/**
 * 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
 * with 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 org.apache.hadoop.hive.ql;

import java.io.ByteArrayOutputStream;
import java.io.DataInput;
import java.io.IOException;
import java.io.PrintStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;

import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.hive.common.ValidTxnList;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.conf.HiveConf.ConfVars;
import org.apache.hadoop.hive.conf.HiveVariableSource;
import org.apache.hadoop.hive.conf.VariableSubstitution;
import org.apache.hadoop.hive.metastore.MetaStoreUtils;
import org.apache.hadoop.hive.metastore.api.FieldSchema;
import org.apache.hadoop.hive.metastore.api.Schema;
import org.apache.hadoop.hive.ql.exec.ConditionalTask;
import org.apache.hadoop.hive.ql.exec.ExplainTask;
import org.apache.hadoop.hive.ql.exec.FetchTask;
import org.apache.hadoop.hive.ql.exec.TableScanOperator;
import org.apache.hadoop.hive.ql.exec.Task;
import org.apache.hadoop.hive.ql.exec.TaskFactory;
import org.apache.hadoop.hive.ql.exec.TaskResult;
import org.apache.hadoop.hive.ql.exec.TaskRunner;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.history.HiveHistory.Keys;
import org.apache.hadoop.hive.ql.hooks.Entity;
import org.apache.hadoop.hive.ql.hooks.ExecuteWithHookContext;
import org.apache.hadoop.hive.ql.hooks.Hook;
import org.apache.hadoop.hive.ql.hooks.HookContext;
import org.apache.hadoop.hive.ql.hooks.HookUtils;
import org.apache.hadoop.hive.ql.hooks.PostExecute;
import org.apache.hadoop.hive.ql.hooks.PreExecute;
import org.apache.hadoop.hive.ql.hooks.ReadEntity;
import org.apache.hadoop.hive.ql.hooks.WriteEntity;
import org.apache.hadoop.hive.ql.lockmgr.HiveLock;
import org.apache.hadoop.hive.ql.lockmgr.HiveTxnManager;
import org.apache.hadoop.hive.ql.lockmgr.LockException;
import org.apache.hadoop.hive.ql.log.PerfLogger;
import org.apache.hadoop.hive.ql.metadata.AuthorizationException;
import org.apache.hadoop.hive.ql.metadata.Hive;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.metadata.Table;
import org.apache.hadoop.hive.ql.metadata.formatting.JsonMetaDataFormatter;
import org.apache.hadoop.hive.ql.metadata.formatting.MetaDataFormatUtils;
import org.apache.hadoop.hive.ql.metadata.formatting.MetaDataFormatter;
import org.apache.hadoop.hive.ql.optimizer.ppr.PartitionPruner;
import org.apache.hadoop.hive.ql.parse.ASTNode;
import org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer;
import org.apache.hadoop.hive.ql.parse.ColumnAccessInfo;
import org.apache.hadoop.hive.ql.parse.HiveSemanticAnalyzerHook;
import org.apache.hadoop.hive.ql.parse.HiveSemanticAnalyzerHookContext;
import org.apache.hadoop.hive.ql.parse.HiveSemanticAnalyzerHookContextImpl;
import org.apache.hadoop.hive.ql.parse.ImportSemanticAnalyzer;
import org.apache.hadoop.hive.ql.parse.ParseContext;
import org.apache.hadoop.hive.ql.parse.ParseDriver;
import org.apache.hadoop.hive.ql.parse.ParseUtils;
import org.apache.hadoop.hive.ql.parse.PrunedPartitionList;
import org.apache.hadoop.hive.ql.parse.SemanticAnalyzer;
import org.apache.hadoop.hive.ql.parse.SemanticAnalyzerFactory;
import org.apache.hadoop.hive.ql.plan.FileSinkDesc;
import org.apache.hadoop.hive.ql.plan.HiveOperation;
import org.apache.hadoop.hive.ql.plan.TableDesc;
import org.apache.hadoop.hive.ql.processors.CommandProcessor;
import org.apache.hadoop.hive.ql.processors.CommandProcessorResponse;
import org.apache.hadoop.hive.ql.security.authorization.AuthorizationUtils;
import org.apache.hadoop.hive.ql.security.authorization.HiveAuthorizationProvider;
import org.apache.hadoop.hive.ql.security.authorization.plugin.HiveOperationType;
import org.apache.hadoop.hive.ql.security.authorization.plugin.HivePrivilegeObject;
import org.apache.hadoop.hive.ql.security.authorization.plugin.HivePrivilegeObject.HivePrivObjectActionType;
import org.apache.hadoop.hive.ql.security.authorization.plugin.HivePrivilegeObject.HivePrivilegeObjectType;
import org.apache.hadoop.hive.ql.security.authorization.plugin.HiveAuthzContext;
import org.apache.hadoop.hive.ql.session.OperationLog;
import org.apache.hadoop.hive.ql.session.OperationLog.LoggingLevel;
import org.apache.hadoop.hive.ql.session.SessionState;
import org.apache.hadoop.hive.ql.session.SessionState.LogHelper;
import org.apache.hadoop.hive.serde2.ByteStream;
import org.apache.hadoop.hive.serde2.thrift.ThriftJDBCBinarySerDe;
import org.apache.hadoop.hive.shims.Utils;
import org.apache.hadoop.mapred.ClusterStatus;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hive.common.util.ShutdownHookManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;

