SedaComponent.java

/**
 * 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.camel.component.seda;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.BlockingQueue;

import org.apache.camel.Component;
import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.impl.UriEndpointComponent;
import org.apache.camel.spi.Metadata;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The <a href="http://camel.apache.org/seda.html">SEDA Component</a> is for asynchronous SEDA exchanges on a {@link BlockingQueue} within a CamelContext
 *
 * @version 
 */
public class SedaComponent extends UriEndpointComponent {
    protected final Logger log = LoggerFactory.getLogger(getClass());
    protected final int maxConcurrentConsumers = 500;
    @Metadata(label = "advanced")
    protected int queueSize;
    @Metadata(label = "consumer", defaultValue = "1")
    protected int concurrentConsumers = 1;
    private final Map<String, QueueReference> queues = new HashMap<String, QueueReference>();
    @Metadata(label = "advanced")
    private BlockingQueueFactory<Exchange> defaultQueueFactory = new LinkedBlockingQueueFactory<Exchange>();

    public SedaComponent() {
        super(SedaEndpoint.class);
    }

    public SedaComponent(Class<? extends Endpoint> endpointClass) {
        super(endpointClass);
    }

    /**
     * Sets the default maximum capacity of the SEDA queue (i.e., the number of messages it can hold).
     */
    public void setQueueSize(int size) {
        queueSize = size;
    }
    
    public int getQueueSize() {
        return queueSize;
    }

    /**
     * Sets the default number of concurrent threads processing exchanges.
     */
    public void setConcurrentConsumers(int size) {
        concurrentConsumers = size;
    }
    
    public int getConcurrentConsumers() {
        return concurrentConsumers;
    }

    public BlockingQueueFactory<Exchange> getDefaultQueueFactory() {
        return defaultQueueFactory;
    }

    /**
     * Sets the default queue factory.
     */
    public void setDefaultQueueFactory(BlockingQueueFactory<Exchange> defaultQueueFactory) {
        this.defaultQueueFactory = defaultQueueFactory;
    }

    /**
     * @deprecated use
     */
    @Deprecated
    public synchronized QueueReference getOrCreateQueue(SedaEndpoint endpoint, Integer size) {
        return getOrCreateQueue(endpoint, size, null);
    }

    /**
     * @deprecated use {@link #getOrCreateQueue(SedaEndpoint, Integer, Boolean, BlockingQueueFactory)}
     */
    @Deprecated
    public synchronized QueueReference getOrCreateQueue(SedaEndpoint endpoint, Integer size, Boolean multipleConsumers) {
        return getOrCreateQueue(endpoint, size, multipleConsumers, null);
    }

    public synchronized QueueReference getOrCreateQueue(SedaEndpoint endpoint, Integer size, Boolean multipleConsumers, BlockingQueueFactory<Exchange> customQueueFactory) {
        String key = getQueueKey(endpoint.getEndpointUri());

        QueueReference ref = getQueues().get(key);
        if (ref != null) {

            // if the given size is not provided, we just use the existing queue as is
            if (size != null && !size.equals(ref.getSize())) {
                // there is already a queue, so make sure the size matches
                throw new IllegalArgumentException("Cannot use existing queue " + key + " as the existing queue size "
                        + (ref.getSize() != null ? ref.getSize() : Integer.MAX_VALUE) + " does not match given queue size " + size);
            }
            // add the reference before returning queue
            ref.addReference(endpoint);

            if (log.isDebugEnabled()) {
                log.debug("Reusing existing queue {} with size {} and reference count {}", new Object[]{key, size, ref.getCount()});
            }
            return ref;
        }

        // create queue
        BlockingQueue<Exchange> queue;
        BlockingQueueFactory<Exchange> queueFactory = customQueueFactory == null ? defaultQueueFactory : customQueueFactory;
        if (size != null && size > 0) {
            queue = queueFactory.create(size);
        } else {
            if (getQueueSize() > 0) {
                size = getQueueSize();
                queue = queueFactory.create(getQueueSize());
            } else {
                queue = queueFactory.create();
            }
        }
        log.debug("Created queue {} with size {}", key, size);

