修复AbstractCache.get中锁不一致导致的并发问题

hutool-core/src/main/java/org/dromara/hutool/core/cache/impl/AbstractCache.java

@@ -43,7 +43,7 @@ public abstract class AbstractCache<K, V> implements Cache<K, V> {
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * 缓存Map
+	 * 缓存Map。子类中初始化
 	 */
 	protected Map<Mutable<K>, CacheObj<K, V>> cacheMap;
 
@@ -145,12 +145,13 @@ public abstract class AbstractCache<K, V> implements Cache<K, V> {
 			keyLock.lock();
 			try {
 				// 双重检查锁，防止在竞争锁的过程中已经有其它线程写入
-				final CacheObj<K, V> co = getWithoutLock(key);
-				if (null == co || co.isExpired()) {
+				// issue#3686 由于这个方法内的加锁是get独立锁，不和put锁互斥，而put和pruneCache会修改cacheMap，导致在pruneCache过程中get会有并发问题
+				// 因此此处需要使用带全局锁的get获取值
+				v = get(key, isUpdateLastAccess);
+				if (null == v) {
+					// supplier的创建是一个耗时过程，此处创建与全局锁无关，而与key锁相关，这样就保证每个key只创建一个value，且互斥
 					v = supplier.get();
 					put(key, v, timeout);
-				} else {
-					v = co.get(isUpdateLastAccess);
 				}
 			} finally {
 				keyLock.unlock();

hutool-core/src/test/java/org/dromara/hutool/core/cache/Issue3686Test.java

@@ -0,0 +1,23 @@
+package org.dromara.hutool.core.cache;
+
+public class Issue3686Test {
+	public static void main(final String[] args) {
+//		final LRUCache<Long, Integer> objects = CacheUtil.newLRUCache(20, TimeUnit.SECONDS.toMillis(30));
+//		final List<Thread> list = new ArrayList<>();
+//		for (int i = 0; i < 10; i++) {
+//			final Thread thread = new Thread(() -> {
+//				while (true) {
+//					for (int i1 = 0; i1 < 100; i1++) {
+//						final int finalI = i1;
+//						objects.get((long) i1, () -> finalI);
+//					}
+//					ThreadUtil.sleep(500);
+//				}
+//			});
+//			list.add(thread);
+//		}
+//		for (final Thread thread : list) {
+//			thread.start();
+//		}
+	}
+}