public class Driver implements CommandProcessor {

  static final private String CLASS_NAME = Driver.class.getName();
  private static final Logger LOG = LoggerFactory.getLogger(CLASS_NAME);
  static final private LogHelper console = new LogHelper(LOG);
  static final int SHUTDOWN_HOOK_PRIORITY = 0;
  private Runnable shutdownRunner = null;

  private int maxRows = 100;
  ByteStream.Output bos = new ByteStream.Output();

  private final HiveConf conf;
  private final boolean isParallelEnabled;
  private DataInput resStream;
  private Context ctx;
  private DriverContext driverCxt;
  private QueryPlan plan;
  private Schema schema;
  private String errorMessage;
  private String SQLState;
  private Throwable downstreamError;

  private FetchTask fetchTask;
  List<HiveLock> hiveLocks = new ArrayList<HiveLock>();

  // A list of FileSinkOperators writing in an ACID compliant manner
  private Set<FileSinkDesc> acidSinks;
  // whether any ACID table is involved in a query
  private boolean acidInQuery;

  // A limit on the number of threads that can be launched
  private int maxthreads;
  private int tryCount = Integer.MAX_VALUE;

  private boolean destroyed;

  private String userName;

  // HS2 operation handle guid string
  private String operationId;

  // For WebUI.  Kept alive after queryPlan is freed.
  private final QueryDisplay queryDisplay = new QueryDisplay();

  // Query specific info
  private QueryState queryState;

  private boolean checkConcurrency() {
    boolean supportConcurrency = conf.getBoolVar(HiveConf.ConfVars.HIVE_SUPPORT_CONCURRENCY);
    if (!supportConcurrency) {
      LOG.info("Concurrency mode is disabled, not creating a lock manager");
      return false;
    }
    return true;
  }

  @Override
  public void init() {
    // Nothing for now.
  }

  /**
   * Return the status information about the Map-Reduce cluster
   */
  public ClusterStatus getClusterStatus() throws Exception {
    ClusterStatus cs;
    try {
      JobConf job = new JobConf(conf);
      JobClient jc = new JobClient(job);
      cs = jc.getClusterStatus();
    } catch (Exception e) {
      e.printStackTrace();
      throw e;
    }
    LOG.info("Returning cluster status: " + cs.toString());
    return cs;
  }


  public Schema getSchema() {
    return schema;
  }

  /**
   * Get a Schema with fields represented with native Hive types
   */
  private static Schema getSchema(BaseSemanticAnalyzer sem, HiveConf conf) {
    Schema schema = null;

    // If we have a plan, prefer its logical result schema if it's
    // available; otherwise, try digging out a fetch task; failing that,
    // give up.
    if (sem == null) {
      // can't get any info without a plan
    } else if (sem.getResultSchema() != null) {
      List<FieldSchema> lst = sem.getResultSchema();
      schema = new Schema(lst, null);
    } else if (sem.getFetchTask() != null) {
      FetchTask ft = sem.getFetchTask();
      TableDesc td = ft.getTblDesc();
      // partitioned tables don't have tableDesc set on the FetchTask. Instead
      // they have a list of PartitionDesc objects, each with a table desc.
      // Let's
      // try to fetch the desc for the first partition and use it's
      // deserializer.
      if (td == null && ft.getWork() != null && ft.getWork().getPartDesc() != null) {
        if (ft.getWork().getPartDesc().size() > 0) {
          td = ft.getWork().getPartDesc().get(0).getTableDesc();
        }
      }

      if (td == null) {
        LOG.info("No returning schema.");
      } else {
        String tableName = "result";
        List<FieldSchema> lst = null;
        try {
          lst = MetaStoreUtils.getFieldsFromDeserializer(tableName, td.getDeserializer(conf));
        } catch (Exception e) {
          LOG.warn("Error getting schema: "
              + org.apache.hadoop.util.StringUtils.stringifyException(e));
        }
        if (lst != null) {
          schema = new Schema(lst, null);
        }
      }
    }
    if (schema == null) {
      schema = new Schema();
    }
    LOG.info("Returning Hive schema: " + schema);
    return schema;
  }

  /**
   * Get a Schema with fields represented with Thrift DDL types
   */
  public Schema getThriftSchema() throws Exception {
    Schema schema;
    try {
      schema = getSchema();
      if (schema != null) {
        List<FieldSchema> lst = schema.getFieldSchemas();
        // Go over the schema and convert type to thrift type
        if (lst != null) {
          for (FieldSchema f : lst) {
            f.setType(MetaStoreUtils.typeToThriftType(f.getType()));
          }
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
      throw e;
    }
    LOG.info("Returning Thrift schema: " + schema);
    return schema;
  }

  /**
   * Return the maximum number of rows returned by getResults
   */
  public int getMaxRows() {
    return maxRows;
  }

