/*
 *
 * MariaDB Client for Java
 *
 * Copyright (c) 2012-2014 Monty Program Ab.
 * Copyright (c) 2015-2020 MariaDB Corporation Ab.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with this library; if not, write to Monty Program Ab info@montyprogram.com.
 *
 * This particular MariaDB Client for Java file is work
 * derived from a Drizzle-JDBC. Drizzle-JDBC file which is covered by subject to
 * the following copyright and notice provisions:
 *
 * Copyright (c) 2009-2011, Marcus Eriksson
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or
 * other materials provided with the distribution.
 *
 * Neither the name of the driver nor the names of its contributors may not be
 * used to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS  AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 */

package org.mariadb.jdbc.internal.protocol;

import static org.mariadb.jdbc.internal.com.Packet.*;
import static org.mariadb.jdbc.internal.util.SqlStates.*;

import java.io.*;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.sql.*;
import java.util.*;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.locks.ReentrantLock;
import java.util.regex.Pattern;
import javax.sql.rowset.serial.SerialException;
import org.mariadb.jdbc.*;
import org.mariadb.jdbc.internal.ColumnType;
import org.mariadb.jdbc.internal.MariaDbServerCapabilities;
import org.mariadb.jdbc.internal.com.read.Buffer;
import org.mariadb.jdbc.internal.com.read.ErrorPacket;
import org.mariadb.jdbc.internal.com.read.dao.Results;
import org.mariadb.jdbc.internal.com.read.resultset.ColumnDefinition;
import org.mariadb.jdbc.internal.com.read.resultset.SelectResultSet;
import org.mariadb.jdbc.internal.com.read.resultset.UpdatableResultSet;
import org.mariadb.jdbc.internal.com.send.ComQuery;
import org.mariadb.jdbc.internal.com.send.ComStmtExecute;
import org.mariadb.jdbc.internal.com.send.ComStmtPrepare;
import org.mariadb.jdbc.internal.com.send.SendChangeDbPacket;
import org.mariadb.jdbc.internal.com.send.parameters.ParameterHolder;
import org.mariadb.jdbc.internal.io.LruTraceCache;
import org.mariadb.jdbc.internal.io.output.PacketOutputStream;
import org.mariadb.jdbc.internal.logging.Logger;
import org.mariadb.jdbc.internal.logging.LoggerFactory;
import org.mariadb.jdbc.internal.util.BulkStatus;
import org.mariadb.jdbc.internal.util.LogQueryTool;
import org.mariadb.jdbc.internal.util.SqlStates;
import org.mariadb.jdbc.internal.util.Utils;
import org.mariadb.jdbc.internal.util.constant.ServerStatus;
import org.mariadb.jdbc.internal.util.constant.StateChange;
import org.mariadb.jdbc.internal.util.dao.ClientPrepareResult;
import org.mariadb.jdbc.internal.util.dao.PrepareResult;
import org.mariadb.jdbc.internal.util.dao.ServerPrepareResult;
import org.mariadb.jdbc.internal.util.dao.SqlSocketTimeoutException;
import org.mariadb.jdbc.internal.util.exceptions.ExceptionFactory;
import org.mariadb.jdbc.internal.util.exceptions.MariaDbSqlException;
import org.mariadb.jdbc.internal.util.exceptions.MaxAllowedPacketException;
import org.mariadb.jdbc.internal.util.pool.GlobalStateInfo;
import org.mariadb.jdbc.internal.util.scheduler.SchedulerServiceProviderHolder;

public class AbstractQueryProtocol extends AbstractConnectProtocol implements Protocol {

  private static final Logger logger = LoggerFactory.getLogger(AbstractQueryProtocol.class);
  private static final Set<Integer> LOCK_DEADLOCK_ERROR_CODES =
      new HashSet<>(Arrays.asList(1205, 1213, 1614));
  private static final Pattern LOAD_LOCAL_INFILE =
      Pattern.compile("^(load\\s*(data|xml)\\s*local\\s*infile)", Pattern.CASE_INSENSITIVE);
  private ThreadPoolExecutor readScheduler = null;
  private int transactionIsolationLevel = 0;
  private InputStream localInfileInputStream;
  private long maxRows; /* max rows returned by a statement */
  private volatile int statementIdToRelease = -1;
  private FutureTask activeFutureTask = null;
  private boolean interrupted;

  /**
   * Get a protocol instance.
   *
   * @param urlParser connection URL information's
   * @param lock the lock for thread synchronisation
   * @param traceCache trace cache
   */
  AbstractQueryProtocol(
      final UrlParser urlParser,
      final GlobalStateInfo globalInfo,
      final ReentrantLock lock,
      LruTraceCache traceCache) {
    super(urlParser, globalInfo, lock, traceCache);
  }

  /**
   * Reset connection state.
   *
   * <ol>
   *   <li>Transaction will be rollback
   *   <li>transaction isolation will be reset
   *   <li>user variables will be removed
   *   <li>sessions variables will be reset to global values
   * </ol>
   *
   * @throws SQLException if command failed
   */
  @Override
  public void reset() throws SQLException {
    cmdPrologue();
    try {

      writer.startPacket(0);
      writer.write(COM_RESET_CONNECTION);
      writer.flush();
      getResult(new Results());

      // clear prepare statement cache
      if (options.cachePrepStmts && options.useServerPrepStmts) {
        serverPrepareStatementCache.clear();
      }

    } catch (SQLException sqlException) {
      throw exceptionWithQuery("COM_RESET_CONNECTION failed.", sqlException, explicitClosed);
    } catch (IOException e) {
      throw exceptionWithQuery(
          "COM_RESET_CONNECTION failed.", handleIoException(e), explicitClosed);
    }
  }

  private MariaDbSqlException exceptionWithQuery(
      ParameterHolder[] parameters,
      PrepareResult serverPrepareResult,
      SQLException sqlException,
      boolean explicitClosed) {
    return exceptionWithQuery(
        LogQueryTool.queryWithParams(serverPrepareResult, parameters, options),
        sqlException,
        explicitClosed);
  }

  private MariaDbSqlException exceptionWithQuery(
      String sql, SQLException sqlException, boolean explicitClosed) {
    MariaDbSqlException ex;
    if (explicitClosed) {
      ex =
          new MariaDbSqlException(
              "Connection has explicitly been closed/aborted.", sql, sqlException);
    } else {
      if (sqlException.getCause() instanceof SocketTimeoutException) {
        ex = new MariaDbSqlException("Connection timed out", sql, "08000", sqlException);
      } else {
        ex = MariaDbSqlException.of(sqlException, sql);
      }
    }

    if (options.includeThreadDumpInDeadlockExceptions || sqlException.getErrorCode() == 1064) {
      ex.withThreadName(Thread.currentThread().getName());
    }

    // Add innoDB status if asked
    if (options.includeInnodbStatusInDeadlockExceptions
        && sqlException.getSQLState() != null
        && LOCK_DEADLOCK_ERROR_CODES.contains(sqlException.getErrorCode())) {
      try {
        lock.lock();
        cmdPrologue();
        Results results = new Results();
        executeQuery(isMasterConnection(), results, "SHOW ENGINE INNODB STATUS");
        results.commandEnd();
        ResultSet rs = results.getResultSet();
        if (rs.next()) {
          return ex.withDeadLockInfo(rs.getString(3));
        }
      } catch (SQLException sqle) {
        // eat
      } finally {
        lock.unlock();
      }
    }
    return ex;
  }

  /**
   * Execute internal query.
   *
   * <p>!! will not support multi values queries !!
   *
   * @param sql sql
   * @throws SQLException in any exception occur
   */
  public void executeQuery(final String sql) throws SQLException {
    executeQuery(isMasterConnection(), new Results(), sql);
  }

