HTTPCLIENT-2284: internal cache storage improvements (#478)

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

@@ -52,13 +52,13 @@
 @Contract(threading = ThreadingBehavior.SAFE)
 public class BasicHttpCacheStorage implements HttpCacheStorage {
 
-    private final CacheMap entries;
+    private final InternalCacheStorage entries;
 
     private final ReentrantLock lock;
 
     public BasicHttpCacheStorage(final CacheConfig config) {
         super();
-        this.entries = new CacheMap(config.getMaxCacheEntries());
+        this.entries = new InternalCacheStorage(config.getMaxCacheEntries(), null);
         this.lock = new ReentrantLock();
     }
 

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

@@ -0,0 +1,96 @@
+/*
+ * ====================================================================
+ * 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.impl.cache;
+
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.Map;
+import java.util.Queue;
+import java.util.function.Consumer;
+
+import org.apache.hc.client5.http.cache.HttpCacheEntry;
+import org.apache.hc.client5.http.cache.HttpCacheStorageEntry;
+import org.apache.hc.core5.annotation.Internal;
+
+@Internal
+final public class InternalCacheStorage {
+
+    private final Map<String, HttpCacheEntry> map;
+    private final Queue<HttpCacheStorageEntry> evictionQueue;
+    private final Consumer<HttpCacheStorageEntry> evictionCallback;
+
+    public InternalCacheStorage(final int maxEntries, final Consumer<HttpCacheStorageEntry> evictionCallback) {
+        this.evictionCallback = evictionCallback;
+        this.map = new LinkedHashMap<String, HttpCacheEntry>(20, 0.75f, true) {
+
+            @Override
+            protected boolean removeEldestEntry(final Map.Entry<String, HttpCacheEntry> eldest) {
+                if (size() > maxEntries) {
+                    if (evictionCallback != null) {
+                        evictionQueue.add(new HttpCacheStorageEntry(eldest.getKey(), eldest.getValue()));
+                    }
+                    return true;
+                } else {
+                    return false;
+                }
+            }
+
+        };
+        this.evictionQueue = new LinkedList<>();
+    }
+
+    public InternalCacheStorage(final int maxEntries) {
+        this(maxEntries, null);
+    }
+
+    public InternalCacheStorage() {
+        this(Integer.MAX_VALUE, null);
+    }
+
+    public void put(final String key, final HttpCacheEntry entry) {
+        map.put(key, entry);
+        HttpCacheStorageEntry evicted;
+        while ((evicted = evictionQueue.poll()) != null) {
+            if (evictionCallback != null) {
+                evictionCallback.accept(evicted);
+            }
+        }
+    }
+
+    public HttpCacheEntry get(final String key) {
+        return map.get(key);
+    }
+
+    public HttpCacheEntry remove(final String key) {
+        return map.remove(key);
+    }
+
+    public void clear() {
+        map.clear();
+    }
+
+}

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

@@ -78,7 +78,7 @@
 @Contract(threading = ThreadingBehavior.SAFE)
 public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
 
-    private final CacheMap entries;
+    private final InternalCacheStorage entries;
     private final ReferenceQueue<HttpCacheEntry> morque;
     private final Set<ResourceReference> resources;
     private final AtomicBoolean active;
@@ -87,7 +87,7 @@ public class ManagedHttpCacheStorage implements HttpCacheStorage, Closeable {
 
     public ManagedHttpCacheStorage(final CacheConfig config) {
         super();
-        this.entries = new CacheMap(config.getMaxCacheEntries());
+        this.entries = new InternalCacheStorage(config.getMaxCacheEntries(), null);
         this.morque = new ReferenceQueue<>();
         this.resources = new HashSet<>();
         this.active = new AtomicBoolean(true);

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

@@ -0,0 +1,97 @@
+/*
+ * ====================================================================
+ * 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.impl.cache;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+import org.apache.hc.client5.http.cache.HttpCacheEntry;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class TestInternalCacheStorage {
+
+    @Test
+    public void testCacheBasics() {
+        final InternalCacheStorage storage = new InternalCacheStorage();
+        final String key1 = "some-key-1";
+        Assertions.assertNull(storage.get(key1));
+        Assertions.assertNull(storage.remove(key1));
+        final HttpCacheEntry entry1 = HttpTestUtils.makeCacheEntry();
+        storage.put(key1, entry1);
+        Assertions.assertSame(entry1, storage.get(key1));
+        Assertions.assertSame(entry1, storage.remove(key1));
+        Assertions.assertNull(storage.get(key1));
+        Assertions.assertNull(storage.remove(key1));
+        final String key2 = "some-key-2";
+        final HttpCacheEntry entry2 = HttpTestUtils.makeCacheEntry();
+        final String key3 = "some-key-3";
+        final HttpCacheEntry entry3 = HttpTestUtils.makeCacheEntry();
+        storage.put(key2, entry2);
+        storage.put(key3, entry3);
+        Assertions.assertSame(entry2, storage.get(key2));
+        Assertions.assertSame(entry3, storage.get(key3));
+        storage.clear();
+        Assertions.assertNull(storage.get(key2));
+        Assertions.assertNull(storage.get(key3));
+    }
+
+    @Test
+    public void testCacheEviction() {
+        final Queue<HttpCacheEntry> evictedEntries = new LinkedList<>();
+        final InternalCacheStorage storage = new InternalCacheStorage(2, e -> evictedEntries.add(e.getContent()));
+        final String key1 = "some-key-1";
+        final String key2 = "some-key-2";
+        final String key3 = "some-key-3";
+        final String key4 = "some-key-4";
+        final HttpCacheEntry entry1 = HttpTestUtils.makeCacheEntry();
+        final HttpCacheEntry entry2 = HttpTestUtils.makeCacheEntry();
+        final HttpCacheEntry entry3 = HttpTestUtils.makeCacheEntry();
+        final HttpCacheEntry entry4 = HttpTestUtils.makeCacheEntry();
+
+        storage.put(key1, entry1);
+        storage.put(key2, entry2);
+        storage.put(key3, entry3);
+        storage.put(key4, entry4);
+        Assertions.assertSame(entry1, evictedEntries.poll());
+        Assertions.assertSame(entry2, evictedEntries.poll());
+        Assertions.assertNull(evictedEntries.poll());
+
+        storage.clear();
+        storage.put(key1, entry1);
+        storage.put(key2, entry2);
+        storage.get(key1);
+        storage.put(key3, entry3);
+        storage.get(key1);
+        storage.put(key4, entry4);
+
+        Assertions.assertSame(entry2, evictedEntries.poll());
+        Assertions.assertSame(entry3, evictedEntries.poll());
+        Assertions.assertNull(evictedEntries.poll());
+    }
+
+}