blob: 44024b679e3a757dd56a8b7dc081d8b6a97b1bdd [file] [log] [blame]
// Copyright (c) 2018 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.
#include <memory>
#include "quic/platform/api/quic_export.h"
#include "quic/platform/api/quic_flag_utils.h"
#include "quic/platform/api/quic_flags.h"
#include "quic/platform/api/quic_logging.h"
#include "common/quiche_linked_hash_map.h"
namespace quic {
// A LRU cache that maps from type Key to Value* in QUIC.
// This cache CANNOT be shared by multiple threads (even with locks) because
// Value* returned by Lookup() can be invalid if the entry is evicted by other
// threads.
template <class K, class V, class Hash = std::hash<K>,
class Eq = std::equal_to<K>>
class QUIC_NO_EXPORT QuicLRUCache {
using HashMapType =
typename quiche::QuicheLinkedHashMap<K, std::unique_ptr<V>, Hash, Eq>;
// The iterator, if valid, points to std::pair<K, std::unique_ptr<V>>.
using iterator = typename HashMapType::iterator;
using const_iterator = typename HashMapType::const_iterator;
using reverse_iterator = typename HashMapType::reverse_iterator;
using const_reverse_iterator = typename HashMapType::const_reverse_iterator;
explicit QuicLRUCache(size_t capacity) : capacity_(capacity) {}
QuicLRUCache(const QuicLRUCache&) = delete;
QuicLRUCache& operator=(const QuicLRUCache&) = delete;
iterator begin() { return cache_.begin(); }
const_iterator begin() const { return cache_.begin(); }
iterator end() { return cache_.end(); }
const_iterator end() const { return cache_.end(); }
reverse_iterator rbegin() { return cache_.rbegin(); }
const_reverse_iterator rbegin() const { return cache_.rbegin(); }
reverse_iterator rend() { return cache_.rend(); }
const_reverse_iterator rend() const { return cache_.rend(); }
// Inserts one unit of |key|, |value| pair to the cache. Cache takes ownership
// of inserted |value|.
void Insert(const K& key, std::unique_ptr<V> value) {
auto it = cache_.find(key);
if (it != cache_.end()) {
cache_.emplace(key, std::move(value));
if (cache_.size() > capacity_) {
QUICHE_DCHECK_LE(cache_.size(), capacity_);
iterator Lookup(const K& key) {
auto iter = cache_.find(key);
if (iter == cache_.end()) {
return iter;
std::unique_ptr<V> value = std::move(iter->second);
auto result = cache_.emplace(key, std::move(value));
return result.first;
iterator Erase(iterator iter) { return cache_.erase(iter); }
// Removes all entries from the cache.
void Clear() { cache_.clear(); }
// Returns maximum size of the cache.
size_t MaxSize() const { return capacity_; }
// Returns current size of the cache.
size_t Size() const { return cache_.size(); }
quiche::QuicheLinkedHashMap<K, std::unique_ptr<V>, Hash, Eq> cache_;
const size_t capacity_;
} // namespace quic