  /**
   * Execute query directly to outputStream.
   *
   * @param mustExecuteOnMaster was intended to be launched on master connection
   * @param results result
   * @param sql the query to executeInternal
   * @throws SQLException exception
   */
  @Override
  public void executeQuery(boolean mustExecuteOnMaster, Results results, final String sql)
      throws SQLException {

    cmdPrologue();
    try {

      writer.startPacket(0);
      writer.write(COM_QUERY);
      writer.write(sql);
      writer.flush();
      getResult(results);

    } catch (SQLException sqlException) {
      if ("70100".equals(sqlException.getSQLState()) && 1927 == sqlException.getErrorCode()) {
        throw handleIoException(sqlException);
      }
      throw exceptionWithQuery(sql, sqlException, explicitClosed);
    } catch (IOException e) {
      throw exceptionWithQuery(sql, handleIoException(e), explicitClosed);
    }
  }

  @Override
  public void executeQuery(
      boolean mustExecuteOnMaster, Results results, final String sql, Charset charset)
      throws SQLException {
    cmdPrologue();
    try {

      writer.startPacket(0);
      writer.write(COM_QUERY);
      writer.write(sql.getBytes(charset));
      writer.flush();
      getResult(results);

    } catch (SQLException sqlException) {
      throw exceptionWithQuery(sql, sqlException, explicitClosed);
    } catch (IOException e) {
      throw exceptionWithQuery(sql, handleIoException(e), explicitClosed);
    }
  }

  /**
   * Execute a unique clientPrepareQuery.
   *
   * @param mustExecuteOnMaster was intended to be launched on master connection
   * @param results results
   * @param clientPrepareResult clientPrepareResult
   * @param parameters parameters
   * @throws SQLException exception
   */
  public void executeQuery(
      boolean mustExecuteOnMaster,
      Results results,
      final ClientPrepareResult clientPrepareResult,
      ParameterHolder[] parameters)
      throws SQLException {
    cmdPrologue();
    try {

      if (clientPrepareResult.getParamCount() == 0
          && !clientPrepareResult.isQueryMultiValuesRewritable()) {
        if (clientPrepareResult.getQueryParts().size() == 1) {
          ComQuery.sendDirect(writer, clientPrepareResult.getQueryParts().get(0));
        } else {
          ComQuery.sendMultiDirect(writer, clientPrepareResult.getQueryParts());
        }
      } else {
        writer.startPacket(0);
        ComQuery.sendSubCmd(writer, clientPrepareResult, parameters, -1);
        writer.flush();
      }
      getResult(results);

    } catch (SQLException queryException) {
      throw exceptionWithQuery(parameters, clientPrepareResult, queryException, false);
    } catch (IOException e) {
      throw exceptionWithQuery(parameters, clientPrepareResult, handleIoException(e), false);
    }
  }

  /**
   * Execute a unique clientPrepareQuery.
   *
   * @param mustExecuteOnMaster was intended to be launched on master connection
   * @param results results
   * @param clientPrepareResult clientPrepareResult
   * @param parameters parameters
   * @param queryTimeout if timeout is set and must use max_statement_time
   * @throws SQLException exception
   */
  public void executeQuery(
      boolean mustExecuteOnMaster,
      Results results,
      final ClientPrepareResult clientPrepareResult,
      ParameterHolder[] parameters,
      int queryTimeout)
      throws SQLException {
    cmdPrologue();
    try {

      if (clientPrepareResult.getParamCount() == 0
          && !clientPrepareResult.isQueryMultiValuesRewritable()) {
        if (clientPrepareResult.getQueryParts().size() == 1) {
          ComQuery.sendDirect(writer, clientPrepareResult.getQueryParts().get(0), queryTimeout);
        } else {
          ComQuery.sendMultiDirect(writer, clientPrepareResult.getQueryParts(), queryTimeout);
        }
      } else {
        writer.startPacket(0);
        ComQuery.sendSubCmd(writer, clientPrepareResult, parameters, queryTimeout);
        writer.flush();
      }
      getResult(results);

    } catch (SQLException queryException) {
      throw exceptionWithQuery(parameters, clientPrepareResult, queryException, false);
    } catch (IOException e) {
      throw exceptionWithQuery(parameters, clientPrepareResult, handleIoException(e), false);
    }
  }

  /**
   * Execute clientPrepareQuery batch.
   *
   * @param mustExecuteOnMaster was intended to be launched on master connection
   * @param results results
   * @param prepareResult ClientPrepareResult
   * @param parametersList List of parameters
   * @throws SQLException exception
   */
  public boolean executeBatchClient(
      boolean mustExecuteOnMaster,
      Results results,
      final ClientPrepareResult prepareResult,
      final List<ParameterHolder[]> parametersList)
      throws SQLException {

    // ***********************************************************************************************************
    // Multiple solution for batching :
    // - rewrite as multi-values (only if generated keys are not needed and query can be rewritten)
    // - multiple INSERT separate by semi-columns
    // - use pipeline
    // - use bulk
    // - one after the other
    // ***********************************************************************************************************

    if (options.rewriteBatchedStatements && prepareResult.isQueryMultiValuesRewritable()) {
      if (results.getAutoGeneratedKeys() == Statement.NO_GENERATED_KEYS) {

        // values rewritten in one query :
        // INSERT INTO X(a,b) VALUES (1,2), (3,4), ...
        executeBatchRewrite(results, prepareResult, parametersList, true);
        return true;
      }

      if (options.useBulkStmts
          && results.getAutoGeneratedKeys() == Statement.NO_GENERATED_KEYS
          && executeBulkBatch(results, prepareResult.getSql(), null, parametersList)) {
        return true;
      }

      // multi rewritten in one query :
      // INSERT INTO X(a,b) VALUES (1,2);INSERT INTO X(a,b) VALUES (3,4); ...
      executeBatchRewrite(results, prepareResult, parametersList, false);
      return true;
    }

    if (options.useBulkStmts
        && results.getAutoGeneratedKeys() == Statement.NO_GENERATED_KEYS
        && executeBulkBatch(results, prepareResult.getSql(), null, parametersList)) {
      return true;
    }

    if (options.useBatchMultiSend) {
      // send by bulk : send data by bulk before reading corresponding results
      executeBatchMulti(results, prepareResult, parametersList);
      return true;
    }

    return false;
  }

  /**
   * Execute clientPrepareQuery batch.
   *
   * @param results results
   * @param sql sql command
   * @param serverPrepareResult prepare result if exist
   * @param parametersList List of parameters
   * @return if executed
   * @throws SQLException exception
   */
  private boolean executeBulkBatch(
      Results results,
      String sql,
      ServerPrepareResult serverPrepareResult,
      final List<ParameterHolder[]> parametersList)
      throws SQLException {

    // **************************************************************************************
    // Ensure BULK can be use :
    // - server support bulk
    // - parameter type doesn't change
    // - avoid INSERT FROM SELECT
    // **************************************************************************************
    if ((serverCapabilities & MariaDbServerCapabilities.MARIADB_CLIENT_STMT_BULK_OPERATIONS) == 0)
      return false;

    // ensure that type doesn't change
    ParameterHolder[] initParameters = parametersList.get(0);
    int parameterCount = initParameters.length;
    short[] types = new short[parameterCount];
    for (int i = 0; i < parameterCount; i++) {
      types[i] = initParameters[i].getColumnType().getType();
    }
    for (ParameterHolder[] parameters : parametersList) {
      for (int i = 0; i < parameterCount; i++) {
        if (parameters[i].getColumnType().getType() != types[i]
            && parameters[i].getColumnType() != ColumnType.NULL) {
          return false;
        }
      }
    }

    // any select query is not applicable to bulk
    if (sql.toLowerCase(Locale.ROOT).contains("select")) {
      return false;
    }

    cmdPrologue();
    ParameterHolder[] parameters = null;
    ServerPrepareResult tmpServerPrepareResult = serverPrepareResult;
    try {
      SQLException exception = null;

      // **************************************************************************************
      // send PREPARE if needed
      // **************************************************************************************
      if (serverPrepareResult == null) {
        tmpServerPrepareResult = prepare(sql, true);
      }

