// 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
// 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.cloud.utils.db;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import com.mysql.jdbc.BalanceStrategy;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.ConnectionImpl;
import com.mysql.jdbc.LoadBalancingConnectionProxy;
import com.mysql.jdbc.SQLError;
public class StaticStrategy implements BalanceStrategy {
public StaticStrategy() {
}
@Override
public void destroy() {
// we don't have anything to clean up
}
@Override
public void init(Connection conn, Properties props) throws SQLException {
// we don't have anything to initialize
}
@Override
public ConnectionImpl pickConnection(LoadBalancingConnectionProxy proxy, List<String> configuredHosts, Map<String, ConnectionImpl> liveConnections,
long[] responseTimes, int numRetries) throws SQLException {
int numHosts = configuredHosts.size();
SQLException ex = null;
List<String> whiteList = new ArrayList<String>(numHosts);
whiteList.addAll(configuredHosts);
Map<String, Long> blackList = proxy.getGlobalBlacklist();
whiteList.removeAll(blackList.keySet());
Map<String, Integer> whiteListMap = this.getArrayIndexMap(whiteList);
for (int attempts = 0; attempts < numRetries;) {
if (whiteList.size() == 0) {
throw SQLError.createSQLException("No hosts configured", null);
}
String hostPortSpec = whiteList.get(0); //Always take the first host
ConnectionImpl conn = liveConnections.get(hostPortSpec);
if (conn == null) {
try {
conn = proxy.createConnectionForHost(hostPortSpec);
} catch (SQLException sqlEx) {
ex = sqlEx;
if (proxy.shouldExceptionTriggerFailover(sqlEx)) {
Integer whiteListIndex = whiteListMap.get(hostPortSpec);
// exclude this host from being picked again
if (whiteListIndex != null) {
whiteList.remove(whiteListIndex.intValue());
whiteListMap = this.getArrayIndexMap(whiteList);
}
proxy.addToGlobalBlacklist(hostPortSpec);
if (whiteList.size() == 0) {
attempts++;
try {
Thread.sleep(250);
} catch (InterruptedException e) {
}
// start fresh
whiteListMap = new HashMap<String, Integer>(numHosts);
whiteList.addAll(configuredHosts);
blackList = 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<String, Integer> getArrayIndexMap(List<String> l) {
Map<String, Integer> m = new HashMap<String, Integer>(l.size());
for (int i = 0; i < l.size(); i++) {
m.put(l.get(i), Integer.valueOf(i));
}
return m;
}
}