org.springframework.context.SmartLifecycle Maven / Gradle / Ivy
/*
* Copyright 2002-2011 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.context;
/**
* An extension of the {@link Lifecycle} interface for those objects that require to be
* started upon ApplicationContext refresh and/or shutdown in a particular order.
* The {@link #isAutoStartup()} return value indicates whether this object should
* be started at the time of a context refresh. The callback-accepting
* {@link #stop(Runnable)} method is useful for objects that have an asynchronous
* shutdown process. Any implementation of this interface must invoke the
* callback's run() method upon shutdown completion to avoid unnecessary delays
* in the overall ApplicationContext shutdown.
*
* This interface extends {@link Phased}, and the {@link #getPhase()} method's
* return value indicates the phase within which this Lifecycle component should
* be started and stopped. The startup process begins with the lowest
* phase value and ends with the highest phase value (Integer.MIN_VALUE
* is the lowest possible, and Integer.MAX_VALUE is the highest possible). The
* shutdown process will apply the reverse order. Any components with the
* same value will be arbitrarily ordered within the same phase.
*
*
Example: if component B depends on component A having already started, then
* component A should have a lower phase value than component B. During the
* shutdown process, component B would be stopped before component A.
*
*
Any explicit "depends-on" relationship will take precedence over
* the phase order such that the dependent bean always starts after its
* dependency and always stops before its dependency.
*
*
Any Lifecycle components within the context that do not also implement
* SmartLifecycle will be treated as if they have a phase value of 0. That
* way a SmartLifecycle implementation may start before those Lifecycle
* components if it has a negative phase value, or it may start after
* those components if it has a positive phase value.
*
*
Note that, due to the auto-startup support in SmartLifecycle,
* a SmartLifecycle bean instance will get initialized on startup of the
* application context in any case. As a consequence, the bean definition
* lazy-init flag has very limited actual effect on SmartLifecycle beans.
*
* @author Mark Fisher
* @since 3.0
*/
public interface SmartLifecycle extends Lifecycle, Phased {
/**
* Return whether this Lifecycle component should be started automatically
* by the container when the ApplicationContext is refreshed. A value of
* "false" indicates that the component is intended to be started manually.
*/
boolean isAutoStartup();
/**
* Indicates that a Lifecycle component must stop if it is currently running.
*
The provided callback is used by the {@link LifecycleProcessor} to support an
* ordered, and potentially concurrent, shutdown of all components having a
* common shutdown order value. The callback must be executed after
* the SmartLifecycle component does indeed stop.
*
The {@code LifecycleProcessor} will call only this variant of the
* {@code stop} method; i.e. {@link Lifecycle#stop()} will not be called for
* {@link SmartLifecycle} implementations unless explicitly delegated to within
* this method.
*/
void stop(Runnable callback);
}