/*
* Copyright 1999-2011 Alibaba Group.
*
* 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 com.alibaba.dubbo.monitor.support;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.monitor.Monitor;
import com.alibaba.dubbo.monitor.MonitorFactory;
/**
* AbstractMonitorFactroy. (SPI, Singleton, ThreadSafe)
*
* @author william.liangf
*/
public abstract class AbstractMonitorFactroy implements MonitorFactory {
// 注册中心获取过程锁
private static final ReentrantLock LOCK = new ReentrantLock();
// 注册中心集合 Map<RegistryAddress, Registry>
private static final Map<String, Monitor> MONITORS = new ConcurrentHashMap<String, Monitor>();
public static Collection<Monitor> getMonitors() {
return Collections.unmodifiableCollection(MONITORS.values());
}
public Monitor getMonitor(URL url) {
LOCK.lock();
try {
String uri = url.toIdentityString();
Monitor monitor = MONITORS.get(uri);
if (monitor != null) {
return monitor;
}
monitor = createMonitor(url);
if (monitor == null) {
throw new IllegalStateException("Can not create monitor " + url);
}
MONITORS.put(uri, monitor);
return monitor;
} finally {
// 释放锁
LOCK.unlock();
}
}
protected abstract Monitor createMonitor(URL url);
}