/* Copyright 2012-2013 SpringSource.
 *
 * 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 grails.plugin.cache;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.codehaus.groovy.transform.GroovyASTTransformationClass;

/**
 * Indicates that a method (or all the methods on a class) can be cached.
 *
 * <p>The method arguments and signature are used for computing the key while the
 * returned instance is used as the cache value.
 *
 * @author Jeff Brown
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
@GroovyASTTransformationClass("grails.plugin.cache.compiler.CacheTransformation")
public @interface Cacheable {

    /**
     * Name of the caches in which the update takes place.
     * <p>May be used to determine the target cache (or caches), matching the
     * qualifier value (or the bean name(s)) of (a) specific bean definition.
     */
    String[] value();

    /**
     * Spring Expression Language (SpEL) attribute for computing the key dynamically.
     * <p>Default is "", meaning all method parameters are considered as a key.
     */
    String key() default "";

    /**
     * Spring Expression Language (SpEL) attribute used for conditioning the method caching.
     * <p>Default is "", meaning the method is always cached.
     */
    String condition() default "";
}