LRU map (cache) implementation to o3tl + tests
Change-Id: I6b1a39918e6c8c67712be2c8e9907266dcfefedb
This commit is contained in:
Tomaž Vajngerl
parent
450727fdff
commit
80a9213480
3 changed files with 381 additions and 0 deletions
141
include/o3tl/lru_map.hxx
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141
include/o3tl/lru_map.hxx
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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*/
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#ifndef INCLUDED_O3TL_LRU_MAP_HXX
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#define INCLUDED_O3TL_LRU_MAP_HXX
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#include <list>
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#include <unordered_map>
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namespace o3tl
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{
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/** LRU map
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*
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* Similar to unordered_map (it actually uses it) with additionaly functionality
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* which removes the entries that have been "least recently used" when the size
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* hits the specified capacity.
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*
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* It only implements the minimal methods needed and the implementation is NOT
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* thread safe.
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*
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* The implementation is as simple as possible but it still uses O(1) complexity
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* for most of the operations with a combination unordered map and linked list.
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*
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**/
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template<typename Key, typename Value, class KeyHash = std::hash<Key>>
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class lru_map SAL_FINAL
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{
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private:
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typedef typename std::pair<Key, Value> key_value_pair_t;
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typedef std::list<key_value_pair_t> list_t;
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typedef typename list_t::iterator list_iterator_t;
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typedef typename list_t::const_iterator list_const_iterator_t;
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typedef std::unordered_map<Key, list_iterator_t, KeyHash> map_t;
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typedef typename map_t::iterator map_iterator_t;
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typedef typename map_t::const_iterator map_const_iterator_t;
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list_t mLruList;
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map_t mLruMap;
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const size_t mMaxSize;
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inline void checkLRU()
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{
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if (mLruMap.size() > mMaxSize)
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{
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// remove from map
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mLruMap.erase(mLruList.back().first);
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// remove from list
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mLruList.pop_back();
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}
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}
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public:
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typedef list_iterator_t iterator;
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typedef list_const_iterator_t const_iterator;
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lru_map(size_t nMaxSize)
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: mMaxSize(nMaxSize)
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{}
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void insert(key_value_pair_t& rPair)
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{
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map_iterator_t iterator = mLruMap.find(rPair.first);
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if (iterator == mLruMap.end()) // doesn't exist -> add to queue and map
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{
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// add to front of the list
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mLruList.push_front(rPair);
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// add the list position (iterator) to the map
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mLruMap[rPair.first] = mLruList.begin();
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checkLRU();
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}
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else // already exists -> replace value
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{
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// replace value
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iterator->second->second = rPair.second;
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// bring to front of the lru list
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mLruList.splice(mLruList.begin(), mLruList, iterator->second);
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}
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}
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void insert(key_value_pair_t&& rPair)
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{
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map_iterator_t iterator = mLruMap.find(rPair.first);
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if (iterator == mLruMap.end()) // doesn't exist -> add to list and map
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{
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// add to front of the list
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mLruList.push_front(std::move(rPair));
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// add the list position (iterator) to the map
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mLruMap[rPair.first] = mLruList.begin();
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checkLRU();
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}
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else // already exists -> replace value
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{
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// replace value
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iterator->second->second = std::move(rPair.second);
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// push to back of the lru list
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mLruList.splice(mLruList.begin(), mLruList, iterator->second);
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}
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}
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const list_const_iterator_t find(const Key& key)
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{
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const map_iterator_t iterator = mLruMap.find(key);
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if (iterator == mLruMap.cend()) // can't find entry for the key
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{
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// return empty iterator
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return mLruList.cend();
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}
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else
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{
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// push to back of the lru list
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mLruList.splice(mLruList.begin(), mLruList, iterator->second);
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return iterator->second;
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}
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}
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const list_const_iterator_t end() const
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{
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return mLruList.end();
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}
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size_t size() const
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{
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return mLruList.size();
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}
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};
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}
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#endif /* INCLUDED_O3TL_LRU_MAP_HXX */