  /**
   * Set the maximum number of rows returned by getResults
   */
  public void setMaxRows(int maxRows) {
    this.maxRows = maxRows;
  }

  public Driver() {
    this(new QueryState((SessionState.get() != null) ?
        SessionState.get().getConf() : new HiveConf()), null);
  }

  public Driver(HiveConf conf) {
    this(new QueryState(conf), null);
  }

  public Driver(HiveConf conf, String userName) {
    this(new QueryState(conf), userName);
  }

  public Driver(QueryState queryState, String userName) {
    this.queryState = queryState;
    this.conf = queryState.getConf();
    isParallelEnabled = (conf != null)
        && HiveConf.getBoolVar(conf, ConfVars.HIVE_SERVER2_PARALLEL_COMPILATION);
    this.userName = userName;
  }

  /**
   * Compile a new query. Any currently-planned query associated with this Driver is discarded.
   * Do not reset id for inner queries(index, etc). Task ids are used for task identity check.
   *
   * @param command
   *          The SQL query to compile.
   */
  public int compile(String command) {
    return compile(command, true);
  }

  /**
   * Compile a new query, but potentially reset taskID counter.  Not resetting task counter
   * is useful for generating re-entrant QL queries.
   * @param command  The HiveQL query to compile
   * @param resetTaskIds Resets taskID counter if true.
   * @return 0 for ok
   */
  public int compile(String command, boolean resetTaskIds) {
    PerfLogger perfLogger = SessionState.getPerfLogger(true);
    perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.DRIVER_RUN);
    perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.COMPILE);

    command = new VariableSubstitution(new HiveVariableSource() {
      @Override
      public Map<String, String> getHiveVariable() {
        return SessionState.get().getHiveVariables();
      }
    }).substitute(conf, command);

    String queryStr = command;

    try {
      // command should be redacted to avoid to logging sensitive data
      queryStr = HookUtils.redactLogString(conf, command);
    } catch (Exception e) {
      LOG.warn("WARNING! Query command could not be redacted." + e);
    }

    if (ctx != null) {
      close();
    }

    if (resetTaskIds) {
      TaskFactory.resetId();
    }

    String queryId = conf.getVar(HiveConf.ConfVars.HIVEQUERYID);

    //save some info for webUI for use after plan is freed
    this.queryDisplay.setQueryStr(queryStr);
    this.queryDisplay.setQueryId(queryId);

    LOG.info("Compiling command(queryId=" + queryId + "): " + queryStr);

    SessionState.get().setupQueryCurrentTimestamp();

    try {
      // Initialize the transaction manager.  This must be done before analyze is called.
      final HiveTxnManager txnManager = SessionState.get().initTxnMgr(conf);
      // In case when user Ctrl-C twice to kill Hive CLI JVM, we want to release locks

      // if compile is being called multiple times, clear the old shutdownhook
      ShutdownHookManager.removeShutdownHook(shutdownRunner);
      shutdownRunner = new Runnable() {
        @Override
        public void run() {
          try {
            releaseLocksAndCommitOrRollback(false, txnManager);
          } catch (LockException e) {
            LOG.warn("Exception when releasing locks in ShutdownHook for Driver: " +
                e.getMessage());
          }
        }
      };
      ShutdownHookManager.addShutdownHook(shutdownRunner, SHUTDOWN_HOOK_PRIORITY);

      ctx = new Context(conf);
      ctx.setTryCount(getTryCount());
      ctx.setCmd(command);
      ctx.setHDFSCleanup(true);

      perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.PARSE);
      ParseDriver pd = new ParseDriver();
      ASTNode tree = pd.parse(command, ctx);
      tree = ParseUtils.findRootNonNullToken(tree);
      perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.PARSE);


      perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.ANALYZE);
      BaseSemanticAnalyzer sem = SemanticAnalyzerFactory.get(queryState, tree);
      List<HiveSemanticAnalyzerHook> saHooks =
          getHooks(HiveConf.ConfVars.SEMANTIC_ANALYZER_HOOK,
              HiveSemanticAnalyzerHook.class);

      // Flush the metastore cache.  This assures that we don't pick up objects from a previous
      // query running in this same thread.  This has to be done after we get our semantic
      // analyzer (this is when the connection to the metastore is made) but before we analyze,
      // because at that point we need access to the objects.
      Hive.get().getMSC().flushCache();

      // Do semantic analysis and plan generation
      if (saHooks != null && !saHooks.isEmpty()) {
        HiveSemanticAnalyzerHookContext hookCtx = new HiveSemanticAnalyzerHookContextImpl();
        hookCtx.setConf(conf);
        hookCtx.setUserName(userName);
        hookCtx.setIpAddress(SessionState.get().getUserIpAddress());
        hookCtx.setCommand(command);
        for (HiveSemanticAnalyzerHook hook : saHooks) {
          tree = hook.preAnalyze(hookCtx, tree);
        }
        sem.analyze(tree, ctx);
        hookCtx.update(sem);
        for (HiveSemanticAnalyzerHook hook : saHooks) {
          hook.postAnalyze(hookCtx, sem.getAllRootTasks());
        }
      } else {
        sem.analyze(tree, ctx);
      }
      // Record any ACID compliant FileSinkOperators we saw so we can add our transaction ID to
      // them later.
      acidSinks = sem.getAcidFileSinks();

