com.mysql.cj.jdbc.ha.RandomBalanceStrategy 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
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
* for more details.
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package com.mysql.cj.jdbc.ha;
import java.lang.reflect.InvocationHandler;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.mysql.cj.Messages;
import com.mysql.cj.jdbc.ConnectionImpl;
import com.mysql.cj.jdbc.JdbcConnection;
import com.mysql.cj.jdbc.exceptions.SQLError;
public class RandomBalanceStrategy implements BalanceStrategy {
public RandomBalanceStrategy() {
}
@Override
public ConnectionImpl pickConnection(InvocationHandler proxy, List configuredHosts, Map liveConnections,
long[] responseTimes, int numRetries) throws SQLException {
int numHosts = configuredHosts.size();
SQLException ex = null;
List whiteList = new ArrayList<>(numHosts);
whiteList.addAll(configuredHosts);
Map blackList = ((LoadBalancedConnectionProxy) proxy).getGlobalBlacklist();
whiteList.removeAll(blackList.keySet());
Map whiteListMap = this.getArrayIndexMap(whiteList);
for (int attempts = 0; attempts < numRetries;) {
int random = (int) Math.floor((Math.random() * whiteList.size()));
if (whiteList.size() == 0) {
throw SQLError.createSQLException(Messages.getString("RandomBalanceStrategy.0"), null);
}
String hostPortSpec = whiteList.get(random);
ConnectionImpl conn = (ConnectionImpl) liveConnections.get(hostPortSpec);
if (conn == null) {
try {
conn = ((LoadBalancedConnectionProxy) proxy).createConnectionForHost(hostPortSpec);
} catch (SQLException sqlEx) {
ex = sqlEx;
if (((LoadBalancedConnectionProxy) proxy).shouldExceptionTriggerConnectionSwitch(sqlEx)) {
Integer whiteListIndex = whiteListMap.get(hostPortSpec);
// exclude this host from being picked again
if (whiteListIndex != null) {
whiteList.remove(whiteListIndex.intValue());
whiteListMap = this.getArrayIndexMap(whiteList);
}
((LoadBalancedConnectionProxy) proxy).addToGlobalBlacklist(hostPortSpec);
if (whiteList.size() == 0) {
attempts++;
try {
Thread.sleep(250);
} catch (InterruptedException e) {
}
// start fresh
whiteListMap = new HashMap<>(numHosts);
whiteList.addAll(configuredHosts);
blackList = ((LoadBalancedConnectionProxy) proxy).getGlobalBlacklist();
whiteList.removeAll(blackList.keySet());
whiteListMap = this.getArrayIndexMap(whiteList);
}
continue;
}
throw sqlEx;
}
}
return conn;
}
if (ex != null) {
throw ex;
}
return null; // we won't get here, compiler can't tell
}
private Map getArrayIndexMap(List l) {
Map m = new HashMap<>(l.size());
for (int i = 0; i < l.size(); i++) {
m.put(l.get(i), Integer.valueOf(i));
}
return m;
}
}