001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.model.loadbalancer; 018 019import java.util.ArrayList; 020import java.util.List; 021 022import javax.xml.bind.annotation.XmlAccessType; 023import javax.xml.bind.annotation.XmlAccessorType; 024import javax.xml.bind.annotation.XmlAttribute; 025import javax.xml.bind.annotation.XmlElement; 026import javax.xml.bind.annotation.XmlRootElement; 027import javax.xml.bind.annotation.XmlTransient; 028 029import org.apache.camel.model.LoadBalancerDefinition; 030import org.apache.camel.processor.loadbalancer.CircuitBreakerLoadBalancer; 031import org.apache.camel.processor.loadbalancer.LoadBalancer; 032import org.apache.camel.spi.Metadata; 033import org.apache.camel.spi.RouteContext; 034import org.apache.camel.util.ObjectHelper; 035 036/** 037 * Circuit break load balancer 038 * <p/> 039 * The Circuit Breaker load balancer is a stateful pattern that monitors all calls for certain exceptions. 040 * Initially the Circuit Breaker is in closed state and passes all messages. 041 * If there are failures and the threshold is reached, it moves to open state and rejects all calls until halfOpenAfter 042 * timeout is reached. After this timeout is reached, if there is a new call, it will pass and if the result is 043 * success the Circuit Breaker will move to closed state, or to open state if there was an error. 044 * 045 * @deprecated use Hystrix EIP instead which is the popular Netflix implementation of circuit breaker 046 */ 047@Metadata(label = "eip,routing,loadbalance,circuitbreaker") 048@XmlRootElement(name = "circuitBreaker") 049@XmlAccessorType(XmlAccessType.FIELD) 050@Deprecated 051public class CircuitBreakerLoadBalancerDefinition extends LoadBalancerDefinition { 052 @XmlTransient 053 private List<Class<?>> exceptionTypes = new ArrayList<>(); 054 @XmlElement(name = "exception") 055 private List<String> exceptions = new ArrayList<>(); 056 @XmlAttribute 057 private Long halfOpenAfter; 058 @XmlAttribute 059 private Integer threshold; 060 061 public CircuitBreakerLoadBalancerDefinition() { 062 } 063 064 @Override 065 protected int getMaximumNumberOfOutputs() { 066 // we can only support 1 output 067 return 1; 068 } 069 070 @Override 071 protected LoadBalancer createLoadBalancer(RouteContext routeContext) { 072 CircuitBreakerLoadBalancer answer; 073 074 List<Class<?>> classes = new ArrayList<>(); 075 if (!exceptionTypes.isEmpty()) { 076 classes.addAll(exceptionTypes); 077 } else if (!exceptions.isEmpty()) { 078 for (String name : exceptions) { 079 Class<?> type = routeContext.getCamelContext().getClassResolver().resolveClass(name); 080 if (type == null) { 081 throw new IllegalArgumentException("Cannot find class: " + name + " in the classpath"); 082 } 083 if (!ObjectHelper.isAssignableFrom(Throwable.class, type)) { 084 throw new IllegalArgumentException("Class is not an instance of Throwable: " + type); 085 } 086 classes.add(type); 087 } 088 } 089 if (classes.isEmpty()) { 090 answer = new CircuitBreakerLoadBalancer(); 091 } else { 092 answer = new CircuitBreakerLoadBalancer(classes); 093 } 094 095 if (getHalfOpenAfter() != null) { 096 answer.setHalfOpenAfter(getHalfOpenAfter()); 097 } 098 if (getThreshold() != null) { 099 answer.setThreshold(getThreshold()); 100 } 101 return answer; 102 } 103 104 public Long getHalfOpenAfter() { 105 return halfOpenAfter; 106 } 107 108 /** 109 * The timeout in millis to use as threshold to move state from closed to half-open or open state 110 */ 111 public void setHalfOpenAfter(Long halfOpenAfter) { 112 this.halfOpenAfter = halfOpenAfter; 113 } 114 115 public Integer getThreshold() { 116 return threshold; 117 } 118 119 /** 120 * Number of previous failed messages to use as threshold to move state from closed to half-open or open state 121 */ 122 public void setThreshold(Integer threshold) { 123 this.threshold = threshold; 124 } 125 126 public List<String> getExceptions() { 127 return exceptions; 128 } 129 130 /** 131 * A list of class names for specific exceptions to monitor. 132 * If no exceptions is configured then all exceptions is monitored 133 */ 134 public void setExceptions(List<String> exceptions) { 135 this.exceptions = exceptions; 136 } 137 138 public List<Class<?>> getExceptionTypes() { 139 return exceptionTypes; 140 } 141 142 /** 143 * A list of specific exceptions to monitor. 144 * If no exceptions is configured then all exceptions is monitored 145 */ 146 public void setExceptionTypes(List<Class<?>> exceptionTypes) { 147 this.exceptionTypes = exceptionTypes; 148 } 149 150 @Override 151 public String toString() { 152 return "CircuitBreakerLoadBalancer"; 153 } 154}