      LOG.info("Semantic Analysis Completed");

      // validate the plan
      sem.validate();
      acidInQuery = sem.hasAcidInQuery();
      perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.ANALYZE);

      // get the output schema
      schema = getSchema(sem, conf);

      plan = new QueryPlan(queryStr, sem, perfLogger.getStartTime(PerfLogger.DRIVER_RUN), queryId,
        queryState.getHiveOperation(), schema);

      conf.setQueryString(queryStr);

      conf.set("mapreduce.workflow.id", "hive_" + queryId);
      conf.set("mapreduce.workflow.name", queryStr);

      // initialize FetchTask right here
      if (plan.getFetchTask() != null) {
        plan.getFetchTask().initialize(queryState, plan, null, ctx.getOpContext());
      }

      //do the authorization check
      if (!sem.skipAuthorization() &&
          HiveConf.getBoolVar(conf, HiveConf.ConfVars.HIVE_AUTHORIZATION_ENABLED)) {

        try {
          perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.DO_AUTHORIZATION);
          doAuthorization(queryState.getHiveOperation(), sem, command);
        } catch (AuthorizationException authExp) {
          console.printError("Authorization failed:" + authExp.getMessage()
              + ". Use SHOW GRANT to get more details.");
          errorMessage = authExp.getMessage();
          SQLState = "42000";
          return 403;
        } finally {
          perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.DO_AUTHORIZATION);
        }
      }

      if (conf.getBoolVar(ConfVars.HIVE_LOG_EXPLAIN_OUTPUT)) {
        String explainOutput = getExplainOutput(sem, plan, tree);
        if (explainOutput != null) {
          if (conf.getBoolVar(ConfVars.HIVE_LOG_EXPLAIN_OUTPUT)) {
            LOG.info("EXPLAIN output for queryid " + queryId + " : "
              + explainOutput);
          }
          if (conf.isWebUiQueryInfoCacheEnabled()) {
            queryDisplay.setExplainPlan(explainOutput);
          }
        }
      }
      return 0;
    } catch (Exception e) {
      ErrorMsg error = ErrorMsg.getErrorMsg(e.getMessage());
      errorMessage = "FAILED: " + e.getClass().getSimpleName();
      if (error != ErrorMsg.GENERIC_ERROR) {
        errorMessage += " [Error "  + error.getErrorCode()  + "]:";
      }

      // HIVE-4889
      if ((e instanceof IllegalArgumentException) && e.getMessage() == null && e.getCause() != null) {
        errorMessage += " " + e.getCause().getMessage();
      } else {
        errorMessage += " " + e.getMessage();
      }

      if (error == ErrorMsg.TXNMGR_NOT_ACID) {
        errorMessage += ". Failed command: " + queryStr;
      }

      SQLState = error.getSQLState();
      downstreamError = e;
      console.printError(errorMessage, "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return error.getErrorCode();//todo: this is bad if returned as cmd shell exit
      // since it exceeds valid range of shell return values
    } finally {
      double duration = perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.COMPILE)/1000.00;
      ImmutableMap<String, Long> compileHMSTimings = dumpMetaCallTimingWithoutEx("compilation");
      queryDisplay.setHmsTimings(QueryDisplay.Phase.COMPILATION, compileHMSTimings);
      LOG.info("Completed compiling command(queryId=" + queryId + "); Time taken: " + duration + " seconds");
    }
  }

  private ImmutableMap<String, Long> dumpMetaCallTimingWithoutEx(String phase) {
    try {
      return Hive.get().dumpAndClearMetaCallTiming(phase);
    } catch (HiveException he) {
      LOG.warn("Caught exception attempting to write metadata call information " + he, he);
    }
    return null;
  }

  /**
   * Returns EXPLAIN EXTENDED output for a semantically
   * analyzed query.
   *
   * @param sem semantic analyzer for analyzed query
   * @param plan query plan
   * @param astTree AST tree dump
   * @throws java.io.IOException
   */
  private String getExplainOutput(BaseSemanticAnalyzer sem, QueryPlan plan,
      ASTNode astTree) throws IOException {
    String ret = null;
    ExplainTask task = new ExplainTask();
    task.initialize(queryState, plan, null, ctx.getOpContext());
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    PrintStream ps = new PrintStream(baos);
    try {
      List<Task<?>> rootTasks = sem.getAllRootTasks();
      task.getJSONPlan(ps, rootTasks, sem.getFetchTask(), false, true, true);
      ret = baos.toString();
    } catch (Exception e) {
      LOG.warn("Exception generating explain output: " + e, e);
    }

    return ret;
  }

  /**
   * Do authorization using post semantic analysis information in the semantic analyzer
   * The original command is also passed so that authorization interface can provide
   * more useful information in logs.
   * @param sem SemanticAnalyzer used to parse input query
   * @param command input query
   * @throws HiveException
   * @throws AuthorizationException
   */
  public static void doAuthorization(HiveOperation op, BaseSemanticAnalyzer sem, String command)
      throws HiveException, AuthorizationException {
    SessionState ss = SessionState.get();
    Hive db = sem.getDb();

