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