    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
    015    package org.apache.tapestry5.annotations;
    016
    017    import static java.lang.annotation.RetentionPolicy.RUNTIME;
    018    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.COMPONENT;
    019    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.MIXIN;
    020    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.PAGE;
    021
    022    import java.lang.annotation.Documented;
    023    import java.lang.annotation.ElementType;
    024    import java.lang.annotation.Retention;
    025    import java.lang.annotation.Target;
    026
    027    import org.apache.tapestry5.internal.transform.HeartbeatDeferredWorker;
    028    import org.apache.tapestry5.ioc.annotations.UseWith;
    029    import 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 })
    050    public @interface HeartbeatDeferred
    051    {
    052
    053    }