    Set<ReadEntity> additionalInputs = new HashSet<ReadEntity>();
    for (Entity e : sem.getInputs()) {
      if (e.getType() == Entity.Type.PARTITION) {
        additionalInputs.add(new ReadEntity(e.getTable()));
      }
    }

    Set<WriteEntity> additionalOutputs = new HashSet<WriteEntity>();
    for (WriteEntity e : sem.getOutputs()) {
      if (e.getType() == Entity.Type.PARTITION) {
        additionalOutputs.add(new WriteEntity(e.getTable(), e.getWriteType()));
      }
    }

    // The following union operation returns a union, which traverses over the
    // first set once and then  then over each element of second set, in order, 
    // that is not contained in first. This means it doesn't replace anything
    // in first set, and would preserve the WriteType in WriteEntity in first
    // set in case of outputs list.
    Set<ReadEntity> inputs = Sets.union(sem.getInputs(), additionalInputs);
    Set<WriteEntity> outputs = Sets.union(sem.getOutputs(), additionalOutputs);

    if (ss.isAuthorizationModeV2()) {
      // get mapping of tables to columns used
      ColumnAccessInfo colAccessInfo = sem.getColumnAccessInfo();
      // colAccessInfo is set only in case of SemanticAnalyzer
      Map<String, List<String>> selectTab2Cols = colAccessInfo != null ? colAccessInfo
          .getTableToColumnAccessMap() : null;
      Map<String, List<String>> updateTab2Cols = sem.getUpdateColumnAccessInfo() != null ?
          sem.getUpdateColumnAccessInfo().getTableToColumnAccessMap() : null;
      doAuthorizationV2(ss, op, inputs, outputs, command, selectTab2Cols, updateTab2Cols);
     return;
    }
    if (op == null) {
      throw new HiveException("Operation should not be null");
    }
    HiveAuthorizationProvider authorizer = ss.getAuthorizer();
    if (op.equals(HiveOperation.CREATEDATABASE)) {
      authorizer.authorize(
          op.getInputRequiredPrivileges(), op.getOutputRequiredPrivileges());
    } else if (op.equals(HiveOperation.CREATETABLE_AS_SELECT)
        || op.equals(HiveOperation.CREATETABLE)) {
      authorizer.authorize(
          db.getDatabase(SessionState.get().getCurrentDatabase()), null,
          HiveOperation.CREATETABLE_AS_SELECT.getOutputRequiredPrivileges());
    } else {
      if (op.equals(HiveOperation.IMPORT)) {
        ImportSemanticAnalyzer isa = (ImportSemanticAnalyzer) sem;
        if (!isa.existsTable()) {
          authorizer.authorize(
              db.getDatabase(SessionState.get().getCurrentDatabase()), null,
              HiveOperation.CREATETABLE_AS_SELECT.getOutputRequiredPrivileges());
        }
      }
    }
    if (outputs != null && outputs.size() > 0) {
      for (WriteEntity write : outputs) {
        if (write.isDummy() || write.isPathType()) {
          continue;
        }
        if (write.getType() == Entity.Type.DATABASE) {
          if (!op.equals(HiveOperation.IMPORT)){
            // We skip DB check for import here because we already handle it above
            // as a CTAS check.
            authorizer.authorize(write.getDatabase(),
                null, op.getOutputRequiredPrivileges());
          }
          continue;
        }

        if (write.getType() == WriteEntity.Type.PARTITION) {
          Partition part = db.getPartition(write.getTable(), write
              .getPartition().getSpec(), false);
          if (part != null) {
            authorizer.authorize(write.getPartition(), null,
                    op.getOutputRequiredPrivileges());
            continue;
          }
        }

        if (write.getTable() != null) {
          authorizer.authorize(write.getTable(), null,
                  op.getOutputRequiredPrivileges());
        }
      }
    }

    if (inputs != null && inputs.size() > 0) {
      Map<Table, List<String>> tab2Cols = new HashMap<Table, List<String>>();
      Map<Partition, List<String>> part2Cols = new HashMap<Partition, List<String>>();

      //determine if partition level privileges should be checked for input tables
      Map<String, Boolean> tableUsePartLevelAuth = new HashMap<String, Boolean>();
      for (ReadEntity read : inputs) {
        if (read.isDummy() || read.isPathType() || read.getType() == Entity.Type.DATABASE) {
          continue;
        }
        Table tbl = read.getTable();
        if ((read.getPartition() != null) || (tbl != null && tbl.isPartitioned())) {
          String tblName = tbl.getTableName();
          if (tableUsePartLevelAuth.get(tblName) == null) {
            boolean usePartLevelPriv = (tbl.getParameters().get(
                "PARTITION_LEVEL_PRIVILEGE") != null && ("TRUE"
                .equalsIgnoreCase(tbl.getParameters().get(
                    "PARTITION_LEVEL_PRIVILEGE"))));
            if (usePartLevelPriv) {
              tableUsePartLevelAuth.put(tblName, Boolean.TRUE);
            } else {
              tableUsePartLevelAuth.put(tblName, Boolean.FALSE);
            }
          }
        }
      }

      // column authorization is checked through table scan operators.
      getTablePartitionUsedColumns(op, sem, tab2Cols, part2Cols, tableUsePartLevelAuth);

