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https://github.com/tiennm99/zfoo.git
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del[cache]: delete SimpleCache
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godotg
@@ -1,191 +0,0 @@
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/*
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* Copyright (C) 2020 The zfoo Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed
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* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and limitations under the License.
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*/
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package com.zfoo.net.util;
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import com.github.benmanes.caffeine.cache.CacheLoader;
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import com.github.benmanes.caffeine.cache.Caffeine;
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import com.github.benmanes.caffeine.cache.LoadingCache;
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import com.zfoo.event.manager.EventBus;
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import com.zfoo.protocol.collection.CollectionUtils;
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import com.zfoo.protocol.model.Pair;
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import com.zfoo.scheduler.manager.SchedulerBus;
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import org.checkerframework.checker.nullness.qual.NonNull;
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import org.checkerframework.checker.nullness.qual.Nullable;
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import java.util.*;
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import java.util.concurrent.ConcurrentLinkedQueue;
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import java.util.concurrent.TimeUnit;
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import java.util.function.Function;
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/**
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* caffeine是guava cache的威力增强版。
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* caffeine的缓存都是单个存，单个更新，但是实际的项目很多都是批量查询，批量更新。
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* <p>
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* 优势：
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* 1.支持批量查找，批量更新。
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* 2.可以防止缓存穿透，缓存击穿，缓存雪崩
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* <p>
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* 批量查找通过batchLoadCallback方法查找，当查找的key不存在的时候，调用defaultValueBuilder生成一个默认值放入缓存。
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*
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* @author godotg
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*/
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public class SimpleCache<K, V> {
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/**
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* 每次最多更新1000条数据
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*/
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private static final int BATCH_RELOAD_SIZE = 1000;
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private LoadingCache<K, V> cache;
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private ConcurrentLinkedQueue<K> linkedQueue;
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private long expiredAccessDuration;
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private long refreshDuration;
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private Function<List<K>, List<Pair<K, V>>> batchLoadCallback;
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private Function<K, V> defaultValueBuilder;
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/**
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* @param expiredAccessDuration 访问过期时间，毫秒；通常情况下，这个值比refreshDuration大会得到更好的缓存效果，一般是2倍
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* @param refreshDuration 刷新实际那，毫秒；因为是通过后台scheduler去更新缓存，所以更新的refresh可能是这个值的2倍
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* @param maxSize 缓存大小
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* @param batchLoadCallback 一组key取value的回调方法
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* @param defaultValueBuilder 默认值构建
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* @return 简单的缓存
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*/
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public static <K, V> SimpleCache<K, V> build(long expiredAccessDuration, long refreshDuration, long maxSize
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, Function<List<K>, List<Pair<K, V>>> batchLoadCallback
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, Function<K, V> defaultValueBuilder) {
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var linkedQueue = new ConcurrentLinkedQueue<K>();
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// 没有用expireAfterWrite的原因是容易造成缓存击穿
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var cache = Caffeine.newBuilder()
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.expireAfterAccess(expiredAccessDuration, TimeUnit.MILLISECONDS)
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.refreshAfterWrite(refreshDuration, TimeUnit.MILLISECONDS)
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.maximumSize(maxSize)
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.recordStats()
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.build(new CacheLoader<K, V>() {
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@Override
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public @Nullable V load(@NonNull K key) {
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var resultList = batchLoadCallback.apply(List.of(key));
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return CollectionUtils.isEmpty(resultList) ? defaultValueBuilder.apply(key) : resultList.get(0).getValue();
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}
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@Override
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public @Nullable V reload(@NonNull K key, @NonNull V oldValue) {
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// 将待刷新的缓存放入队列，等Scheduler周期任务批量刷新老的缓存值
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linkedQueue.offer(key);
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// 先返回老的值
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return oldValue;
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}
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});
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SchedulerBus.scheduleAtFixedRate(() -> {
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// 不在任务调度线程中执行耗时任务，因为任务调度线程只有一个线程池
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EventBus.asyncExecute(() -> {
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var list = new ArrayList<K>();
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while (!linkedQueue.isEmpty()) {
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var key = linkedQueue.poll();
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list.add(key);
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if (list.size() >= BATCH_RELOAD_SIZE) {
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var result = batchLoadCallback.apply(list);
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result.forEach(it -> cache.put(it.getKey(), it.getValue()));
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list.clear();
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}
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}
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if (CollectionUtils.isNotEmpty(list)) {
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var result = batchLoadCallback.apply(list);
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result.forEach(it -> cache.put(it.getKey(), it.getValue()));
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}
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});
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}, refreshDuration, TimeUnit.MILLISECONDS);
