[766] | 1 | /* |
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| 2 | Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. |
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| 3 | |
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| 4 | The MySQL Connector/J is licensed under the terms of the GPLv2 |
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| 5 | <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors. |
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| 6 | There are special exceptions to the terms and conditions of the GPLv2 as it is applied to |
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| 7 | this software, see the FLOSS License Exception |
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| 8 | <http://www.mysql.com/about/legal/licensing/foss-exception.html>. |
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| 9 | |
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| 10 | This program is free software; you can redistribute it and/or modify it under the terms |
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| 11 | of the GNU General Public License as published by the Free Software Foundation; version 2 |
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| 12 | of the License. |
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| 13 | |
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| 14 | This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; |
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| 15 | without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
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| 16 | See the GNU General Public License for more details. |
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| 17 | |
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| 18 | You should have received a copy of the GNU General Public License along with this |
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| 19 | program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth |
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| 20 | Floor, Boston, MA 02110-1301 USA |
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| 21 | |
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| 22 | */ |
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| 23 | package com.mysql.jdbc; |
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| 24 | |
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| 25 | import java.sql.SQLException; |
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| 26 | import java.util.List; |
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| 27 | import java.util.Map; |
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| 28 | import java.util.Properties; |
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| 29 | |
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| 30 | public class BestResponseTimeBalanceStrategy implements BalanceStrategy { |
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| 31 | |
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| 32 | /** |
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| 33 | * @param loadBalancingConnectionProxy |
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| 34 | */ |
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| 35 | public BestResponseTimeBalanceStrategy() { |
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| 36 | } |
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| 37 | |
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| 38 | public void destroy() { |
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| 39 | // we don't have anything to clean up |
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| 40 | } |
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| 41 | |
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| 42 | public void init(Connection conn, Properties props) throws SQLException { |
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| 43 | // we don't have anything to initialize |
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| 44 | } |
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| 45 | |
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| 46 | public ConnectionImpl pickConnection(LoadBalancingConnectionProxy proxy, |
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| 47 | List<String> configuredHosts, Map<String, ConnectionImpl> liveConnections, long[] responseTimes, |
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| 48 | int numRetries) throws SQLException { |
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| 49 | |
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| 50 | Map<String, Long> blackList = proxy.getGlobalBlacklist(); |
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| 51 | |
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| 52 | SQLException ex = null; |
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| 53 | |
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| 54 | for (int attempts = 0; attempts < numRetries; ) { |
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| 55 | long minResponseTime = Long.MAX_VALUE; |
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| 56 | |
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| 57 | int bestHostIndex = 0; |
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| 58 | |
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| 59 | // safety |
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| 60 | if (blackList.size() == configuredHosts.size()) { |
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| 61 | blackList = proxy.getGlobalBlacklist(); |
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| 62 | } |
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| 63 | |
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| 64 | for (int i = 0; i < responseTimes.length; i++) { |
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| 65 | long candidateResponseTime = responseTimes[i]; |
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| 66 | |
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| 67 | if (candidateResponseTime < minResponseTime |
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| 68 | && !blackList.containsKey(configuredHosts.get(i))) { |
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| 69 | if (candidateResponseTime == 0) { |
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| 70 | bestHostIndex = i; |
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| 71 | |
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| 72 | break; |
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| 73 | } |
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| 74 | |
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| 75 | bestHostIndex = i; |
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| 76 | minResponseTime = candidateResponseTime; |
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| 77 | } |
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| 78 | } |
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| 79 | |
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| 80 | String bestHost = configuredHosts.get(bestHostIndex); |
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| 81 | |
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| 82 | ConnectionImpl conn = liveConnections.get(bestHost); |
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| 83 | |
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| 84 | if (conn == null) { |
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| 85 | try { |
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| 86 | conn = proxy.createConnectionForHost(bestHost); |
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| 87 | } catch (SQLException sqlEx) { |
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| 88 | ex = sqlEx; |
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| 89 | |
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| 90 | if (proxy.shouldExceptionTriggerFailover(sqlEx)) { |
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| 91 | proxy.addToGlobalBlacklist(bestHost); |
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| 92 | blackList.put(bestHost, null); |
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| 93 | |
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| 94 | |
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| 95 | if (blackList.size() == configuredHosts.size()) { |
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| 96 | attempts++; |
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| 97 | try { |
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| 98 | Thread.sleep(250); |
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| 99 | } catch (InterruptedException e) { |
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| 100 | } |
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| 101 | blackList = proxy.getGlobalBlacklist(); // try again after a little bit |
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| 102 | } |
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| 103 | |
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| 104 | continue; |
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| 105 | } |
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| 106 | |
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| 107 | throw sqlEx; |
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| 108 | } |
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| 109 | } |
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| 110 | |
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| 111 | return conn; |
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| 112 | } |
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| 113 | |
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| 114 | if (ex != null) { |
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| 115 | throw ex; |
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| 116 | } |
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| 117 | |
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| 118 | return null; // we won't get here, compiler can't tell |
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| 119 | } |
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| 120 | } |
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