      // cache the results for table authorization
      Set<String> tableAuthChecked = new HashSet<String>();
      for (ReadEntity read : inputs) {
        // if read is not direct, we do not need to check its autho.
        if (read.isDummy() || read.isPathType() || !read.isDirect()) {
          continue;
        }
        if (read.getType() == Entity.Type.DATABASE) {
          authorizer.authorize(read.getDatabase(), op.getInputRequiredPrivileges(), null);
          continue;
        }
        Table tbl = read.getTable();
        if (tbl.isView() && sem instanceof SemanticAnalyzer) {
          tab2Cols.put(tbl,
              sem.getColumnAccessInfo().getTableToColumnAccessMap().get(tbl.getCompleteName()));
        }
        if (read.getPartition() != null) {
          Partition partition = read.getPartition();
          tbl = partition.getTable();
          // use partition level authorization
          if (Boolean.TRUE.equals(tableUsePartLevelAuth.get(tbl.getTableName()))) {
            List<String> cols = part2Cols.get(partition);
            if (cols != null && cols.size() > 0) {
              authorizer.authorize(partition.getTable(),
                  partition, cols, op.getInputRequiredPrivileges(),
                  null);
            } else {
              authorizer.authorize(partition,
                  op.getInputRequiredPrivileges(), null);
            }
            continue;
          }
        }

        // if we reach here, it means it needs to do a table authorization
        // check, and the table authorization may already happened because of other
        // partitions
        if (tbl != null && !tableAuthChecked.contains(tbl.getTableName()) &&
            !(Boolean.TRUE.equals(tableUsePartLevelAuth.get(tbl.getTableName())))) {
          List<String> cols = tab2Cols.get(tbl);
          if (cols != null && cols.size() > 0) {
            authorizer.authorize(tbl, null, cols,
                op.getInputRequiredPrivileges(), null);
          } else {
            authorizer.authorize(tbl, op.getInputRequiredPrivileges(),
                null);
          }
          tableAuthChecked.add(tbl.getTableName());
        }
      }

    }
  }

  private static void getTablePartitionUsedColumns(HiveOperation op, BaseSemanticAnalyzer sem,
      Map<Table, List<String>> tab2Cols, Map<Partition, List<String>> part2Cols,
      Map<String, Boolean> tableUsePartLevelAuth) throws HiveException {
    // for a select or create-as-select query, populate the partition to column
    // (par2Cols) or
    // table to columns mapping (tab2Cols)
    if (op.equals(HiveOperation.CREATETABLE_AS_SELECT) || op.equals(HiveOperation.QUERY)) {
      SemanticAnalyzer querySem = (SemanticAnalyzer) sem;
      ParseContext parseCtx = querySem.getParseContext();

      for (Map.Entry<String, TableScanOperator> topOpMap : querySem.getParseContext().getTopOps()
          .entrySet()) {
        TableScanOperator tableScanOp = topOpMap.getValue();
        if (!tableScanOp.isInsideView()) {
          Table tbl = tableScanOp.getConf().getTableMetadata();
          List<Integer> neededColumnIds = tableScanOp.getNeededColumnIDs();
          List<FieldSchema> columns = tbl.getCols();
          List<String> cols = new ArrayList<String>();
          for (int i = 0; i < neededColumnIds.size(); i++) {
            cols.add(columns.get(neededColumnIds.get(i)).getName());
          }
          // map may not contain all sources, since input list may have been
          // optimized out
          // or non-existent tho such sources may still be referenced by the
          // TableScanOperator
          // if it's null then the partition probably doesn't exist so let's use
          // table permission
          if (tbl.isPartitioned()
              && Boolean.TRUE.equals(tableUsePartLevelAuth.get(tbl.getTableName()))) {
            String alias_id = topOpMap.getKey();

            PrunedPartitionList partsList = PartitionPruner.prune(tableScanOp, parseCtx, alias_id);
            Set<Partition> parts = partsList.getPartitions();
            for (Partition part : parts) {
              List<String> existingCols = part2Cols.get(part);
              if (existingCols == null) {
                existingCols = new ArrayList<String>();
              }
              existingCols.addAll(cols);
              part2Cols.put(part, existingCols);
            }
          } else {
            List<String> existingCols = tab2Cols.get(tbl);
            if (existingCols == null) {
              existingCols = new ArrayList<String>();
            }
            existingCols.addAll(cols);
            tab2Cols.put(tbl, existingCols);
          }
        }
      }
    }
  }

  private static void doAuthorizationV2(SessionState ss, HiveOperation op, Set<ReadEntity> inputs,
      Set<WriteEntity> outputs, String command, Map<String, List<String>> tab2cols,
      Map<String, List<String>> updateTab2Cols) throws HiveException {

    /* comment for reviewers -> updateTab2Cols needed to be separate from tab2cols because if I
    pass tab2cols to getHivePrivObjects for the output case it will trip up insert/selects,
    since the insert will get passed the columns from the select.
     */

    HiveAuthzContext.Builder authzContextBuilder = new HiveAuthzContext.Builder();
    authzContextBuilder.setUserIpAddress(ss.getUserIpAddress());
    authzContextBuilder.setForwardedAddresses(ss.getForwardedAddresses());
    authzContextBuilder.setCommandString(command);