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var simpleCache = new SimpleCache<K, V>();
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simpleCache.cache = cache;
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simpleCache.linkedQueue = linkedQueue;
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simpleCache.expiredAccessDuration = expiredAccessDuration;
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simpleCache.refreshDuration = refreshDuration;
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simpleCache.batchLoadCallback = batchLoadCallback;
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simpleCache.defaultValueBuilder = defaultValueBuilder;
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return simpleCache;
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}
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/**
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* 单个查找
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*/
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public V get(K k) {
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try {
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return cache.get(k);
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} catch (Exception e) {
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var defaultValue = defaultValueBuilder.apply(k);
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cache.put(k, defaultValue);
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return defaultValue;
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}
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}
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/**
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* 异步刷新缓存
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*/
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public void invalidate(K k) {
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cache.invalidate(k);
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}
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public void put(K k, V v) {
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cache.put(k, v);
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}
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/**
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* 批量查找
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*/
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public Map<K, V> batchGet(Collection<K> list) {
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if (CollectionUtils.isEmpty(list)) {
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return Collections.emptyMap();
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}
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var result = new HashMap<K, V>();
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var notPresentIdSet = new HashSet<K>();
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for (var id : list) {
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var value = cache.getIfPresent(id);
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if (value != null) {
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result.put(id, value);
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} else {
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notPresentIdSet.add(id);
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}
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}
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if (CollectionUtils.isNotEmpty(notPresentIdSet)) {
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batchLoadCallback.apply(new ArrayList<>(notPresentIdSet))
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.forEach(it -> {
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result.put(it.getKey(), it.getValue());
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cache.put(it.getKey(), it.getValue());
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notPresentIdSet.remove(it.getKey());
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});
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}
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// 防止缓存穿透，将数据库查询不到的键存入到缓存，value给一个默认值
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if (CollectionUtils.isNotEmpty(notPresentIdSet)) {
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notPresentIdSet.forEach(it -> {
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var defaultValue = defaultValueBuilder.apply(it);
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result.put(it, defaultValue);
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cache.put(it, defaultValue);
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});
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}
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return result;
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}
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}
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@@ -1,55 +0,0 @@
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/*
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* Copyright (C) 2020 The zfoo Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed
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* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and limitations under the License.
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*/
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package com.zfoo.net.util;
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import com.zfoo.protocol.model.Pair;
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import com.zfoo.protocol.util.ThreadUtils;
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import org.junit.Ignore;
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import org.junit.Test;
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import java.util.List;
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import java.util.function.Function;
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/**
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* @author godotg
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*/
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@Ignore
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public class SimpleCacheTest {
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@Test
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public void test() {
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var cache = SimpleCache.build(3000, 6000, 100, new Function<List<String>, List<Pair<String, String>>>() {
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@Override
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public List<Pair<String, String>> apply(List<String> keyList) {
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return keyList.stream().map(it -> new Pair<>(it, "new-" + it + "-value")).toList();
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}
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}, key -> "empty");
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cache.put("a", "b");
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cache.get("a");
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ThreadUtils.sleep(3000);
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System.out.println(cache.get("a"));
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ThreadUtils.sleep(1000);
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System.out.println(cache.get("a"));
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ThreadUtils.sleep(1000);
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System.out.println(cache.get("a"));
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ThreadUtils.sleep(1000);
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System.out.println(cache.get("a"));
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ThreadUtils.sleep(1000);
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System.out.println(cache.get("a"));
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ThreadUtils.sleep(Long.MAX_VALUE);
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}
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}
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