header table (described in 3.1.2) and |
| // the reference set (3.1.3). |
| class NET_EXPORT_PRIVATE HpackHeaderTable { |
| public: |
| friend class test::HpackHeaderTablePeer; |
| |
| // HpackHeaderTable takes advantage of the deque property that references |
| // remain valid, so long as insertions & deletions are at the head & tail. |
| // If this changes (eg we start to drop entries from the middle of the table), |
| // this needs to be a std::list, in which case |index_| can be trivially |
| // extended to map to list iterators. |
| typedef std::deque<HpackEntry> EntryTable; |
| |
| // Implements a total ordering of HpackEntry on name(), value(), then index |
| // ascending. Note that index may change over the lifetime of an HpackEntry, |
| // but the relative index order of two entries will not. This comparator is |
| // composed with the 'lookup' HpackEntry constructor to allow for efficient |
| // lower-bounding of matching entries. |
| struct NET_EXPORT_PRIVATE EntryComparator { |
| explicit EntryComparator(HpackHeaderTable* table) : table_(table) {} |
| |
| bool operator() (const HpackEntry* lhs, const HpackEntry* rhs) const; |
| |
| private: |
| HpackHeaderTable* table_; |
| }; |
| typedef std::set<HpackEntry*, EntryComparator> OrderedEntrySet; |
| |
| HpackHeaderTable(); |
| |
| ~HpackHeaderTable(); |
| |
| // Last-aknowledged value of SETTINGS_HEADER_TABLE_SIZE. |
| size_t settings_size_bound() { return settings_size_bound_; } |
| |
| // Current and maximum estimated byte size of the table, as described in |
| // 3.3.1. 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_; } |
| |
| const OrderedEntrySet& reference_set() { |
| return reference_set_; |
| } |
| |
| // Returns the entry matching the index, or NULL. |
| HpackEntry* GetByIndex(size_t index); |
| |
| // Returns the lowest-value entry having |name|, or NULL. |
| HpackEntry* GetByName(base::StringPiece name); |
| |
| // Returns the lowest-index matching entry, or NULL. |
| HpackEntry* GetByNameAndValue(base::StringPiece name, |
| base::StringPiece 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 3.3.2. |
| 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 3.3.3. No eviction |
| // actually occurs. The set is returned via range [begin_out, end_out). |
| void EvictionSet(base::StringPiece name, base::StringPiece 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. |
| HpackEntry* TryAddEntry(base::StringPiece name, base::StringPiece value); |
| |
| // Toggles the presence of a dynamic entry in the reference set. Returns |
| // true if the entry was added, or false if removed. It is an error to |
| // Toggle(entry) if |entry->state()| != 0. |
| bool Toggle(HpackEntry* entry); |
| |
| // Removes all entries from the reference set. Sets the state of each removed |
| // entry to zero. |
| void ClearReferenceSet(); |
| |
| void DebugLogTableState() const; |
| |
| private: |
| // Returns number of evictions required to enter |name| & |value|. |
| size_t EvictionCountForEntry(base::StringPiece name, |
| base::StringPiece 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); |
| |
| EntryTable dynamic_entries_; |
| EntryTable static_entries_; |
| |
| // Full table index, over |dynamic_entries_| and |static_entries_|. |
| OrderedEntrySet index_; |
| // The reference set is strictly a subset of |dynamic_entries_|. |
| OrderedEntrySet reference_set_; |
| |
| // 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_header_table_size_| |
| 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_; |
| |
| DISALLOW_COPY_AND_ASSIGN(HpackHeaderTable); |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_SPDY_HPACK_HEADER_TABLE_H_ |