    HiveOperationType hiveOpType = getHiveOperationType(op);
    List<HivePrivilegeObject> inputsHObjs = getHivePrivObjects(inputs, tab2cols);
    List<HivePrivilegeObject> outputHObjs = getHivePrivObjects(outputs, updateTab2Cols);

    ss.getAuthorizerV2().checkPrivileges(hiveOpType, inputsHObjs, outputHObjs, authzContextBuilder.build());
  }

  private static List<HivePrivilegeObject> getHivePrivObjects(
      Set<? extends Entity> privObjects, Map<String, List<String>> tableName2Cols) {
    List<HivePrivilegeObject> hivePrivobjs = new ArrayList<HivePrivilegeObject>();
    if(privObjects == null){
      return hivePrivobjs;
    }
    for(Entity privObject : privObjects){
      HivePrivilegeObjectType privObjType =
          AuthorizationUtils.getHivePrivilegeObjectType(privObject.getType());
      if(privObject.isDummy()) {
        //do not authorize dummy readEntity or writeEntity
        continue;
      }
      if(privObject instanceof ReadEntity && !((ReadEntity)privObject).isDirect()){
        // In case of views, the underlying views or tables are not direct dependencies
        // and are not used for authorization checks.
        // This ReadEntity represents one of the underlying tables/views, so skip it.
        // See description of the isDirect in ReadEntity
        continue;
      }
      if(privObject instanceof WriteEntity && ((WriteEntity)privObject).isTempURI()){
        //do not authorize temporary uris
        continue;
      }
      //support for authorization on partitions needs to be added
      String dbname = null;
      String objName = null;
      List<String> partKeys = null;
      List<String> columns = null;
      switch(privObject.getType()){
      case DATABASE:
        dbname = privObject.getDatabase().getName();
        break;
      case TABLE:
        dbname = privObject.getTable().getDbName();
        objName = privObject.getTable().getTableName();
        columns = tableName2Cols == null ? null :
            tableName2Cols.get(Table.getCompleteName(dbname, objName));
        break;
      case DFS_DIR:
      case LOCAL_DIR:
        objName = privObject.getD().toString();
        break;
      case FUNCTION:
        if(privObject.getDatabase() != null) {
          dbname = privObject.getDatabase().getName();
        }
        objName = privObject.getFunctionName();
        break;
      case DUMMYPARTITION:
      case PARTITION:
        // not currently handled
        continue;
        default:
          throw new AssertionError("Unexpected object type");
      }
      HivePrivObjectActionType actionType = AuthorizationUtils.getActionType(privObject);
      HivePrivilegeObject hPrivObject = new HivePrivilegeObject(privObjType, dbname, objName,
          partKeys, columns, actionType, null);
      hivePrivobjs.add(hPrivObject);
    }
    return hivePrivobjs;
  }

  private static HiveOperationType getHiveOperationType(HiveOperation op) {
    return HiveOperationType.valueOf(op.name());
  }

  /**
   * @return The current query plan associated with this Driver, if any.
   */
  public QueryPlan getPlan() {
    return plan;
  }

  /**
   * @return The current FetchTask associated with the Driver's plan, if any.
   */
  public FetchTask getFetchTask() {
    return fetchTask;
  }

  // Write the current set of valid transactions into the conf file so that it can be read by
  // the input format.
  private void recordValidTxns() throws LockException {
    HiveTxnManager txnMgr = SessionState.get().getTxnMgr();
    ValidTxnList txns = txnMgr.getValidTxns();
    String txnStr = txns.toString();
    conf.set(ValidTxnList.VALID_TXNS_KEY, txnStr);
    if(plan.getFetchTask() != null) {
      /**
       * This is needed for {@link HiveConf.ConfVars.HIVEFETCHTASKCONVERSION} optimization which
       * initializes JobConf in FetchOperator before recordValidTxns() but this has to be done
       * after locks are acquired to avoid race conditions in ACID.
       */
      plan.getFetchTask().setValidTxnList(txnStr);
    }
    LOG.debug("Encoding valid txns info " + txnStr + " txnid:" + txnMgr.getCurrentTxnId());
  }

  /**
   * Acquire read and write locks needed by the statement. The list of objects to be locked are
   * obtained from the inputs and outputs populated by the compiler. The lock acquisition scheme is
   * pretty simple. If all the locks cannot be obtained, error out. Deadlock is avoided by making
   * sure that the locks are lexicographically sorted.
   *
   * This method also records the list of valid transactions.  This must be done after any
   * transactions have been opened and locks acquired.
   * @param startTxnImplicitly in AC=false, the 1st DML starts a txn
   **/
  private int acquireLocksAndOpenTxn(boolean startTxnImplicitly) {
    PerfLogger perfLogger = SessionState.getPerfLogger();
    perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.ACQUIRE_READ_WRITE_LOCKS);