      // **************************************************************************************
      // send BULK
      // **************************************************************************************
      int statementId =
          tmpServerPrepareResult != null ? tmpServerPrepareResult.getStatementId() : -1;

      byte[] lastCmdData = null;
      int index = 0;
      ParameterHolder[] firstParameters = parametersList.get(0);

      do {
        writer.startPacket(0);
        writer.write(COM_STMT_BULK_EXECUTE);
        writer.writeInt(statementId);
        writer.writeShort((short) 128); // always SEND_TYPES_TO_SERVER

        for (ParameterHolder param : firstParameters) {
          writer.writeShort(param.getColumnType().getType());
        }

        if (lastCmdData != null) {
          writer.checkMaxAllowedLength(lastCmdData.length);
          writer.write(lastCmdData);
          writer.mark();
          index++;
          lastCmdData = null;
        }

        for (; index < parametersList.size(); index++) {
          parameters = parametersList.get(index);
          for (int i = 0; i < parameterCount; i++) {
            ParameterHolder holder = parameters[i];
            if (holder.isNullData()) {
              writer.write(1); // NULL
            } else {
              writer.write(0); // NONE
              holder.writeBinary(writer);
            }
          }

          // if buffer > MAX_ALLOWED_PACKET, flush until last mark.
          if (writer.exceedMaxLength() && writer.isMarked()) {
            writer.flushBufferStopAtMark();
          }

          // if flushed, quit loop
          if (writer.bufferIsDataAfterMark()) {
            break;
          }

          writer.checkMaxAllowedLength(0);
          writer.mark();
        }

        if (writer.bufferIsDataAfterMark()) {
          // flush has been done
          lastCmdData = writer.resetMark();
        } else {
          writer.flush();
          writer.resetMark();
        }

        try {
          getResult(results);
        } catch (SQLException sqle) {
          if ("HY000".equals(sqle.getSQLState()) && sqle.getErrorCode() == 1295) {
            // query contain commands that cannot be handled by BULK protocol
            // clear error and special error code, so it won't leak anywhere
            // and wouldn't be misinterpreted as an additional update count
            results.getCmdInformation().reset();
            return false;
          }
          if (exception == null) {
            exception = exceptionWithQuery(sql, sqle, explicitClosed);
            if (!options.continueBatchOnError) {
              throw exception;
            }
          }
        }

      } while (index < parametersList.size() - 1);

      if (lastCmdData != null) {
        writer.startPacket(0);
        writer.write(COM_STMT_BULK_EXECUTE);
        writer.writeInt(statementId);
        writer.writeShort((byte) 0x80); // always SEND_TYPES_TO_SERVER

        for (ParameterHolder param : firstParameters) {
          writer.writeShort(param.getColumnType().getType());
        }
        writer.write(lastCmdData);
        writer.flush();
        try {
          getResult(results);
        } catch (SQLException sqle) {
          if ("HY000".equals(sqle.getSQLState()) && sqle.getErrorCode() == 1295) {
            // query contain SELECT. cannot be handle by BULK protocol
            return false;
          }
          if (exception == null) {
            exception = exceptionWithQuery(sql, sqle, explicitClosed);
            if (!options.continueBatchOnError) {
              throw exception;
            }
          }
        }
      }

      if (exception != null) {
        throw exception;
      }
      results.setRewritten(true);
      return true;

    } catch (IOException e) {
      throw exceptionWithQuery(
          parameters, tmpServerPrepareResult, handleIoException(e), explicitClosed);
    } finally {
      if (serverPrepareResult == null && tmpServerPrepareResult != null) {
        releasePrepareStatement(tmpServerPrepareResult);
      }
      writer.resetMark();
    }
  }

  private void initializeBatchReader() {
    if (options.useBatchMultiSend) {
      readScheduler = SchedulerServiceProviderHolder.getBulkScheduler();
    }
  }

  /**
   * Execute clientPrepareQuery batch.
   *
   * @param results results
   * @param clientPrepareResult ClientPrepareResult
   * @param parametersList List of parameters
   * @throws SQLException exception
   */
  private void executeBatchMulti(
      Results results,
      final ClientPrepareResult clientPrepareResult,
      final List<ParameterHolder[]> parametersList)
      throws SQLException {

    cmdPrologue();
    initializeBatchReader();
    new AbstractMultiSend(
        this, writer, results, clientPrepareResult, parametersList, readScheduler) {

      @Override
      public void sendCmd(
          PacketOutputStream writer,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int paramCount,
          BulkStatus status,
          PrepareResult prepareResult)
          throws IOException {

        ParameterHolder[] parameters = parametersList.get(status.sendCmdCounter);
        writer.startPacket(0);
        ComQuery.sendSubCmd(writer, clientPrepareResult, parameters, -1);
        writer.flush();
      }

      @Override
      public SQLException handleResultException(
          SQLException qex,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int currentCounter,
          int sendCmdCounter,
          int paramCount,
          PrepareResult prepareResult) {

        int counter = results.getCurrentStatNumber() - 1;
        ParameterHolder[] parameters = parametersList.get(counter);
        List<byte[]> queryParts = clientPrepareResult.getQueryParts();

        StringBuilder sql;
        if (clientPrepareResult.isRewriteType()) {
          // build sql from rewrite parsing
          sql = new StringBuilder(new String(queryParts.get(0)));
          sql.append(new String(queryParts.get(1)));
          for (int i = 0; i < paramCount; i++) {
            sql.append(parameters[i].toString()).append(new String(queryParts.get(i + 2)));
          }
          sql.append(new String(queryParts.get(paramCount + 2)));
        } else {
          // build sql from basic parsing
          sql = new StringBuilder(new String(queryParts.get(0)));
          for (int i = 0; i < paramCount; i++) {
            sql.append(parameters[i].toString()).append(new String(queryParts.get(i + 1)));
          }
        }

        return exceptionWithQuery(sql.toString(), qex, explicitClosed);
      }

      @Override
      public int getParamCount() {
        return clientPrepareResult.getParamCount();
      }

      @Override
      public int getTotalExecutionNumber() {
        return parametersList.size();
      }
    }.executeBatch();
  }

  /**
   * Execute batch from Statement.executeBatch().
   *
   * @param mustExecuteOnMaster was intended to be launched on master connection
   * @param results results
   * @param queries queries
   * @throws SQLException if any exception occur
   */
  public void executeBatchStmt(
      boolean mustExecuteOnMaster, Results results, final List<String> queries)
      throws SQLException {
    cmdPrologue();
    if (this.options.rewriteBatchedStatements) {

      // check that queries are rewritable
      boolean canAggregateSemiColumn = true;
      for (String query : queries) {
        if (!ClientPrepareResult.canAggregateSemiColon(query, noBackslashEscapes())) {
          canAggregateSemiColumn = false;
          break;
        }
      }

      if (isInterrupted()) {
        // interrupted by timeout, must throw an exception manually
        throw new SQLTimeoutException("Timeout during batch execution");
      }

      if (canAggregateSemiColumn) {
        executeBatchAggregateSemiColon(results, queries);
      } else {
        executeBatch(results, queries);
      }

    } else {
      executeBatch(results, queries);
    }
  }

  /**
   * Execute list of queries not rewritable.
   *
   * @param results result object
   * @param queries list of queries
   * @throws SQLException exception
   */
  private void executeBatch(Results results, final List<String> queries) throws SQLException {

    // Ensure not having load local infile
    boolean usePipeline = options.useBatchMultiSend;
    if (usePipeline) {
      for (int i = 0; i < queries.size(); i++) {
        if (LOAD_LOCAL_INFILE.matcher(queries.get(i)).find()) {
          usePipeline = false;
          break;
        }
      }
    }

    if (!usePipeline) {

      String sql = null;
      SQLException exception = null;

      for (int i = 0; i < queries.size() && !isInterrupted(); i++) {

        try {

          sql = queries.get(i);
          writer.startPacket(0);
          writer.write(COM_QUERY);
          writer.write(sql);
          writer.flush();
          getResult(results);

