CompoundTriggerAdvice for Smart Polling with Spring Integration

CompoundTrigger.java

/*
 * Copyright 2015 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 example;

import java.util.Date;

import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.TriggerContext;

import reactor.core.support.Assert;

/**
 * @author Gary Russell
 * @since 4.3
 *
 */
public class CompoundTrigger implements Trigger {

	private volatile Trigger primary;

	private volatile Trigger override;

	/**
	 * Construct a compound trigger with the supplied primary trigger.
	 * @param primary the primary trigger.
	 */
	public CompoundTrigger(Trigger primary) {
		setPrimary(primary);
	}

	/**
	 * Set the primary trigger.
	 * @param primary the trigger.
	 */
	public final void setPrimary(Trigger primary) {
		Assert.notNull(primary, "'primary' cannot be null");
		this.primary = primary;
	}

	/**
	 * Set the override trigger; set to null to revert to using the
	 * primary trigger.
	 * @param override the override trigger, or null.
	 */
	public void setOverride(Trigger override) {
		this.override = override;
	}

	@Override
	public Date nextExecutionTime(TriggerContext triggerContext) {
		if (this.override != null) {
			return this.override.nextExecutionTime(triggerContext);
		}
		else {
			return this.primary.nextExecutionTime(triggerContext);
		}
	}

}

CompoundTriggerAdvice.java

/*
 * Copyright 2015 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 example;

import org.springframework.integration.core.MessageSource;
import org.springframework.integration.util.CompoundTrigger;
import org.springframework.messaging.Message;
import org.springframework.scheduling.Trigger;
import org.springframework.util.Assert;

/**
 * An {@link AbstractMessageSourceAdvice} that uses a {@link CompoundTrigger} to adjust
 * the poller - when a message is present, the compound trigger's primary trigger is
 * used to determine the next poll. When no message is present, the override trigger is
 * used.
 * <p>
 * The poller advised by this class must be configured to use the same
 * {@link CompoundTrigger} instance and must <b>not</b> use a task executor.
 *
 * @author Gary Russell
 * @since 4.3
 *
 */
public class CompoundTriggerAdvice extends AbstractMessageSourceAdvice {

	private final CompoundTrigger compoundTrigger;

	private final Trigger override;

	public CompoundTriggerAdvice(CompoundTrigger compoundTrigger, Trigger overrideTrigger) {
		Assert.notNull(compoundTrigger, "'compoundTrigger' cannot be null");
		this.compoundTrigger = compoundTrigger;
		this.override = overrideTrigger;
	}

	@Override
	public boolean beforeReceive(MessageSource<?> source) {
		return true;
	}

	@Override
	public Message<?> afterReceive(Message<?> result, MessageSource<?> source) {
		if (result == null) {
			this.compoundTrigger.setOverride(this.override);
		}
		else {
			this.compoundTrigger.setOverride(null);
		}
		return result;
	}

}

xcompound-trigger-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:int="http://www.springframework.org/schema/integration"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd">

	<int:inbound-channel-adapter channel="nullChannel" auto-startup="false">
		<bean class="example.Source" />
		<int:poller trigger="compoundTrigger">
			<int:advice-chain>
				<bean class="example.CompoundTriggerAdvice">
					<constructor-arg ref="compoundTrigger"/>
					<constructor-arg ref="secondary"/>
				</bean>
			</int:advice-chain>
		</int:poller>
	</int:inbound-channel-adapter>

	<bean id="compoundTrigger" class="example.CompoundTrigger">
		<constructor-arg ref="primary" />
	</bean>

	<bean id="primary" class="org.springframework.scheduling.support.CronTrigger">
		<constructor-arg value="*/1 * * * * *" />
	</bean>

	<bean id="secondary" class="org.springframework.scheduling.support.PeriodicTrigger">
		<constructor-arg value="10" />
	</bean>

</beans>