Expose method to check the cache is still active.

httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/ManagedHttpCacheStorage.java

@@ -91,7 +91,7 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
     }
 
     private void ensureValidState() {
-        if (!this.active.get()) {
+        if (!isActive()) {
             throw new IllegalStateException("Cache has been shut down");
         }
     }
@@ -167,7 +167,7 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
     }
 
     public void cleanResources() {
-        if (this.active.get()) {
+        if (isActive()) {
             ResourceReference ref;
             while ((ref = (ResourceReference) this.morque.poll()) != null) {
                 synchronized (this) {
@@ -179,7 +179,7 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
     }
 
     public void shutdown() {
-        if (this.active.compareAndSet(true, false)) {
+        if (compareAndSet()) {
             synchronized (this) {
                 this.entries.clear();
                 for (final ResourceReference ref: this.resources) {
@@ -194,7 +194,7 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
 
     @Override
     public void close() {
-        if (this.active.compareAndSet(true, false)) {
+        if (compareAndSet()) {
             synchronized (this) {
                 ResourceReference ref;
                 while ((ref = (ResourceReference) this.morque.poll()) != null) {
@@ -205,4 +205,17 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
         }
     }
 
+    /**
+     * Check if the cache is still active and has not shut down.
+     *
+     * @return {@code true} if the cache is active, otherwise return {@code false}.
+     * @since 5.2
+     */
+    public boolean isActive() {
+        return active.get();
+    }
+
+    private boolean compareAndSet(){
+        return this.active.compareAndSet(true, false);
+    }
 }

httpclient5-cache/src/test/java/org/apache/hc/client5/http/cache/ManagedHttpCacheStorageTest.java

@@ -0,0 +1,84 @@
+/*
+ * ====================================================================
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+package org.apache.hc.client5.http.cache;
+
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.apache.hc.client5.http.impl.cache.CacheConfig;
+import org.apache.hc.client5.http.impl.cache.HttpTestUtils;
+import org.apache.hc.client5.http.impl.cache.ManagedHttpCacheStorage;
+import org.apache.hc.core5.http.HttpStatus;
+import org.junit.jupiter.api.Test;
+
+class ManagedHttpCacheStorageTest {
+
+    @Test
+    void putEntry() throws ResourceIOException {
+
+        final CacheConfig cacheConfig = getCacheConfig();
+        final ManagedHttpCacheStorage cacheStorage = new ManagedHttpCacheStorage(cacheConfig);
+        final String key = "foo";
+        final HttpCacheEntry value = HttpTestUtils.makeCacheEntry();
+        cacheStorage.putEntry(key, value);
+        assertEquals(HttpStatus.SC_OK, cacheStorage.getEntry(key).getStatus());
+    }
+
+    @Test
+    void isActive() throws ResourceIOException {
+
+        final CacheConfig cacheConfig = getCacheConfig();
+        final ManagedHttpCacheStorage cacheStorage = new ManagedHttpCacheStorage(cacheConfig);
+        final String key = "foo";
+        final HttpCacheEntry value = HttpTestUtils.makeCacheEntry();
+        cacheStorage.putEntry(key, value);
+        assertTrue(cacheStorage.isActive());
+        cacheStorage.close();
+        assertFalse(cacheStorage.isActive());
+    }
+
+    @Test
+    void cacheDisableThrowsIllegalStateException() {
+        final CacheConfig cacheConfig = getCacheConfig();
+        final ManagedHttpCacheStorage cacheStorage = new ManagedHttpCacheStorage(cacheConfig);
+        final String key = "foo";
+        final HttpCacheEntry value = HttpTestUtils.makeCacheEntry();
+        cacheStorage.close();
+        assertFalse(cacheStorage.isActive());
+        assertThrows(IllegalStateException.class, () -> cacheStorage.putEntry(key, value));
+    }
+
+    private CacheConfig getCacheConfig() {
+        return CacheConfig.custom()
+                .setSharedCache(true)
+                .setMaxObjectSize(262144) //256kb
+                .build();
+    }
+}