        } catch (SQLException sqlException) {
          if (exception == null) {
            exception = exceptionWithQuery(sql, sqlException, explicitClosed);
            if (!options.continueBatchOnError) {
              throw exception;
            }
          }
        } catch (IOException e) {
          if (exception == null) {
            exception = exceptionWithQuery(sql, handleIoException(e), explicitClosed);
            if (!options.continueBatchOnError) {
              throw exception;
            }
          }
        }
      }
      stopIfInterrupted();

      if (exception != null) {
        throw exception;
      }
      return;
    }
    initializeBatchReader();
    new AbstractMultiSend(this, writer, results, queries, readScheduler) {

      @Override
      public void sendCmd(
          PacketOutputStream pos,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int paramCount,
          BulkStatus status,
          PrepareResult prepareResult)
          throws IOException {

        String sql = queries.get(status.sendCmdCounter);
        pos.startPacket(0);
        pos.write(COM_QUERY);
        pos.write(sql);
        pos.flush();
      }

      @Override
      public SQLException handleResultException(
          SQLException qex,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int currentCounter,
          int sendCmdCounter,
          int paramCount,
          PrepareResult prepareResult) {

        String sql = queries.get(currentCounter + sendCmdCounter);
        return exceptionWithQuery(sql, qex, explicitClosed);
      }

      @Override
      public int getParamCount() {
        return -1;
      }

      @Override
      public int getTotalExecutionNumber() {
        return queries.size();
      }
    }.executeBatch();
  }

  /**
   * Prepare query on server side. Will permit to know the parameter number of the query, and permit
   * to send only the data on next results.
   *
   * <p>For failover, two additional information are in the result-set object : - current connection
   * : Since server maintain a state of this prepare statement, all query will be executed on this
   * particular connection. - executeOnMaster : state of current connection when creating this
   * prepareStatement (if was on master, will only be executed on master. If was on a replica, can
   * be execute temporary on master, but we keep this flag, so when a replica is connected back to
   * relaunch this query on replica)
   *
   * @param sql the query
   * @param executeOnMaster state of current connection when creating this prepareStatement
   * @return a ServerPrepareResult object that contain prepare result information.
   * @throws SQLException if any error occur on connection.
   */
  @Override
  public ServerPrepareResult prepare(String sql, boolean executeOnMaster) throws SQLException {

    lock.lock();
    try {
      // search in cache first
      if (options.cachePrepStmts && options.useServerPrepStmts) {
        ServerPrepareResult pr = serverPrepareStatementCache.get(database + "-" + sql);
        if (pr != null && pr.incrementShareCounter()) {
          return pr;
        }
      }

      cmdPrologue();

      return new ComStmtPrepare(this, sql).send(writer).read(reader, eofDeprecated);

    } catch (IOException e) {
      throw exceptionWithQuery(sql, handleIoException(e), explicitClosed);
    } finally {
      lock.unlock();
    }
  }

  /**
   * Execute list of queries. This method is used when using text batch statement and using
   * rewriting (allowMultiQueries || rewriteBatchedStatements). queries will be send to server
   * according to max_allowed_packet size.
   *
   * @param results result object
   * @param queries list of queries
   * @throws SQLException exception
   */
  private void executeBatchAggregateSemiColon(Results results, final List<String> queries)
      throws SQLException {

    String firstSql = null;
    int currentIndex = 0;
    int totalQueries = queries.size();
    SQLException exception = null;

    do {

      try {

        firstSql = queries.get(currentIndex++);

        if (totalQueries == 1) {
          writer.startPacket(0);
          writer.write(COM_QUERY);
          writer.write(firstSql);
          writer.flush();
        } else {
          currentIndex =
              ComQuery.sendBatchAggregateSemiColon(writer, firstSql, queries, currentIndex);
        }
        getResult(results);

      } catch (SQLException sqlException) {
        if (exception == null) {
          exception = exceptionWithQuery(firstSql, sqlException, explicitClosed);
          if (!options.continueBatchOnError) {
            throw exception;
          }
        }
      } catch (IOException e) {
        throw exceptionWithQuery(firstSql, handleIoException(e), explicitClosed);
      }
      stopIfInterrupted();

    } while (currentIndex < totalQueries);

    if (exception != null) {
      throw exception;
    }
  }

  /**
   * Specific execution for batch rewrite that has specific query for memory.
   *
   * @param results result
   * @param prepareResult prepareResult
   * @param parameterList parameters
   * @param rewriteValues is rewritable flag
   * @throws SQLException exception
   */
  private void executeBatchRewrite(
      Results results,
      final ClientPrepareResult prepareResult,
      List<ParameterHolder[]> parameterList,
      boolean rewriteValues)
      throws SQLException {

    cmdPrologue();

    int currentIndex = 0;
    int totalParameterList = parameterList.size();

    try {

      do {

        currentIndex =
            ComQuery.sendRewriteCmd(
                writer,
                prepareResult.getQueryParts(),
                currentIndex,
                prepareResult.getParamCount(),
                parameterList,
                rewriteValues);
        getResult(results);

        if (Thread.currentThread().isInterrupted()) {
          throw new SQLException(
              "Interrupted during batch", INTERRUPTED_EXCEPTION.getSqlState(), -1);
        }

      } while (currentIndex < totalParameterList);

    } catch (SQLException sqlEx) {
      throw MariaDbSqlException.of(sqlEx, prepareResult.getSql());
    } catch (IOException e) {
      throw exceptionWithQuery(
          parameterList.get(currentIndex), prepareResult, handleIoException(e), explicitClosed);
    } finally {
      results.setRewritten(rewriteValues);
    }
  }

  /**
   * Execute Prepare if needed, and execute COM_STMT_EXECUTE queries in batch.
   *
   * @param mustExecuteOnMaster must normally be executed on master connection
   * @param serverPrepareResult prepare result. can be null if not prepared.
   * @param results execution results
   * @param sql sql query if needed to be prepared
   * @param parametersList parameter list
   * @return executed
   * @throws SQLException if parameter error or connection error occur.
   */
  public boolean executeBatchServer(
      boolean mustExecuteOnMaster,
      ServerPrepareResult serverPrepareResult,
      Results results,
      String sql,
      final List<ParameterHolder[]> parametersList)
      throws SQLException {

    cmdPrologue();

    if (options.useBulkStmts
        && results.getAutoGeneratedKeys() == Statement.NO_GENERATED_KEYS
        && executeBulkBatch(results, sql, serverPrepareResult, parametersList)) {
      return true;
    }

    if (!options.useBatchMultiSend) {
      return false;
    }
    initializeBatchReader();
    new AbstractMultiSend(
        this, writer, results, serverPrepareResult, parametersList, sql, readScheduler) {
      @Override
      public void sendCmd(
          PacketOutputStream writer,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int paramCount,
          BulkStatus status,
          PrepareResult prepareResult)
          throws SQLException, IOException {

        ParameterHolder[] parameters = parametersList.get(status.sendCmdCounter);

        // validate parameter set
        if (parameters.length < paramCount) {
          throw new SQLException(
              "Parameter at position " + (paramCount - 1) + " is not set", "07004");
        }

        // send binary data in a separate stream
        for (int i = 0; i < paramCount; i++) {
          if (parameters[i].canBeLongData()) {
            writer.startPacket(0);
            writer.write(COM_STMT_SEND_LONG_DATA);
            writer.writeInt(statementId);
            writer.writeShort((short) i);
            parameters[i].writeLongData(writer);
            writer.flush();
          }
        }

        writer.startPacket(0);
        ComStmtExecute.writeCmd(
            statementId,
            parameters,
            paramCount,
            parameterTypeHeader,
            writer,
            CURSOR_TYPE_NO_CURSOR);
        writer.flush();
      }

