/*
* Copyright 2012-2017 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.springframework.boot.actuate.cache;
import java.lang.management.ManagementFactory;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.management.AttributeNotFoundException;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.ReflectionException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
/**
* Base {@link CacheStatisticsProvider} implementation that uses JMX to retrieve the cache
* statistics.
*
* @param <C> The cache type
* @author Stephane Nicoll
* @since 1.3.0
*/
public abstract class AbstractJmxCacheStatisticsProvider<C extends Cache>
implements CacheStatisticsProvider<C> {
private static final Logger logger = LoggerFactory
.getLogger(AbstractJmxCacheStatisticsProvider.class);
private MBeanServer mBeanServer;
private final Map<String, ObjectNameWrapper> caches = new ConcurrentHashMap<>();
@Override
public CacheStatistics getCacheStatistics(CacheManager cacheManager, C cache) {
try {
ObjectName objectName = internalGetObjectName(cache);
return (objectName == null ? null : getCacheStatistics(objectName));
}
catch (MalformedObjectNameException ex) {
throw new IllegalStateException(ex);
}
}
/**
* Return the {@link ObjectName} of the MBean that is managing the specified cache or
* {@code null} if none is found.
* @param cache the cache to handle
* @return the object name of the cache statistics MBean
* @throws MalformedObjectNameException if the {@link ObjectName} for that cache is
* invalid
*/
protected abstract ObjectName getObjectName(C cache)
throws MalformedObjectNameException;
/**
* Return the current {@link CacheStatistics} snapshot from the MBean identified by
* the specified {@link ObjectName}.
* @param objectName the object name of the cache statistics MBean
* @return the current cache statistics
*/
protected abstract CacheStatistics getCacheStatistics(ObjectName objectName);
private ObjectName internalGetObjectName(C cache)
throws MalformedObjectNameException {
String cacheName = cache.getName();
ObjectNameWrapper value = this.caches.get(cacheName);
if (value != null) {
return value.objectName;
}
ObjectName objectName = getObjectName(cache);
this.caches.put(cacheName, new ObjectNameWrapper(objectName));
return objectName;
}
protected MBeanServer getMBeanServer() {
if (this.mBeanServer == null) {
this.mBeanServer = ManagementFactory.getPlatformMBeanServer();
}
return this.mBeanServer;
}
protected <T> T getAttribute(ObjectName objectName, String attributeName,
Class<T> type) {
try {
Object attribute = getMBeanServer().getAttribute(objectName, attributeName);
return type.cast(attribute);
}
catch (MBeanException ex) {
throw new IllegalStateException(ex);
}
catch (AttributeNotFoundException ex) {
throw new IllegalStateException("Unexpected: MBean with name '" + objectName
+ "' " + "does not expose attribute with name " + attributeName, ex);
}
catch (ReflectionException ex) {
throw new IllegalStateException(ex);
}
catch (InstanceNotFoundException ex) {
logger.warn("Cache statistics are no longer available", ex);
return null;
}
}
private static class ObjectNameWrapper {
private final ObjectName objectName;
ObjectNameWrapper(ObjectName objectName) {
this.objectName = objectName;
}
}
}