# BreakCircuitConcern.java

    /*
     * Copyright 2009-2010 Rickard Öberg AB
     *
     * 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.qi4j.library.circuitbreaker.service;

    import java.lang.reflect.Method;
    import org.qi4j.api.common.AppliesTo;
    import org.qi4j.api.concern.GenericConcern;
    import org.qi4j.api.injection.scope.This;
    import org.qi4j.library.circuitbreaker.CircuitBreaker;

    /**
     * This concern will update the circuit breaker on method invocation success
     * and thrown exceptions.
     */
    @AppliesTo( BreaksCircuitOnThrowable.class )
    public class BreakCircuitConcern
            extends GenericConcern
    {

        @This
        ServiceCircuitBreaker serviceCircuitBreaker;

        @Override
        public Object invoke( Object proxy, Method method, Object[] args )
                throws Throwable
        {
            CircuitBreaker circuitBreaker = serviceCircuitBreaker.circuitBreaker();
            try
            {
                if( !circuitBreaker.isOn() )
                {
                    throw circuitBreaker.lastThrowable();
                }

                Object result = next.invoke( proxy, method, args );
                circuitBreaker.success();
                return result;

            } catch( Throwable throwable )
            {
                circuitBreaker.throwable( throwable );
                throw throwable;
            }
        }

    }