      @Override
      public SQLException handleResultException(
          SQLException qex,
          Results results,
          List<ParameterHolder[]> parametersList,
          List<String> queries,
          int currentCounter,
          int sendCmdCounter,
          int paramCount,
          PrepareResult prepareResult) {
        return MariaDbSqlException.of(qex, prepareResult.getSql());
      }

      @Override
      public int getParamCount() {
        return serverPrepareResult.getParameters().length;
      }

      @Override
      public int getTotalExecutionNumber() {
        return parametersList.size();
      }
    }.executeBatch();
    return true;
  }

  /**
   * Execute a query that is already prepared.
   *
   * @param mustExecuteOnMaster must execute on master
   * @param serverPrepareResult prepare result
   * @param results execution result
   * @param parameters parameters
   * @throws SQLException exception
   */
  @Override
  public void executePreparedQuery(
      boolean mustExecuteOnMaster,
      ServerPrepareResult serverPrepareResult,
      Results results,
      ParameterHolder[] parameters)
      throws SQLException {

    cmdPrologue();

    try {

      int parameterCount = serverPrepareResult.getParameters().length;

      // send binary data in a separate stream
      for (int i = 0; i < parameterCount && i < parameters.length; i++) {
        if (parameters[i].canBeLongData()) {
          writer.startPacket(0);
          writer.write(COM_STMT_SEND_LONG_DATA);
          writer.writeInt(serverPrepareResult.getStatementId());
          writer.writeShort((short) i);
          parameters[i].writeLongData(writer);
          writer.flush();
        }
      }

      // send execute query
      ComStmtExecute.send(
          writer,
          serverPrepareResult.getStatementId(),
          parameters,
          parameterCount,
          serverPrepareResult.getParameterTypeHeader(),
          CURSOR_TYPE_NO_CURSOR);
      getResult(results);

    } catch (SQLException qex) {
      throw exceptionWithQuery(parameters, serverPrepareResult, qex, false);
    } catch (IOException e) {
      throw exceptionWithQuery(parameters, serverPrepareResult, handleIoException(e), false);
    }
  }

  /** Rollback transaction. */
  public void rollback() throws SQLException {

    cmdPrologue();

    lock.lock();
    try {

      if (inTransaction()) {
        executeQuery("ROLLBACK");
      }

    } catch (Exception e) {
      /* eat exception */
    } finally {
      lock.unlock();
    }
  }

  /**
   * Force release of prepare statement that are not used. This method will be call when adding a
   * new prepare statement in cache, so the packet can be send to server without problem.
   *
   * @param statementId prepared statement Id to remove.
   * @return true if successfully released
   * @throws SQLException if connection exception.
   */
  public boolean forceReleasePrepareStatement(int statementId) throws SQLException {

    if (lock.tryLock()) {

      try {

        checkClose();

        try {
          writer.startPacket(0);
          writer.write(COM_STMT_CLOSE);
          writer.writeInt(statementId);
          writer.flush();
          return true;
        } catch (IOException e) {
          connected = false;
          throw new SQLNonTransientConnectionException(
              "Could not deallocate query: " + e.getMessage(), "08000", e);
        }

      } finally {
        lock.unlock();
      }

    } else {
      // lock is used by another thread (bulk reading)
      statementIdToRelease = statementId;
    }

    return false;
  }

  /**
   * Force release of prepare statement that are not used. This permit to deallocate a statement
   * that cannot be release due to multi-thread use.
   *
   * @throws SQLException if connection occur
   */
  public void forceReleaseWaitingPrepareStatement() throws SQLException {
    if (statementIdToRelease != -1 && forceReleasePrepareStatement(statementIdToRelease)) {
      statementIdToRelease = -1;
    }
  }

  @Override
  public boolean ping() throws SQLException {

    cmdPrologue();
    lock.lock();
    try {

      writer.startPacket(0);
      writer.write(COM_PING);
      writer.flush();

      Buffer buffer = reader.getPacket(true);
      return buffer.getByteAt(0) == OK;

    } catch (IOException e) {
      connected = false;
      throw new SQLNonTransientConnectionException(
          "Could not ping connection " + serverThreadId + " : " + e.getMessage(), "08000", e);
    } finally {
      lock.unlock();
    }
  }

  /**
   * Check that connection is valid. !! careful, timeout is in milliseconds,
   * connection.isValid(timeout) is in seconds !!
   *
   * @param timeout timeout in milliseconds
   * @return true is valid
   * @throws SQLException if any error occur
   */
  @Override
  public boolean isValid(int timeout) throws SQLException {

    int initialTimeout = -1;
    try {
      initialTimeout = this.socketTimeout;
      if (initialTimeout == 0) {
        this.changeSocketSoTimeout(timeout);
      }
      if (isMasterConnection() && !galeraAllowedStates.isEmpty()) {
        // this is a galera node.
        // checking not only that node is responding, but that galera state is allowed.
        Results results = new Results();
        executeQuery(true, results, CHECK_GALERA_STATE_QUERY);
        results.commandEnd();
        ResultSet rs = results.getResultSet();

        return rs != null && rs.next() && galeraAllowedStates.contains(rs.getString(2));
      }

      return ping();

    } catch (SocketException socketException) {
      logger.trace("Connection is not valid", socketException);
      connected = false;
      return false;
    } finally {

      // set back initial socket timeout
      try {
        if (initialTimeout != -1) {
          this.changeSocketSoTimeout(initialTimeout);
        }
      } catch (SocketException socketException) {
        logger.warn("Could not set socket timeout back to " + initialTimeout, socketException);
        connected = false;
        // eat
      }
    }
  }

  @Override
  public String getCatalog() throws SQLException {

    if ((serverCapabilities & MariaDbServerCapabilities.CLIENT_SESSION_TRACK) != 0) {
      // client session track return empty value, not null value. Java require sending null if empty
      if (database != null && database.isEmpty()) {
        return null;
      }
      return database;
    }

    cmdPrologue();
    lock.lock();
    try {
      Results results = new Results();
      executeQuery(isMasterConnection(), results, "select database()");
      results.commandEnd();
      ResultSet rs = results.getResultSet();
      if (rs.next()) {
        this.database = rs.getString(1);
        return database;
      }
      return null;
    } finally {
      lock.unlock();
    }
  }

  @Override
  public void setCatalog(final String database) throws SQLException {

    cmdPrologue();

    lock.lock();
    try {

      SendChangeDbPacket.send(writer, database);
      final Buffer buffer = reader.getPacket(true);

      if (buffer.getByteAt(0) == ERROR) {
        final ErrorPacket ep = new ErrorPacket(buffer);
        throw new SQLException(
            "Could not select database '" + database + "' : " + ep.getMessage(),
            ep.getSqlState(),
            ep.getErrorCode());
      }

      this.database = database;

    } catch (IOException e) {
      throw exceptionWithQuery("COM_INIT_DB", handleIoException(e), false);
    } finally {
      lock.unlock();
    }
  }

  @Override
  public void resetDatabase() throws SQLException {
    if (!database.equals(urlParser.getDatabase())) {
      setCatalog(urlParser.getDatabase());
    }
  }

  /**
   * Cancels the current query - clones the current protocol and executes a query using the new
   * connection.
   *
   * @throws SQLException never thrown
   */
  @Override
  public void cancelCurrentQuery() throws SQLException {
    try (MasterProtocol copiedProtocol =
        new MasterProtocol(urlParser, new GlobalStateInfo(), new ReentrantLock(), traceCache)) {
      HostAddress currentHost = getHostAddress();
      String currentIp = getSocketIp();
      HostAddress hostAddress =
          currentIp == null
              ? currentHost
              : new HostAddress(currentIp, currentHost.port, currentHost.type);
      copiedProtocol.setHostAddress(hostAddress);
      copiedProtocol.connect();
      // no lock, because there is already a query running that possessed the lock.
      copiedProtocol.executeQuery("KILL QUERY " + serverThreadId);
    }
    interrupted = true;
  }

