Added QueueRepository implemented in memory and on H2

broker/src/main/java/io/moquette/persistence/H2Builder.java

@@ -1,6 +1,7 @@
 package io.moquette.persistence;
 
 import io.moquette.BrokerConstants;
+import io.moquette.broker.IQueueRepository;
 import io.moquette.broker.ISubscriptionsRepository;
 import io.moquette.broker.config.IConfig;
 import org.h2.mvstore.MVStore;
@@ -52,4 +53,8 @@ public class H2Builder {
     public void closeStore() {
         mvStore.close();
     }
+
+    public IQueueRepository queueRepository() {
+        return new H2QueueRepository(mvStore);
+    }
 }

broker/src/main/java/io/moquette/persistence/H2PersistentQueue.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2012-2018 The original author or authors
+ * ------------------------------------------------------
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Apache License v2.0 which accompanies this distribution.
+ *
+ * The Eclipse Public License is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * The Apache License v2.0 is available at
+ * http://www.opensource.org/licenses/apache2.0.php
+ *
+ * You may elect to redistribute this code under either of these licenses.
+ */
+package io.moquette.persistence;
+
+import org.h2.mvstore.MVMap;
+import org.h2.mvstore.MVStore;
+
+import java.util.AbstractQueue;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicLong;
+
+class H2PersistentQueue<T> extends AbstractQueue<T> {
+
+    private final MVMap<Long, T> queueMap;
+    private final MVMap<String, Long> metadataMap;
+    private final AtomicLong head;
+    private final AtomicLong tail;
+
+    H2PersistentQueue(MVStore store, String queueName) {
+        if (queueName == null || queueName.isEmpty()) {
+            throw new IllegalArgumentException("queueName parameter can't be empty or null");
+        }
+        this.queueMap = store.openMap("queue_" + queueName);
+        this.metadataMap = store.openMap("queue_" + queueName + "_meta");
+
+        //setup head index
+        long headIdx = 0L;
+        if (this.metadataMap.containsKey("head")) {
+            headIdx = this.metadataMap.get("head");
+        } else {
+            this.metadataMap.put("head", headIdx);
+        }
+        this.head = new AtomicLong(headIdx);
+
+        //setup tail index
+        long tailIdx = 0L;
+        if (this.metadataMap.containsKey("tail")) {
+            tailIdx = this.metadataMap.get("tail");
+        } else {
+            this.metadataMap.put("tail", tailIdx);
+        }
+        this.tail = new AtomicLong(tailIdx);
+    }
+
+    static void dropQueue(MVStore store, String queueName) {
+        store.removeMap(store.openMap("queue_" + queueName));
+        store.removeMap(store.openMap("queue_" + queueName + "_meta"));
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return this.head.intValue() - this.tail.intValue();
+    }
+
+    @Override
+    public boolean offer(T t) {
+        if (t == null) {
+            throw new NullPointerException("Inserted element can't be null");
+        }
+        final long nextHead = head.getAndIncrement();
+        this.queueMap.put(nextHead, t);
+        this.metadataMap.put("head", nextHead + 1);
+        return true;
+    }
+
+    @Override
+    public T poll() {
+        if (head.equals(tail)) {
+            return null;
+        }
+        final long nextTail = tail.getAndIncrement();
+        final T tail = this.queueMap.get(nextTail);
+        queueMap.remove(nextTail);
+        this.metadataMap.put("tail", nextTail + 1);
+        return tail;
+    }
+
+    @Override
+    public T peek() {
+        if (head.equals(tail)) {
+            return null;
+        }
+        return this.queueMap.get(tail.get());
+    }
+
+}

broker/src/main/java/io/moquette/persistence/H2QueueRepository.java

@@ -0,0 +1,25 @@
+package io.moquette.persistence;
+
+import io.moquette.broker.IQueueRepository;
+import io.moquette.broker.SessionRegistry;
+import org.h2.mvstore.MVStore;
+
+import java.util.Queue;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+public class H2QueueRepository implements IQueueRepository {
+
+    private MVStore mvStore;
+
+    public H2QueueRepository(MVStore mvStore) {
+        this.mvStore = mvStore;
+    }
+
+    @Override
+    public Queue<SessionRegistry.EnqueuedMessage> createQueue(String cli, boolean clean) {
+        if (!clean) {
+            return new H2PersistentQueue<>(mvStore, cli);
+        }
+        return new ConcurrentLinkedQueue<>();
+    }
+}