geode-core/src/main/java/org/apache/geode/cache/client/internal/ConnectionSource.java

/*
 * 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.geode.cache.client.internal;

import java.net.InetSocketAddress;
import java.util.List;
import java.util.Set;

import org.apache.geode.distributed.internal.ServerLocation;
import org.apache.geode.internal.cache.tier.sockets.ClientProxyMembershipID;


/**
 * A source for discovering servers and finding the least loaded server to connect to.
 *
 * @since GemFire 5.7
 *
 */
public interface ConnectionSource {

  ServerLocation findServer(Set<ServerLocation> excludedServers);

  /**
   * Asks if we should replace a connection to <code>currentServer</code> with one to the returned
   * server.
   *
   * @param currentServer the server we currently have a connection to.
   * @param excludedServers the replacement server can not be one in this set
   * @return the server we should connect to; <code>currentServer</code> if a replacement is not
   *         needed; <code>null</code> if no server found
   */
  ServerLocation findReplacementServer(ServerLocation currentServer,
      Set<ServerLocation> excludedServers);

  /**
   * Find the servers to host the queue
   *
   * @param excludedServers the servers to exclude from the search
   * @param numServers the number of servers to find, or -1 if we should just find all of them
   * @param proxyId the proxy id for this client
   * @param findDurableQueue if true, the source should make an effort to find the durable queues
   *        for this client
   * @return a list of locations to connect to
   */
  List<ServerLocation> findServersForQueue(Set<ServerLocation> excludedServers,
      int numServers, ClientProxyMembershipID proxyId, boolean findDurableQueue);

  void start(InternalPool poolImpl);

  void stop();

  /**
   * Check to see if the load on the servers is balanced, according to this connection source.
   *
   * @return true if the servers have balanced load.
   */
  boolean isBalanced();

  /**
   * get the list of all the servers
   *
   * @return a list of all servers
   */
  List<ServerLocation> getAllServers();

  /**
   * get the list of online locators
   *
   * @return a list of online locators
   */
  List<InetSocketAddress> getOnlineLocators();
}