  /**
   * Get current autocommit status.
   *
   * @return autocommit status
   */
  @Override
  public boolean getAutocommit() {
    return ((serverStatus & ServerStatus.AUTOCOMMIT) != 0);
  }

  @Override
  public boolean inTransaction() {
    return ((serverStatus & ServerStatus.IN_TRANSACTION) != 0);
  }

  public void closeExplicit() {
    this.explicitClosed = true;
    close();
  }

  /**
   * Deallocate prepare statement if not used anymore.
   *
   * @param serverPrepareResult allocation result
   * @throws SQLException if de-allocation failed.
   */
  @Override
  public void releasePrepareStatement(ServerPrepareResult serverPrepareResult) throws SQLException {
    // If prepared cache is enable, the ServerPrepareResult can be shared in many PrepStatement,
    // so synchronised use count indicator will be decrement.
    serverPrepareResult.decrementShareCounter();

    // deallocate from server if not cached
    if (serverPrepareResult.canBeDeallocate()) {
      forceReleasePrepareStatement(serverPrepareResult.getStatementId());
    }
  }

  public long getMaxRows() {
    return maxRows;
  }

  @Override
  public void setMaxRows(long max) throws SQLException {
    if (maxRows != max) {
      if (max == 0) {
        executeQuery("set @@SQL_SELECT_LIMIT=DEFAULT");
      } else {
        executeQuery("set @@SQL_SELECT_LIMIT=" + max);
      }
      maxRows = max;
    }
  }

  @Override
  public void setLocalInfileInputStream(InputStream inputStream) {
    this.localInfileInputStream = inputStream;
  }

  /**
   * Returns the connection timeout in milliseconds.
   *
   * @return the connection timeout in milliseconds.
   */
  @Override
  public int getTimeout() {
    return this.socketTimeout;
  }

  /**
   * Sets the connection timeout.
   *
   * @param timeout the timeout, in milliseconds
   * @throws SocketException if there is an error in the underlying protocol, such as a TCP error.
   */
  @Override
  public void setTimeout(int timeout) throws SocketException {
    lock.lock();
    try {
      this.changeSocketSoTimeout(timeout);
    } finally {
      lock.unlock();
    }
  }

  /**
   * Puts this connection in read-only / read-write mode
   *
   * @param readOnly true enables read-only mode; false disables it
   * @throws SQLException If socket error.
   */
  public void setReadonly(final boolean readOnly) throws SQLException {
    if (options.assureReadOnly && this.readOnly != readOnly && versionGreaterOrEqual(5, 6, 5)) {
      executeQuery("SET SESSION TRANSACTION " + (readOnly ? "READ ONLY" : "READ WRITE"));
    }
    this.readOnly = readOnly;
  }

  /**
   * Set transaction isolation.
   *
   * @param level transaction level.
   * @throws SQLException if transaction level is unknown
   */
  public void setTransactionIsolation(final int level) throws SQLException {
    cmdPrologue();
    lock.lock();
    try {
      String query = "SET SESSION TRANSACTION ISOLATION LEVEL";
      switch (level) {
        case Connection.TRANSACTION_READ_UNCOMMITTED:
          query += " READ UNCOMMITTED";
          break;
        case Connection.TRANSACTION_READ_COMMITTED:
          query += " READ COMMITTED";
          break;
        case Connection.TRANSACTION_REPEATABLE_READ:
          query += " REPEATABLE READ";
          break;
        case Connection.TRANSACTION_SERIALIZABLE:
          query += " SERIALIZABLE";
          break;
        default:
          throw new SQLException("Unsupported transaction isolation level");
      }
      executeQuery(query);
      transactionIsolationLevel = level;
    } finally {
      lock.unlock();
    }
  }

  public int getTransactionIsolationLevel() {
    return transactionIsolationLevel;
  }

  private void checkClose() throws SQLException {
    if (!this.connected) {
      throw new SQLException("Connection is close", "08000", 1220);
    }
  }

  @Override
  public void getResult(Results results) throws SQLException {

    readPacket(results);

    // load additional results
    while (hasMoreResults()) {
      readPacket(results);
    }
  }

  /**
   * Read server response packet.
   *
   * @param results result object
   * @throws SQLException if sub-result connection fail
   * @see <a href="https://mariadb.com/kb/en/mariadb/4-server-response-packets/">server response
   *     packets</a>
   */
  private void readPacket(Results results) throws SQLException {
    Buffer buffer;
    try {
      buffer = reader.getPacket(true);
    } catch (IOException e) {
      throw handleIoException(e);
    }

    switch (buffer.getByteAt(0)) {

        // *********************************************************************************************************
        // * OK response
        // *********************************************************************************************************
      case OK:
        readOkPacket(buffer, results);
        break;

        // *********************************************************************************************************
        // * ERROR response
        // *********************************************************************************************************
      case ERROR:
        throw readErrorPacket(buffer, results);

        // *********************************************************************************************************
        // * LOCAL INFILE response
        // *********************************************************************************************************
      case LOCAL_INFILE:
        readLocalInfilePacket(buffer, results);
        break;

        // *********************************************************************************************************
        // * ResultSet
        // *********************************************************************************************************
      default:
        readResultSet(buffer, results);
        break;
    }
  }

  /**
   * Read OK_Packet.
   *
   * @param buffer current buffer
   * @param results result object
   * @see <a href="https://mariadb.com/kb/en/mariadb/ok_packet/">OK_Packet</a>
   */
  private void readOkPacket(Buffer buffer, Results results) throws SQLException {
    buffer.skipByte(); // fieldCount
    final long updateCount = buffer.getLengthEncodedNumeric();
    final long insertId = buffer.getLengthEncodedNumeric();

    serverStatus = buffer.readShort();
    hasWarnings = (buffer.readShort() > 0);

    if ((serverStatus & ServerStatus.SERVER_SESSION_STATE_CHANGED) != 0) {
      handleStateChange(buffer, results);
    }

    results.addStats(updateCount, insertId, hasMoreResults());
  }

  private void handleStateChange(Buffer buf, Results results) throws SQLException {
    buf.skipLengthEncodedBytes(); // info
    while (buf.remaining() > 0) {
      Buffer stateInfo = buf.getLengthEncodedBuffer();
      while (stateInfo.remaining() > 0) {
        switch (stateInfo.readByte()) {
          case StateChange.SESSION_TRACK_SYSTEM_VARIABLES:
            Buffer sessionVariableBuf;
            do {
              sessionVariableBuf = stateInfo.getLengthEncodedBuffer();
              String variable = sessionVariableBuf.readStringLengthEncoded(StandardCharsets.UTF_8);
              String value = sessionVariableBuf.readStringLengthEncoded(StandardCharsets.UTF_8);
              logger.debug("System variable change :  {} = {}", variable, value);

              // only variable uses
              switch (variable) {
                case "auto_increment_increment":
                  autoIncrementIncrement = Integer.parseInt(value);
                  results.setAutoIncrement(autoIncrementIncrement);
                  break;

                case "maxscale":
                  maxscaleVersion = value;
                  break;

                case "character_set_client":
                  if (value != null && !value.startsWith("utf8")) {
                    destroySocket();
                    throw new SQLNonTransientConnectionException(
                        String.format(
                            "Connection character set was changed to '%s'. Only utf8 / utf8mb3 /"
                                + " utf8mb4 are supported. The connection has been closed.",
                            value),
                        "08000");
                  }
                  break;

                default:
                  // variable not used by driver
              }
            } while (sessionVariableBuf.remaining() > 0);
            break;

          case StateChange.SESSION_TRACK_SCHEMA:
            Buffer sessionSchemaBuf = stateInfo.getLengthEncodedBuffer();
            database = sessionSchemaBuf.readStringLengthEncoded(StandardCharsets.UTF_8);
            logger.debug("Database change : now is '{}'", database);
            break;

          default:
            stateInfo.skipLengthEncodedBytes();
            break;
        }
      }
    }
  }

