116 lines
4.3 KiB
Java
116 lines
4.3 KiB
Java
package com.yunhai.cms.config;
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import com.github.benmanes.caffeine.cache.Caffeine;
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import com.github.benmanes.caffeine.cache.Expiry;
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import org.springframework.cache.CacheManager;
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import org.springframework.cache.annotation.CachingConfigurer;
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import org.springframework.cache.annotation.EnableCaching;
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import org.springframework.cache.caffeine.CaffeineCache;
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import org.springframework.cache.interceptor.CacheErrorHandler;
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import org.springframework.cache.support.SimpleCacheManager;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.lang.NonNull;
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import java.time.Duration;
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import java.util.Arrays;
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import java.util.concurrent.ThreadLocalRandom;
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/**
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* Caffeine 本地缓存装配（方案 §8.4 工程约束）。
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*
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* <ul>
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* <li>TTL 随机抖动 ±60s 防雪崩：自定义 {@link JitterExpiry} 按条目随机；</li>
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* <li>null 哨兵 30s 防穿透（爬虫扫随机 ID）：写入值为 Spring NullValue 标记时短 TTL；</li>
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* <li>CacheErrorHandler：缓存异常按 miss 降级 + error 日志（dirty data risk, TTL 自愈）。</li>
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* </ul>
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* 切 Redis 时仅替换本配置与 spring.cache.type（方案 §1.2/§12）；
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* yml 中 spring.cache.caffeine.spec 供默认管理器/演进期使用，本管理器按 CacheNames 显式装配。
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*/
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@Configuration
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@EnableCaching
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public class CacheConfig implements CachingConfigurer {
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/** 抖动幅度：±60s */
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private static final Duration JITTER = Duration.ofSeconds(60);
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/** null 哨兵 TTL */
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private static final Duration NULL_TTL = Duration.ofSeconds(30);
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/** 抖动后 TTL 下限，避免抖出负数/过短 */
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private static final Duration MIN_TTL = Duration.ofSeconds(30);
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private final LoggingCacheErrorHandler errorHandler;
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public CacheConfig(LoggingCacheErrorHandler errorHandler) {
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this.errorHandler = errorHandler;
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}
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@Bean
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@Override
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public CacheManager cacheManager() {
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SimpleCacheManager manager = new SimpleCacheManager();
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manager.setCaches(Arrays.asList(
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new CaffeineCache(CacheNames.SITE, caffeine(Duration.ofMinutes(30)).build()),
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new CaffeineCache(CacheNames.ARTICLE, caffeine(Duration.ofMinutes(5)).build()),
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new CaffeineCache(CacheNames.LIST, caffeine(Duration.ofMinutes(5)).build())));
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return manager;
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}
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@Override
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public CacheErrorHandler errorHandler() {
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return errorHandler;
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}
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private Caffeine<Object, Object> caffeine(Duration baseTtl) {
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return Caffeine.newBuilder()
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.maximumSize(10_000)
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.expireAfter(new JitterExpiry(baseTtl));
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}
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/**
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* 按 TTL 基准 + 随机抖动的过期策略；null 哨兵固定 30s。
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*/
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static class JitterExpiry implements Expiry<Object, Object> {
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private final Duration baseTtl;
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JitterExpiry(Duration baseTtl) {
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this.baseTtl = baseTtl;
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}
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@Override
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public long expireAfterCreate(@NonNull Object key, Object value, long currentTime) {
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if (isNullValue(value)) {
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return NULL_TTL.toNanos();
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}
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long jitterMillis = ThreadLocalRandom.current()
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.nextLong(-JITTER.toMillis(), JITTER.toMillis());
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Duration jittered = baseTtl.plusMillis(jitterMillis);
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if (jittered.compareTo(MIN_TTL) < 0) {
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jittered = MIN_TTL;
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}
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return jittered.toNanos();
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}
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@Override
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public long expireAfterUpdate(@NonNull Object key, Object value, long currentTime,
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long currentDuration) {
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return currentDuration;
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}
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@Override
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public long expireAfterRead(@NonNull Object key, Object value, long currentTime,
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long currentDuration) {
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return currentDuration;
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}
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/**
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* Spring 把 null 包成 NullValue 单例存入 Caffeine（Caffeine 本身不收 null）。
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* 用类名判断避免对 Spring 内部类硬编译依赖。
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*/
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private boolean isNullValue(Object value) {
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return value == null
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|| "org.springframework.cache.support.NullValue".equals(value.getClass().getName());
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}
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}
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}
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