/*
 * Copyright 2014-2016 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.amqp.rabbit.core.support;

import java.util.Collection;
import java.util.Date;

import org.springframework.amqp.core.Message;

/**
 * Strategy for batching messages. The methods will never be called concurrently.
 * <p>
 * <b>Experimental - APIs may change.</b>
 *
 * @author Gary Russell
 * @since 1.4.1
 *
 */
public interface BatchingStrategy {

	/**
	 * Add a message to the batch and optionally release the batch.
	 * @param exchange The exchange.
	 * @param routingKey The routing key.
	 * @param message The message.
	 * @return The batched message ({@link MessageBatch}), or null if not ready to release.
	 */
	MessageBatch addToBatch(String exchange, String routingKey, Message message);

	/**
	 * @return the date the next scheduled release should run, or null if no data to release.
	 */
	Date nextRelease();

	/**
	 * Release batch(es), perhaps due to a timeout.
	 * @return The batched message(s).
	 */
	Collection<MessageBatch> releaseBatches();

}