  /**
   * Get current auto increment increment. *** no lock needed ****
   *
   * @return auto increment increment.
   * @throws SQLException if cannot retrieve auto increment value
   */
  public int getAutoIncrementIncrement() throws SQLException {
    if (autoIncrementIncrement == 0) {
      lock.lock();
      try {
        Results results = new Results();
        executeQuery(true, results, "select @@auto_increment_increment");
        results.commandEnd();
        ResultSet rs = results.getResultSet();
        rs.next();
        autoIncrementIncrement = rs.getInt(1);
      } catch (SQLException e) {
        if (e.getSQLState().startsWith("08")) {
          throw e;
        }
        autoIncrementIncrement = 1;
      } finally {
        lock.unlock();
      }
    }
    return autoIncrementIncrement;
  }

  /**
   * Read ERR_Packet.
   *
   * @param buffer current buffer
   * @param results result object
   * @return SQLException if sub-result connection fail
   * @see <a href="https://mariadb.com/kb/en/mariadb/err_packet/">ERR_Packet</a>
   */
  private SQLException readErrorPacket(Buffer buffer, Results results) {
    removeHasMoreResults();
    this.hasWarnings = false;
    buffer.skipByte();
    final int errorNumber = buffer.readShort();
    String message;
    String sqlState;
    if (buffer.readByte() == '#') {
      sqlState = new String(buffer.readRawBytes(5));
      message = buffer.readStringNullEnd(StandardCharsets.UTF_8);
    } else {
      // Pre-4.1 message, still can be output in newer versions (e.g with 'Too many connections')
      buffer.position -= 1;
      message =
          new String(
              buffer.buf, buffer.position, buffer.limit - buffer.position, StandardCharsets.UTF_8);
      sqlState = "HY000";
    }
    results.addStatsError(false);

    // force current status to in transaction to ensure rollback/commit, since command may have
    // issue a transaction
    serverStatus |= ServerStatus.IN_TRANSACTION;

    removeActiveStreamingResult();
    return new SQLException(message, sqlState, errorNumber);
  }

  /**
   * Read Local_infile Packet.
   *
   * @param buffer current buffer
   * @param results result object
   * @throws SQLException if sub-result connection fail
   * @see <a href="https://mariadb.com/kb/en/mariadb/local_infile-packet/">local_infile packet</a>
   */
  private void readLocalInfilePacket(Buffer buffer, Results results) throws SQLException {

    int seq = 2;
    buffer.getLengthEncodedNumeric(); // field pos
    String fileName = buffer.readStringNullEnd(StandardCharsets.UTF_8);
    try {
      // Server request the local file (LOCAL DATA LOCAL INFILE)
      // We do accept general URLs, too. If the localInfileStream is
      // set, use that.
      InputStream is;
      writer.startPacket(seq);
      if (localInfileInputStream == null) {

        if (!getUrlParser().getOptions().allowLocalInfile) {
          writer.writeEmptyPacket();
          reader.getPacket(true);
          throw new SQLException(
              "Usage of LOCAL INFILE is disabled. To use it enable it via the connection property allowLocalInfile=true",
              FEATURE_NOT_SUPPORTED.getSqlState(),
              -1);
        }

        // validate all defined interceptors
        ServiceLoader<LocalInfileInterceptor> loader =
            ServiceLoader.load(LocalInfileInterceptor.class);
        for (LocalInfileInterceptor interceptor : loader) {
          if (!interceptor.validate(fileName)) {
            writer.writeEmptyPacket();
            reader.getPacket(true);
            throw new SQLException(
                "LOAD DATA LOCAL INFILE request to send local file named \""
                    + fileName
                    + "\" not validated by interceptor \""
                    + interceptor.getClass().getName()
                    + "\"");
          }
        }

        if (results.getSql() == null) {
          writer.writeEmptyPacket();
          reader.getPacket(true);
          throw new SQLException(
              "LOAD DATA LOCAL INFILE not permit in batch. file '" + fileName + "'",
              SqlStates.INVALID_AUTHORIZATION.getSqlState(),
              -1);

        } else if (!Utils.validateFileName(results.getSql(), results.getParameters(), fileName)) {
          writer.writeEmptyPacket();
          reader.getPacket(true);
          throw new SQLException(
              "LOAD DATA LOCAL INFILE asked for file '"
                  + fileName
                  + "' that doesn't correspond to initial query "
                  + results.getSql()
                  + ". Possible malicious proxy changing server answer ! Command interrupted",
              SqlStates.INVALID_AUTHORIZATION.getSqlState(),
              -1);
        }

        try {
          URL url = new URL(fileName);
          is = url.openStream();
        } catch (IOException ioe) {
          try {
            is = new FileInputStream(fileName);
          } catch (FileNotFoundException f) {
            writer.writeEmptyPacket();
            reader.getPacket(true);
            throw new SQLException("Could not send file : " + f.getMessage(), "22000", -1, f);
          }
        }
      } else {
        is = localInfileInputStream;
        localInfileInputStream = null;
      }

      try {

        byte[] buf = new byte[8192];
        int len;
        while ((len = is.read(buf)) > 0) {
          writer.startPacket(seq++);
          writer.write(buf, 0, len);
          writer.flush();
        }
        writer.writeEmptyPacket();

      } catch (IOException ioe) {
        throw handleIoException(ioe);
      } finally {
        is.close();
      }

      getResult(results);

    } catch (IOException e) {
      throw handleIoException(e);
    }
  }

  /**
   * Read ResultSet Packet.
   *
   * @param buffer current buffer
   * @param results result object
   * @throws SQLException if sub-result connection fail
   * @see <a href="https://mariadb.com/kb/en/mariadb/resultset/">resultSet packets</a>
   */
  private void readResultSet(Buffer buffer, Results results) throws SQLException {
    long fieldCount = buffer.getLengthEncodedNumeric();

    if (fieldCount < 0 || fieldCount > options.maxAllowedColumns) {
      throw new SQLException(
          String.format(
              "Server metadata announces %d columns, exceeding the maximum allowed number of columns"
                  + " (%d) permitted by the 'maxAllowedColumns' option. This may indicate a malicious"
                  + " proxy attempting to exhaust client memory. Command interrupted.",
              fieldCount, options.maxAllowedColumns),
          "HY000");
    }

    try {

      // read columns information's
      ColumnDefinition[] ci = new ColumnDefinition[(int) fieldCount];
      for (int i = 0; i < fieldCount; i++) {
        ci[i] = new ColumnDefinition(reader.getPacket(false));
      }

      boolean callableResult = false;
      if (!eofDeprecated) {
        // read EOF packet
        // EOF status is mandatory because :
        // - Call query will have an callable resultSet for OUT parameters
        //   -> this resultSet must be identified and not listed in JDBC statement.getResultSet()
        // - after a callable resultSet, a OK packet is send, but mysql does send the  a bad "more
        // result flag"
        Buffer bufferEof = reader.getPacket(true);
        if (bufferEof.readByte() != EOF) {
          // using IOException to close connection,
          throw new IOException(
              "Packets out of order when reading field packets, expected was EOF stream."
                  + ((options.enablePacketDebug)
                      ? getTraces()
                      : "Packet contents (hex) = "
                          + Utils.hexdump(
                              options.maxQuerySizeToLog, 0, bufferEof.limit, bufferEof.buf)));
        }
        bufferEof.skipBytes(2); // Skip warningCount
        callableResult = (bufferEof.readShort() & ServerStatus.PS_OUT_PARAMETERS) != 0;
      }

      // read resultSet
      SelectResultSet selectResultSet;
      if (results.getResultSetConcurrency() == ResultSet.CONCUR_READ_ONLY) {
        selectResultSet =
            new SelectResultSet(ci, results, this, reader, callableResult, eofDeprecated);
      } else {
        // remove fetch size to permit updating results without creating new connection
        results.removeFetchSize();
        selectResultSet =
            new UpdatableResultSet(ci, results, this, reader, callableResult, eofDeprecated);
      }

      results.addResultSet(selectResultSet, hasMoreResults() || results.getFetchSize() > 0);

