content: /*
   * 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.interceptors;
  
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Properties;
  import java.util.function.Supplier;
  
  import com.mysql.cj.MysqlConnection;
  import com.mysql.cj.Query;
  import com.mysql.cj.exceptions.ExceptionFactory;
  import com.mysql.cj.interceptors.QueryInterceptor;
  import com.mysql.cj.jdbc.JdbcConnection;
  import com.mysql.cj.log.Log;
  import com.mysql.cj.protocol.Resultset;
  import com.mysql.cj.protocol.ServerSession;
  import com.mysql.cj.util.Util;
  
  public class ServerStatusDiffInterceptor implements QueryInterceptor {
  
      private Map<String, String> preExecuteValues = new HashMap<>();
  
      private Map<String, String> postExecuteValues = new HashMap<>();
  
      private JdbcConnection connection;
  
      private Log log;
  
      @Override
      public QueryInterceptor init(MysqlConnection conn, Properties props, Log l) {
          this.connection = (JdbcConnection) conn;
          this.log = l;
          return this;
      }
  
      @Override
      public <T extends Resultset> T postProcess(Supplier<String> sql, Query interceptedQuery, T originalResultSet, ServerSession serverSession) {
  
          populateMapWithSessionStatusValues(this.postExecuteValues);
  
          this.log.logInfo("Server status change for query:\n" + Util.calculateDifferences(this.preExecuteValues, this.postExecuteValues));
  
          return null; // we don't actually modify a result set
  
      }
  
      private void populateMapWithSessionStatusValues(Map<String, String> toPopulate) {
          try {
              try (Statement stmt = this.connection.createStatement()) {
                  toPopulate.clear();
  
                  try (ResultSet rs = stmt.executeQuery("SHOW SESSION STATUS")) {
                      while (rs.next()) {
                          toPopulate.put(rs.getString(1), rs.getString(2));
                      }
                  }
              }
          } catch (SQLException ex) {
              throw ExceptionFactory.createException(ex.getMessage(), ex);
          }
      }
  
      @Override
      public <T extends Resultset> T preProcess(Supplier<String> sql, Query interceptedQuery) {
  
          populateMapWithSessionStatusValues(this.preExecuteValues);
  
          return null; // we don't actually modify a result set
      }
  
      @Override
      public boolean executeTopLevelOnly() {
          return true;
      }
  
      @Override
      public void destroy() {
          this.connection = null;
          this.log = null;
      }
  }
  