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/**
* Mule Development Kit
* Copyright 2010-2011 (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com
*
* 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.
*/
/**
* This file was automatically generated by the Mule Development Kit
*/
package com.acmesoft;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.mule.api.MuleContext;
import org.mule.api.annotations.Module;
import org.mule.api.annotations.Configurable;
import org.mule.api.annotations.Processor;
import org.mule.api.annotations.param.Payload;
import org.mule.api.config.MuleProperties;
import org.mule.api.context.MuleContextAware;
import org.mule.api.registry.RegistrationException;
import org.mule.api.store.ObjectStore;
import org.mule.api.store.ObjectStoreManager;
import org.mule.message.ExceptionMessage;
import javax.inject.Inject;
import java.util.Date;
import java.util.concurrent.Semaphore;
/**
* An implementation of Michael Nygard's CircuitBreaker pattern.
*
* @author MuleSoft, Inc.
*/
@Module(name = "circuitbreaker", schemaVersion = "1.0-SNAPSHOT")
public class CircuitBreakerModule implements MuleContextAware {
protected transient Log logger = LogFactory.getLog(getClass());
/**
* The amount of failures until the circuit breaker is tripped.
*/
@Configurable
private int tripThreshold;
/**
* How long to wait until the breaker is automatically reset.
*/
@Configurable
private long tripTimeout;
/**
* The name of this breaker.
*/
@Configurable
private String breakerName;
private Date breakerTrippedOn;
private Semaphore objectStoreMutex = new Semaphore(1);
MuleContext muleContext;
@Inject
private ObjectStoreManager objectStoreManager;
public void setTripThreshold(int tripThreshold) {
this.tripThreshold = tripThreshold;
}
public void setTripTimeout(long tripTimeout) {
this.tripTimeout = tripTimeout;
}
public void setBreakerName(String breakerName) {
this.breakerName = breakerName;
}
public void setMuleContext(MuleContext muleContext) {
this.muleContext = muleContext;
}
/**
* Custom processor
* <p/>
* {@sample.xml ../../../doc/CircuitBreaker-connector.xml.sample circuitbreaker:filter}
*
* @param payload The message payload
* @return Some string
*/
@Processor
public Object filter(@Payload Object payload) {
if (getFailureCount() < tripThreshold) {
return payload;
} else if (breakerTrippedOn != null && System.currentTimeMillis() - breakerTrippedOn.getTime() > tripTimeout) {
breakerTrippedOn = null;
resetFailureCount();
return payload;
} else {
throw new CircuitOpenException();
}
}
/**
* Custom processor
* <p/>
* {@sample.xml ../../../doc/CircuitBreaker-connector.xml.sample circuitbreaker:trip}
*
* @param exceptionMessage The exception.
* @param tripOnException The exception type we should trip on.
* @return Some string
*/
@Processor
public Object trip(String tripOnException, @Payload ExceptionMessage exceptionMessage) {
if (exceptionMessage.getException().getCause().getClass().getCanonicalName().equals(tripOnException)) {
incrementFailureCount();
if (getFailureCount() == tripThreshold) {
breakerTrippedOn = new Date();
}
}
return exceptionMessage;
}
Integer getFailureCount() {
try {
objectStoreMutex.acquire();
} catch (InterruptedException e) {
logger.error("Could not acquire mutex", e);
}
ObjectStore objectStore = objectStoreManager.getObjectStore(MuleProperties.OBJECT_STORE_DEFAULT_PERSISTENT_NAME);
String key = String.format("%s.failureCount", breakerName);
Integer failureCount = 0;
try {
if (objectStore.contains(key)) {
failureCount = (Integer) objectStore.retrieve(key);
}
} catch (Exception e) {
logger.error("Could not retrieve key from object-store: " + key, e);
}
objectStoreMutex.release();
return failureCount;
}
void incrementFailureCount() {
try {
objectStoreMutex.acquire();
} catch (InterruptedException e) {
logger.error("Could not acquire mutex", e);
}
ObjectStore objectStore = objectStoreManager.getObjectStore(MuleProperties.OBJECT_STORE_DEFAULT_PERSISTENT_NAME);
String key = String.format("%s.failureCount", breakerName);
Integer failureCount = 0;
try {
if (objectStore.contains(key)) {
failureCount = (Integer) objectStore.retrieve(key);
objectStore.remove(key);
}
objectStore.store(key, failureCount + 1);
} catch (Exception e) {
logger.error("Could not retrieve key from object-store: " + key, e);
}
objectStoreMutex.release();
}
void resetFailureCount() {
try {
objectStoreMutex.acquire();
} catch (InterruptedException e) {
logger.error("Could not acquire mutex", e);
}
ObjectStore objectStore = objectStoreManager.getObjectStore(MuleProperties.OBJECT_STORE_DEFAULT_PERSISTENT_NAME);
String key = String.format("%s.failureCount", breakerName);
Integer failureCount = 0;
try {
if (objectStore.contains(key)) {
failureCount = (Integer) objectStore.retrieve(key);
objectStore.remove(key);
}
objectStore.store(key, 0);
} catch (Exception e) {
logger.error("Could not retrieve key from object-store: " + key, e);
}
objectStoreMutex.release();
}
}
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