| /* |
| * 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. |
| */ |
| package org.apache.qpid.protonj2.client.util; |
| |
| import java.util.ArrayDeque; |
| import java.util.Deque; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicIntegerFieldUpdater; |
| |
| import org.apache.qpid.protonj2.client.Delivery; |
| import org.apache.qpid.protonj2.client.impl.ClientDelivery; |
| |
| /** |
| * Simple first in / first out {@link Delivery} Queue. |
| */ |
| public final class FifoDeliveryQueue implements DeliveryQueue { |
| |
| private static final AtomicIntegerFieldUpdater<FifoDeliveryQueue> STATE_FIELD_UPDATER = |
| AtomicIntegerFieldUpdater.newUpdater(FifoDeliveryQueue.class, "state"); |
| |
| private static final int CLOSED = 0; |
| private static final int STOPPED = 1; |
| private static final int RUNNING = 2; |
| |
| private volatile int state = STOPPED; |
| |
| private final Deque<ClientDelivery> queue; |
| |
| /** |
| * Creates a new first in / first out message queue with the given queue depth |
| * |
| * @param queueDepth |
| * The Queue depth to configure for this FIFO Message Queue. |
| */ |
| public FifoDeliveryQueue(int queueDepth) { |
| this.queue = new ArrayDeque<ClientDelivery>(Math.max(1, queueDepth)); |
| } |
| |
| @Override |
| public void enqueueFirst(ClientDelivery envelope) { |
| synchronized (queue) { |
| queue.addFirst(envelope); |
| queue.notify(); |
| } |
| } |
| |
| @Override |
| public void enqueue(ClientDelivery envelope) { |
| synchronized (queue) { |
| queue.addLast(envelope); |
| queue.notify(); |
| } |
| } |
| |
| @Override |
| public ClientDelivery dequeue(long timeout) throws InterruptedException { |
| synchronized (queue) { |
| // Wait until the receiver is ready to deliver messages. |
| while (timeout != 0 && isRunning() && queue.isEmpty()) { |
| if (timeout == -1) { |
| queue.wait(); |
| } else { |
| long start = System.currentTimeMillis(); |
| queue.wait(TimeUnit.MILLISECONDS.toMillis(timeout)); |
| timeout = Math.max(timeout + start - System.currentTimeMillis(), 0); |
| } |
| } |
| |
| if (!isRunning()) { |
| return null; |
| } |
| |
| return queue.pollFirst(); |
| } |
| } |
| |
| @Override |
| public ClientDelivery dequeueNoWait() { |
| synchronized (queue) { |
| if (!isRunning()) { |
| return null; |
| } |
| |
| return queue.pollFirst(); |
| } |
| } |
| |
| @Override |
| public void start() { |
| if (STATE_FIELD_UPDATER.compareAndSet(this, STOPPED, RUNNING)) { |
| synchronized (queue) { |
| queue.notifyAll(); |
| } |
| } |
| } |
| |
| @Override |
| public void stop() { |
| if (STATE_FIELD_UPDATER.compareAndSet(this, RUNNING, STOPPED)) { |
| synchronized (queue) { |
| queue.notifyAll(); |
| } |
| } |
| } |
| |
| @Override |
| public void close() { |
| if (STATE_FIELD_UPDATER.getAndSet(this, CLOSED) > CLOSED) { |
| synchronized (queue) { |
| queue.notifyAll(); |
| } |
| } |
| } |
| |
| @Override |
| public boolean isRunning() { |
| return state == RUNNING; |
| } |
| |
| @Override |
| public boolean isClosed() { |
| return state == CLOSED; |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| synchronized (queue) { |
| return queue.isEmpty(); |
| } |
| } |
| |
| @Override |
| public int size() { |
| synchronized (queue) { |
| return queue.size(); |
| } |
| } |
| |
| @Override |
| public void clear() { |
| synchronized (queue) { |
| queue.clear(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| synchronized (queue) { |
| return queue.toString(); |
| } |
| } |
| } |