    } catch (IOException e) {
      throw handleIoException(e);
    }
  }

  public void prologProxy(
      ServerPrepareResult serverPrepareResult,
      long maxRows,
      boolean hasProxy,
      MariaDbConnection connection,
      MariaDbStatement statement)
      throws SQLException {
    prolog(maxRows, hasProxy, connection, statement);
  }

  /**
   * Preparation before command.
   *
   * @param maxRows query max rows
   * @param hasProxy has proxy
   * @param connection current connection
   * @param statement current statement
   * @throws SQLException if any error occur.
   */
  public void prolog(
      long maxRows, boolean hasProxy, MariaDbConnection connection, MariaDbStatement statement)
      throws SQLException {
    if (explicitClosed) {
      throw new SQLNonTransientConnectionException(
          "execute() is called on closed connection", "08000");
    }
    // old failover handling
    if (!hasProxy && shouldReconnectWithoutProxy()) {
      try {
        connectWithoutProxy();
      } catch (SQLException qe) {
        throw ExceptionFactory.of((int) serverThreadId, options).create(qe);
      }
    }

    try {
      setMaxRows(maxRows);
    } catch (SQLException qe) {
      throw ExceptionFactory.of((int) serverThreadId, options).create(qe);
    }

    connection.reenableWarnings();
  }

  public ServerPrepareResult putInCache(String key, ServerPrepareResult serverPrepareResult) {
    return serverPrepareStatementCache.put(key, serverPrepareResult);
  }

  private void cmdPrologue() throws SQLException {

    // load active result if any so buffer are clean for next query
    if (activeStreamingResult != null) {
      activeStreamingResult.loadFully(false, this);
      activeStreamingResult = null;
    }

    if (activeFutureTask != null) {
      // wait for remaining batch result to be read, to ensure correct connection state
      try {
        activeFutureTask.get();
      } catch (ExecutionException executionException) {
        // last batch exception are to be discarded
      } catch (InterruptedException interruptedException) {
        Thread.currentThread().interrupt();
        throw new SQLException(
            "Interrupted reading remaining batch response ",
            INTERRUPTED_EXCEPTION.getSqlState(),
            -1,
            interruptedException);
      } finally {
        // bulk can prepare, and so if prepare cache is enable, can replace an already cached
        // prepareStatement
        // this permit to release those old prepared statement without conflict.
        forceReleaseWaitingPrepareStatement();
      }
      activeFutureTask = null;
    }

    if (!this.connected) {
      throw exceptionFactory.create("Connection is closed", "08000", 1220);
    }
    interrupted = false;
    if (this.options.ensureSocketState) {
      // ensure that the socket buffer is empty before issuing new command.
      // (this doesn't concern pipelining commands).
      // If data is present in socket, an error will be raised, throwing the content of socket data
      // to permit
      // identification of error.
      try {
        int avail = this.reader.getInputStream().available();
        if (avail > 0) {
          // unexpected data in socket buffer

          // reading socket buffer to add content to error.
          byte[] data = new byte[Math.min(avail, 16000)];
          int remaining = avail;
          int off = 0;
          do {
            int count = this.reader.getInputStream().read(data, off, remaining);
            if (count < 0) {
              break;
            }
            remaining -= count;
            off += count;
          } while (remaining > 0);

          throw exceptionFactory.create(
              "Unexpected data in socket buffer:" + Utils.hexdump(data), "HY000");
        }

      } catch (IOException ioe) {
        throw exceptionFactory.create("Unexpected socket error", "08000", ioe);
      }
    }
  }

  /**
   * Set current state after a failover.
   *
   * @param maxRows current Max rows
   * @param transactionIsolationLevel current transactionIsolationLevel
   * @param database current database
   * @param autocommit current autocommit state
   * @throws SQLException if any error occur.
   */
  // TODO set all client affected variables when implementing CONJ-319
  public void resetStateAfterFailover(
      long maxRows, int transactionIsolationLevel, String database, boolean autocommit)
      throws SQLException {
    setMaxRows(maxRows);

    if (transactionIsolationLevel != 0) {
      setTransactionIsolation(transactionIsolationLevel);
    }

    if (database != null && !"".equals(database) && !getDatabase().equals(database)) {
      setCatalog(database);
    }

    if (getAutocommit() != autocommit) {
      executeQuery("set autocommit=" + (autocommit ? "1" : "0"));
    }
  }

  /**
   * Handle IoException (reconnect if Exception is due to having send too much data, making server
   * close the connection.
   *
   * <p>There is 3 kind of IOException :
   *
   * <ol>
   *   <li>MaxAllowedPacketException : without need of reconnect : thrown when driver don't send
   *       packet that would have been too big then error is not a CONNECTION_EXCEPTION
   *   <li>packets size is greater than max_allowed_packet (can be checked with
   *       writer.isAllowedCmdLength()). Need to reconnect
   *   <li>unknown IO error throw a CONNECTION_EXCEPTION
   * </ol>
   *
   * @param initialException initial Io error
   * @return the resulting error to return to client.
   */
  public SQLException handleIoException(Exception initialException) {
    boolean mustReconnect = options.autoReconnect;
    boolean maxSizeError;

    if (initialException instanceof MaxAllowedPacketException) {
      maxSizeError = true;
      if (((MaxAllowedPacketException) initialException).isMustReconnect()) {
        mustReconnect = true;
      } else {
        return new SQLNonTransientConnectionException(
            initialException.getMessage() + getTraces(),
            UNDEFINED_SQLSTATE.getSqlState(),
            initialException);
      }
    } else if (initialException instanceof NotSerializableException) {
      return new SerialException(
          "Parameter cannot be serialized: " + initialException.getMessage());
    } else {
      maxSizeError = writer.exceedMaxLength();
      if (maxSizeError) {
        mustReconnect = true;
      }
      if (initialException instanceof SocketTimeoutException) destroySocket();
    }

    if (mustReconnect && !explicitClosed) {
      String traces = getTraces();
      try {
        connect();
        try {
          resetStateAfterFailover(
              getMaxRows(), getTransactionIsolationLevel(), getDatabase(), getAutocommit());

          if (maxSizeError) {
            return new SQLTransientConnectionException(
                "Could not send query: query size is >= to max_allowed_packet ("
                    + writer.getMaxAllowedPacket()
                    + ")"
                    + traces,
                "HY000",
                initialException);
          }
          if (initialException instanceof SocketTimeoutException) {
            return new SqlSocketTimeoutException(
                initialException.getMessage() + traces, "HY000", initialException);
          }

          return new SQLTransientConnectionException(
              initialException.getMessage() + traces, "HY000", initialException);

        } catch (SQLException queryException) {
          return new SQLTransientConnectionException(
              "reconnection succeed, but resetting previous state failed" + traces,
              "HY000",
              initialException);
        }

      } catch (SQLException queryException) {
        connected = false;
        return new SQLNonTransientConnectionException(
            initialException.getMessage() + "\nError during reconnection" + traces,
            "08000",
            queryException);
      }
    }
    connected = false;
    if (initialException instanceof SocketTimeoutException) {
      return new SqlSocketTimeoutException(
          initialException.getMessage() + getTraces(), "08000", initialException);
    }

    return new SQLNonTransientConnectionException(
        initialException.getMessage() + getTraces(), "08000", initialException);
  }

  public void setActiveFutureTask(FutureTask activeFutureTask) {
    this.activeFutureTask = activeFutureTask;
  }

  public void interrupt() {
    interrupted = true;
  }

  public boolean isInterrupted() {
    return interrupted;
  }

  /**
   * Throw TimeoutException if timeout has been reached.
   *
   * @throws SQLTimeoutException to indicate timeout exception.
   */
  public void stopIfInterrupted() throws SQLTimeoutException {
    if (isInterrupted()) {
      // interrupted during read, must throw an exception manually
      throw new SQLTimeoutException("Timeout during batch execution");
    }
  }
}
