org.zkybase.kite.circuitbreaker.interceptor.AnnotationCircuitBreakerSource.java Source code

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Here is the source code for org.zkybase.kite.circuitbreaker.interceptor.AnnotationCircuitBreakerSource.java

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/*
 * Copyright (c) 2010 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.zkybase.kite.circuitbreaker.interceptor;

import java.io.Serializable;
import java.lang.reflect.Method;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.zkybase.kite.annotation.GuardedByCircuitBreaker;
import org.zkybase.kite.circuitbreaker.CircuitBreakerTemplate;

// TODO Consider implementing breaker cache. See Spring's
// AbstractFallbackTransactionAttributeSource

/**
 * @version $Id: AnnotationCircuitBreakerSource.java 75 2010-03-29 07:34:59Z willie.wheeler $
 * @author Willie Wheeler
 */
@SuppressWarnings("serial")
public class AnnotationCircuitBreakerSource implements CircuitBreakerSource, BeanFactoryAware, Serializable {

    private static final Class<GuardedByCircuitBreaker> ANN_CLASS = GuardedByCircuitBreaker.class;
    //   private static Logger log = LoggerFactory.getLogger(AnnotationCircuitBreakerSource.class);

    private BeanFactory beanFactory;

    /**
     * @param beanFactory
     */
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }

    public CircuitBreakerTemplate getBreaker(Method method, Class<?> targetClass) {
        Assert.notNull(method, "method can't be null");

        // Method may be on an interface, but we need annotations from the
        // target class. If target class is null, method will be unchanged.
        Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);

        // If we are dealing with a method with generic parameters, find the
        // original, bridged method.
        specificMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);

        CircuitBreakerTemplate breaker = parseAnnotation(specificMethod);
        return (breaker != null ? breaker : parseAnnotation(method));
    }

    // Based on SpringTransactionAnnotationParser. Don't worry about meta-
    // annotations here, because GuardedByCircuitBreaker is allowed only on
    // methods.
    private CircuitBreakerTemplate parseAnnotation(Method method) {
        GuardedByCircuitBreaker ann = method.getAnnotation(ANN_CLASS);
        return (ann == null ? null : beanFactory.getBean(ann.value(), CircuitBreakerTemplate.class));
    }
}