com.mysql.cj.jdbc.ha.BalanceStrategy Maven / Gradle / Ivy
/*
* Copyright (c) 2007, 2020, Oracle and/or its affiliates.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License, version 2.0, as published by the
* Free Software Foundation.
*
* This program is also distributed with certain software (including but not
* limited to OpenSSL) that is licensed under separate terms, as designated in a
* particular file or component or in included license documentation. The
* authors of MySQL hereby grant you an additional permission to link the
* program and your derivative works with the separately licensed software that
* they have included with MySQL.
*
* Without limiting anything contained in the foregoing, this file, which is
* part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
* version 1.0, a copy of which can be found at
* http://oss.oracle.com/licenses/universal-foss-exception.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
* for more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.mysql.cj.jdbc.ha;
import java.lang.reflect.InvocationHandler;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;
import com.mysql.cj.jdbc.JdbcConnection;
/**
* Implement this interface to provide a new load balancing strategy for URLs of the form "jdbc:mysql:loadbalance://..", and provide the implementation class
* name as the configuration parameter "loadBalanceStrategy".
*
* The driver will not pass in a Connection instance when calling init(), but it will pass in the Properties, otherwise it acts like a normal Extension.
*
* One instance of a strategy *per* JDBC connection instance will be created. If you need singleton-like behavior, you're on your own to provide it.
*/
public interface BalanceStrategy {
/**
* Called by the driver to pick a new connection to route requests over.
* See LoadBalancedConnectionProxy.createConnectionForHost(String)
*
* @param proxy
* the InvocationHandler that deals with actual method calls to
* the JDBC connection, and serves as a factory for new
* connections for this strategy via the
* createConnectionForHost() method.
*
* This proxy takes care of maintaining the response time list, map of
* host/ports to live connections, and taking connections out of the live
* connections map if they receive a network-related error while they are in
* use by the application.
* @param configuredHosts
* the list of hosts/ports (in "host:port" form) as passed in by
* the user.
* @param liveConnections
* a map of host/ports to "live" connections to them.
* @param responseTimes
* the list of response times for a transaction
* for each host in the configured hosts list.
* @param numRetries
* the number of times the driver expects this strategy to re-try
* connection attempts if creating a new connection fails.
* @return the physical JDBC connection for the application to use, based
* upon the strategy employed.
* @throws SQLException
* if a new connection can not be found or created by this
* strategy.
*/
abstract JdbcConnection pickConnection(InvocationHandler proxy, List configuredHosts, Map liveConnections,
long[] responseTimes, int numRetries) throws SQLException;
}