org.apache.distributedlog.client.routing.ServerSetWatcher Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.distributedlog.client.routing;
import com.google.common.collect.ImmutableSet;
import org.apache.distributedlog.service.DLSocketAddress;
/**
* Watch on server set changes.
*/
public interface ServerSetWatcher {
/**
* Exception thrown when failed to monitor serverset.
*/
class MonitorException extends Exception {
private static final long serialVersionUID = 392751505154339548L;
public MonitorException(String msg) {
super(msg);
}
public MonitorException(String msg, Throwable cause) {
super(msg, cause);
}
}
/**
* An interface to an object that is interested in receiving notification whenever the host set changes.
*/
interface ServerSetMonitor {
/**
* Called when either the available set of services changes.
*
* It happens either when a service dies or a new INSTANCE comes on-line or
* when an existing service advertises a status or health change.
*
* @param hostSet the current set of available ServiceInstances
*/
void onChange(ImmutableSet hostSet);
}
/**
* Registers a monitor to receive change notices for this server set as long as this jvm process is alive.
*
* Blocks until the initial server set can be gathered and delivered to the monitor.
* The monitor will be notified if the membership set or parameters of existing members have
* changed.
*
* @param monitor the server set monitor to call back when the host set changes
* @throws MonitorException if there is a problem monitoring the host set
*/
void watch(final ServerSetMonitor monitor) throws MonitorException;
}