        // create and add a new reference queue
        ref = new QueueReference(queue, size, multipleConsumers);
        ref.addReference(endpoint);
        getQueues().put(key, ref);

        return ref;
    }

    public synchronized QueueReference registerQueue(SedaEndpoint endpoint, BlockingQueue<Exchange> queue) {
        String key = getQueueKey(endpoint.getEndpointUri());

        QueueReference ref = getQueues().get(key);
        if (ref == null) {
            ref = new QueueReference(queue, endpoint.getSize(), endpoint.isMultipleConsumers());
            ref.addReference(endpoint);
            getQueues().put(key, ref);
        }

        return ref;
    }

    public Map<String, QueueReference> getQueues() {
        return queues;
    }

    public QueueReference getQueueReference(String key) {
        return queues.get(key);
    }

    @Override
    @SuppressWarnings("unchecked")
    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
        int consumers = getAndRemoveParameter(parameters, "concurrentConsumers", Integer.class, concurrentConsumers);
        boolean limitConcurrentConsumers = getAndRemoveParameter(parameters, "limitConcurrentConsumers", Boolean.class, true);
        if (limitConcurrentConsumers && consumers >  maxConcurrentConsumers) {
            throw new IllegalArgumentException("The limitConcurrentConsumers flag in set to true. ConcurrentConsumers cannot be set at a value greater than "
                    + maxConcurrentConsumers + " was " + consumers);
        }

        // Resolve queue reference
        BlockingQueue<Exchange> queue = resolveAndRemoveReferenceParameter(parameters, "queue", BlockingQueue.class);
        SedaEndpoint answer;
        // Resolve queue factory when no queue specified
        if (queue == null) {
            BlockingQueueFactory<Exchange> queueFactory = resolveAndRemoveReferenceParameter(parameters, "queueFactory", BlockingQueueFactory.class);
            // defer creating queue till endpoint is started, so we pass the queue factory
            answer = createEndpoint(uri, this, queueFactory, consumers);
        } else {
            answer = createEndpoint(uri, this, queue, consumers);
        }
        answer.configureProperties(parameters);
        answer.setConcurrentConsumers(consumers);
        answer.setLimitConcurrentConsumers(limitConcurrentConsumers);
        return answer;
    }

    protected SedaEndpoint createEndpoint(String endpointUri, Component component, BlockingQueueFactory<Exchange> queueFactory, int concurrentConsumers) {
        return new SedaEndpoint(endpointUri, component, queueFactory, concurrentConsumers);
    }

    protected SedaEndpoint createEndpoint(String endpointUri, Component component, BlockingQueue<Exchange> queue, int concurrentConsumers) {
        return new SedaEndpoint(endpointUri, component, queue, concurrentConsumers);
    }

    public String getQueueKey(String uri) {
        if (uri.contains("?")) {
            // strip parameters
            uri = uri.substring(0, uri.indexOf('?'));
        }
        return uri;
    }

    @Override
    protected void doStop() throws Exception {
        getQueues().clear();
        super.doStop();
    }

    /**
     * On shutting down the endpoint
     * 
     * @param endpoint the endpoint
     */
    void onShutdownEndpoint(SedaEndpoint endpoint) {
        // we need to remove the endpoint from the reference counter
        String key = getQueueKey(endpoint.getEndpointUri());
        QueueReference ref = getQueues().get(key);
        if (ref != null && endpoint.getConsumers().size() == 0) {
            // only remove the endpoint when the consumers are removed
            ref.removeReference(endpoint);
            if (ref.getCount() <= 0) {
                // reference no longer needed so remove from queues
                getQueues().remove(key);
            }
        }
    }

}