| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkLRUCache_DEFINED |
| #define SkLRUCache_DEFINED |
| |
| #include "include/private/SkChecksum.h" |
| #include "include/private/SkTHash.h" |
| #include "src/core/SkTInternalLList.h" |
| |
| /** |
| * A generic LRU cache. |
| */ |
| template <typename K, typename V, typename HashK = SkGoodHash> |
| class SkLRUCache : public SkNoncopyable { |
| private: |
| struct Entry { |
| Entry(const K& key, V&& value) |
| : fKey(key) |
| , fValue(std::move(value)) {} |
| |
| K fKey; |
| V fValue; |
| |
| SK_DECLARE_INTERNAL_LLIST_INTERFACE(Entry); |
| }; |
| |
| public: |
| explicit SkLRUCache(int maxCount) |
| : fMaxCount(maxCount) {} |
| |
| ~SkLRUCache() { |
| Entry* node = fLRU.head(); |
| while (node) { |
| fLRU.remove(node); |
| delete node; |
| node = fLRU.head(); |
| } |
| } |
| |
| V* find(const K& key) { |
| Entry** value = fMap.find(key); |
| if (!value) { |
| return nullptr; |
| } |
| Entry* entry = *value; |
| if (entry != fLRU.head()) { |
| fLRU.remove(entry); |
| fLRU.addToHead(entry); |
| } // else it's already at head position, don't need to do anything |
| return &entry->fValue; |
| } |
| |
| V* insert(const K& key, V value) { |
| Entry* entry = new Entry(key, std::move(value)); |
| fMap.set(entry); |
| fLRU.addToHead(entry); |
| while (fMap.count() > fMaxCount) { |
| this->remove(fLRU.tail()->fKey); |
| } |
| return &entry->fValue; |
| } |
| |
| int count() { |
| return fMap.count(); |
| } |
| |
| template <typename Fn> // f(K*, V*) |
| void foreach(Fn&& fn) { |
| typename SkTInternalLList<Entry>::Iter iter; |
| for (Entry* e = iter.init(fLRU, SkTInternalLList<Entry>::Iter::kHead_IterStart); e; |
| e = iter.next()) { |
| fn(&e->fKey, &e->fValue); |
| } |
| } |
| |
| void reset() { |
| fMap.reset(); |
| for (Entry* e = fLRU.head(); e; e = fLRU.head()) { |
| fLRU.remove(e); |
| delete e; |
| } |
| } |
| |
| private: |
| struct Traits { |
| static const K& GetKey(Entry* e) { |
| return e->fKey; |
| } |
| |
| static uint32_t Hash(const K& k) { |
| return HashK()(k); |
| } |
| }; |
| |
| void remove(const K& key) { |
| Entry** value = fMap.find(key); |
| SkASSERT(value); |
| Entry* entry = *value; |
| SkASSERT(key == entry->fKey); |
| fMap.remove(key); |
| fLRU.remove(entry); |
| delete entry; |
| } |
| |
| int fMaxCount; |
| SkTHashTable<Entry*, K, Traits> fMap; |
| SkTInternalLList<Entry> fLRU; |
| }; |
| |
| #endif |