MessageCounterHandler.java

/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed 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.springframework.xd.analytics.metrics.integration;

import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.messaging.Message;
import org.springframework.util.Assert;
import org.springframework.xd.analytics.metrics.core.CounterRepository;

/**
 * Counts the number of non-null messages using an underlying {@link CounterRepository}.
 *
 */
public class MessageCounterHandler extends AbstractMetricHandler {

	private final CounterRepository counterRepository;

	public MessageCounterHandler(CounterRepository counterRepository, String nameExpression) {
		super(nameExpression);
		Assert.notNull(counterRepository, "Counter Repository can not be null");
		this.counterRepository = counterRepository;
	}

	@ServiceActivator
	public Message<?> process(Message<?> message) {
		if (message != null) {
			this.counterRepository.increment(computeMetricName(message));
		}
		return message;
	}

}