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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@ -33,6 +33,7 @@ $(eval $(call gb_CppunitTest_add_exception_objects,o3tl_tests,\
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o3tl/qa/test-vector_pool \
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o3tl/qa/test-sorted_vector \
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o3tl/qa/test-typed_flags \
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o3tl/qa/test-lru_map \
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))
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# vim: set noet sw=4:
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239
o3tl/qa/test-lru_map.cxx
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o3tl/qa/test-lru_map.cxx
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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*/
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#include <sal/types.h>
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#include "cppunit/TestAssert.h"
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#include "cppunit/TestFixture.h"
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#include "cppunit/extensions/HelperMacros.h"
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#include <o3tl/lru_map.hxx>
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#include <boost/functional/hash.hpp>
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using namespace ::o3tl;
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class lru_map_test : public CppUnit::TestFixture
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{
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public:
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void testBaseUsage();
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void testReplaceKey();
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void testReplaceValue();
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void testLruRemoval();
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void testCustomHash();
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CPPUNIT_TEST_SUITE(lru_map_test);
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CPPUNIT_TEST(testBaseUsage);
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CPPUNIT_TEST(testReplaceKey);
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CPPUNIT_TEST(testReplaceValue);
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CPPUNIT_TEST(testLruRemoval);
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CPPUNIT_TEST(testCustomHash);
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CPPUNIT_TEST_SUITE_END();
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};
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void lru_map_test::testBaseUsage()
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{
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o3tl::lru_map<int, int> lru(10);
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lru.insert(std::make_pair<int, int>(1, 1));
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std::pair<int, int> pair;
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for (int i = 2; i < 7; i++)
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{
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pair.first = pair.second = i;
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lru.insert(pair);
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}
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CPPUNIT_ASSERT_EQUAL(size_t(6), lru.size());
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o3tl::lru_map<int, int>::const_iterator it;
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it = lru.find(2);
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CPPUNIT_ASSERT(it != lru.end());
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CPPUNIT_ASSERT_EQUAL(2, it->second);
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it = lru.find(5);
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CPPUNIT_ASSERT(it != lru.end());
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CPPUNIT_ASSERT_EQUAL(5, it->second);
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it = lru.find(0);
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CPPUNIT_ASSERT(it == lru.end());
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}
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void lru_map_test::testReplaceValue()
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{
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o3tl::lru_map<int, int> lru(2);
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// check if map is empty
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CPPUNIT_ASSERT_EQUAL(size_t(0), lru.size());
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// check if inserting entry with with same key replaces the value
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// inserting new entry
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lru.insert(std::make_pair<int, int>(1, 2));
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CPPUNIT_ASSERT_EQUAL(size_t(1), lru.size());
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CPPUNIT_ASSERT_EQUAL(2, lru.find(1)->second);
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// inserting new entry with key that alreay exists
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lru.insert(std::make_pair<int, int>(1, 4));
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CPPUNIT_ASSERT_EQUAL(size_t(1), lru.size());
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CPPUNIT_ASSERT_EQUAL(4, lru.find(1)->second);
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// inserting new entry
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lru.insert(std::make_pair<int, int>(2, 200));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT_EQUAL(4, lru.find(1)->second);
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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// check if insert with same key, moves the entry back of the lru queu
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// inserting new entry with key that alreay exists
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lru.insert(std::make_pair<int, int>(1, 6));
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// inserting new entry, lru removed
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lru.insert(std::make_pair<int, int>(3, 300));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT_EQUAL(6, lru.find(1)->second);
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CPPUNIT_ASSERT_EQUAL(300, lru.find(3)->second);
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}
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void lru_map_test::testReplaceKey()
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{
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o3tl::lru_map<int, int> lru(2);
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// inserting new entry
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lru.insert(std::make_pair<int, int>(1, 100));
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CPPUNIT_ASSERT_EQUAL(size_t(1), lru.size());
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CPPUNIT_ASSERT_EQUAL(100, lru.find(1)->second);
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CPPUNIT_ASSERT(lru.find(2) == lru.end());
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CPPUNIT_ASSERT(lru.find(3) == lru.end());
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// inserting new entry
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lru.insert(std::make_pair<int, int>(2, 200));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT_EQUAL(100, lru.find(1)->second);
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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CPPUNIT_ASSERT(lru.find(3) == lru.end());
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// inserting new entry, lru entry is removed
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lru.insert(std::make_pair<int, int>(3, 300));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT(lru.find(1) == lru.end());
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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CPPUNIT_ASSERT_EQUAL(300, lru.find(3)->second);
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// inserting new entry, lru entry is removed
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std::pair<int, int> pair(4, 400);
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lru.insert(pair);
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT(lru.find(1) == lru.end());
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CPPUNIT_ASSERT(lru.find(2) == lru.end());
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CPPUNIT_ASSERT_EQUAL(300, lru.find(3)->second);
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CPPUNIT_ASSERT_EQUAL(400, lru.find(4)->second);
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}
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void lru_map_test::testLruRemoval()
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{
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o3tl::lru_map<int, int> lru(5);
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CPPUNIT_ASSERT_EQUAL(size_t(0), lru.size());
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// fill up..
