    001// Copyright 2010 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007// http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.annotations;
    016
    017import static java.lang.annotation.RetentionPolicy.RUNTIME;
    018import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.COMPONENT;
    019import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.MIXIN;
    020import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.PAGE;
    021
    022import java.lang.annotation.Documented;
    023import java.lang.annotation.ElementType;
    024import java.lang.annotation.Retention;
    025import java.lang.annotation.Target;
    026
    027import org.apache.tapestry5.internal.transform.HeartbeatDeferredWorker;
    028import org.apache.tapestry5.ioc.annotations.UseWith;
    029import org.apache.tapestry5.services.Heartbeat;
    030
    031/**
    032 * Marks a component method as deferred until the end of the {@link Heartbeat}. This
    033 * is only allowed on void methods that do not throw exceptions. The invocation is captured
    034 * and will execute at the end of the current Heartbeat.
    035 * <p>
    036 * This annotation should be used with care, since deferring the invocation can change its semantics. For example, the
    037 * value stored in instance variables may change between the time the method is invoked and the time it eventually
    038 * executes. Likewise, runtime exceptions thrown by the method can not be caught by the invoking method.
    039 * <p>
    040 * Annotated methods must return void, and not declare any checked exceptions.
    041 *
    042 * @since 5.2.0
    043 * @see HeartbeatDeferredWorker
    044 */
    045@Target(ElementType.METHOD)
    046@Retention(RUNTIME)
    047@Documented
    048@UseWith(
    049{ COMPONENT, MIXIN, PAGE })
    050public @interface HeartbeatDeferred
    051{
    052
    053}