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lru.insert(std::make_pair<int, int>(1, 100));
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lru.insert(std::make_pair<int, int>(2, 200));
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lru.insert(std::make_pair<int, int>(3, 300));
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lru.insert(std::make_pair<int, int>(4, 400));
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lru.insert(std::make_pair<int, int>(5, 500));
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CPPUNIT_ASSERT_EQUAL(size_t(5), lru.size());
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CPPUNIT_ASSERT_EQUAL(100, lru.find(1)->second);
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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CPPUNIT_ASSERT_EQUAL(300, lru.find(3)->second);
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CPPUNIT_ASSERT_EQUAL(400, lru.find(4)->second);
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CPPUNIT_ASSERT_EQUAL(500, lru.find(5)->second);
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// add one more entry - lru entry should be removed
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lru.insert(std::make_pair<int, int>(6, 600));
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CPPUNIT_ASSERT_EQUAL(size_t(5), lru.size());
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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CPPUNIT_ASSERT_EQUAL(300, lru.find(3)->second);
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CPPUNIT_ASSERT_EQUAL(400, lru.find(4)->second);
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CPPUNIT_ASSERT_EQUAL(500, lru.find(5)->second);
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CPPUNIT_ASSERT_EQUAL(600, lru.find(6)->second);
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// access the lru entry to put it at the back of the lru queue
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lru.find(2);
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// add new entry - lru entry should be removed
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lru.insert(std::make_pair<int, int>(7, 700));
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CPPUNIT_ASSERT_EQUAL(size_t(5), lru.size());
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CPPUNIT_ASSERT_EQUAL(200, lru.find(2)->second);
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CPPUNIT_ASSERT_EQUAL(400, lru.find(4)->second);
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CPPUNIT_ASSERT_EQUAL(500, lru.find(5)->second);
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CPPUNIT_ASSERT_EQUAL(600, lru.find(6)->second);
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CPPUNIT_ASSERT_EQUAL(700, lru.find(7)->second);
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}
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struct TestClassKey
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{
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int mA;
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int mB;
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TestClassKey(int a, int b)
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: mA(a)
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, mB(b)
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{}
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bool operator==(TestClassKey const& aOther) const
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{
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return mA == aOther.mA
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&& mB == aOther.mB;
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}
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};
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struct TestClassKeyHashFunction
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{
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std::size_t operator()(TestClassKey const& aKey) const
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{
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std::size_t seed = 0;
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boost::hash_combine(seed, aKey.mA);
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boost::hash_combine(seed, aKey.mB);
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return seed;
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}
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};
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void lru_map_test::testCustomHash()
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{
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// check lru_map with custom hash function
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o3tl::lru_map<TestClassKey, int, TestClassKeyHashFunction> lru(2);
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CPPUNIT_ASSERT_EQUAL(size_t(0), lru.size());
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lru.insert(std::make_pair<TestClassKey, int>(TestClassKey(1,1), 2));
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CPPUNIT_ASSERT_EQUAL(size_t(1), lru.size());
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lru.insert(std::make_pair<TestClassKey, int>(TestClassKey(1,1), 7));
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CPPUNIT_ASSERT_EQUAL(size_t(1), lru.size());
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lru.insert(std::make_pair<TestClassKey, int>(TestClassKey(1,2), 9));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT(lru.end() == lru.find(TestClassKey(0,0))); // non existent
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CPPUNIT_ASSERT_EQUAL(7, lru.find(TestClassKey(1,1))->second);
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CPPUNIT_ASSERT_EQUAL(9, lru.find(TestClassKey(1,2))->second);
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lru.insert(std::make_pair<TestClassKey, int>(TestClassKey(2,1), 13));
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CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
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CPPUNIT_ASSERT(lru.end() == lru.find(TestClassKey(1,1)));
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CPPUNIT_ASSERT_EQUAL(9, lru.find(TestClassKey(1,2))->second);
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CPPUNIT_ASSERT_EQUAL(13, lru.find(TestClassKey(2,1))->second);
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}
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CPPUNIT_TEST_SUITE_REGISTRATION(lru_map_test);
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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