    SessionState ss = SessionState.get();
    HiveTxnManager txnMgr = ss.getTxnMgr();
    if(startTxnImplicitly) {
      assert !txnMgr.getAutoCommit();
    }

    try {
      // Don't use the userName member, as it may or may not have been set.  Get the value from
      // conf, which calls into getUGI to figure out who the process is running as.
      String userFromUGI;
      try {
        userFromUGI = conf.getUser();
      } catch (IOException e) {
        errorMessage = "FAILED: Error in determining user while acquiring locks: " + e.getMessage();
        SQLState = ErrorMsg.findSQLState(e.getMessage());
        downstreamError = e;
        console.printError(errorMessage,
            "\n" + org.apache.hadoop.util.StringUtils.stringifyException(e));
        return 10;
      }

      boolean initiatingTransaction = false;
      boolean readOnlyQueryInAutoCommit = false;
      if((txnMgr.getAutoCommit() && haveAcidWrite()) || plan.getOperation() == HiveOperation.START_TRANSACTION ||
        (!txnMgr.getAutoCommit() && startTxnImplicitly)) {
        if(txnMgr.isTxnOpen()) {
          throw new RuntimeException("Already have an open transaction txnid:" + txnMgr.getCurrentTxnId());
        }
        // We are writing to tables in an ACID compliant way, so we need to open a transaction
        txnMgr.openTxn(userFromUGI);
        initiatingTransaction = true;
      }
      else {
        readOnlyQueryInAutoCommit = txnMgr.getAutoCommit() && plan.getOperation() == HiveOperation.QUERY && !haveAcidWrite();
      }
      // Set the transaction id in all of the acid file sinks
      if (haveAcidWrite()) {
        for (FileSinkDesc desc : acidSinks) {
          desc.setTransactionId(txnMgr.getCurrentTxnId());
          desc.setStatementId(txnMgr.getStatementId());
        }
      }
      /*Note, we have to record snapshot after lock acquisition to prevent lost update problem
      consider 2 concurrent "update table T set x = x + 1".  1st will get the locks and the
      2nd will block until 1st one commits and only then lock in the snapshot, i.e. it will
      see the changes made by 1st one.  This takes care of autoCommit=true case.
      For multi-stmt txns this is not sufficient and will be managed via WriteSet tracking
      in the lock manager.*/
      txnMgr.acquireLocks(plan, ctx, userFromUGI);
      if(initiatingTransaction || (readOnlyQueryInAutoCommit && acidInQuery)) {
        //For multi-stmt txns we should record the snapshot when txn starts but
        // don't update it after that until txn completes.  Thus the check for {@code initiatingTransaction}
        //For autoCommit=true, Read-only statements, txn is implicit, i.e. lock in the snapshot
        //for each statement.
        recordValidTxns();
      }

      return 0;
    } catch (LockException e) {
      errorMessage = "FAILED: Error in acquiring locks: " + e.getMessage();
      SQLState = ErrorMsg.findSQLState(e.getMessage());
      downstreamError = e;
      console.printError(errorMessage, "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return 10;
    } finally {
      perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.ACQUIRE_READ_WRITE_LOCKS);
    }
  }

  private boolean haveAcidWrite() {
    return acidSinks != null && !acidSinks.isEmpty();
  }
  /**
   * @param commit if there is an open transaction and if true, commit,
   *               if false rollback.  If there is no open transaction this parameter is ignored.
   * @param txnManager an optional existing transaction manager retrieved earlier from the session
   *
   **/
  private void releaseLocksAndCommitOrRollback(boolean commit, HiveTxnManager txnManager)
      throws LockException {
    PerfLogger perfLogger = SessionState.getPerfLogger();
    perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.RELEASE_LOCKS);

    HiveTxnManager txnMgr;
    if (txnManager == null) {
      SessionState ss = SessionState.get();
      txnMgr = ss.getTxnMgr();
    } else {
      txnMgr = txnManager;
    }
    // If we've opened a transaction we need to commit or rollback rather than explicitly
    // releasing the locks.
    if (txnMgr.isTxnOpen()) {
      if (commit) {
        if(conf.getBoolVar(ConfVars.HIVE_IN_TEST) && conf.getBoolVar(ConfVars.HIVETESTMODEROLLBACKTXN)) {
          txnMgr.rollbackTxn();
        }
        else {
          txnMgr.commitTxn();//both commit & rollback clear ALL locks for this tx
        }
      } else {
        txnMgr.rollbackTxn();
      }
    } else {
      //since there is no tx, we only have locks for current query (if any)
      if (ctx != null && ctx.getHiveLocks() != null) {
        hiveLocks.addAll(ctx.getHiveLocks());
      }
      txnMgr.releaseLocks(hiveLocks);
    }
    hiveLocks.clear();
    if (ctx != null) {
      ctx.setHiveLocks(null);
    }

    perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.RELEASE_LOCKS);
  }

  /**
   * Release some resources after a query is executed
   * while keeping the result around.
   */
  private void releaseResources() {
    if (SessionState.get() != null) {
      SessionState.get().getLineageState().clear();
    }

    if (plan != null) {
      fetchTask = plan.getFetchTask();
      if (fetchTask != null) {
        fetchTask.setDriverContext(null);
        fetchTask.setQueryPlan(null);
      }
    }

    if (driverCxt != null) {
      driverCxt.shutdown();
      driverCxt = null;
    }
    plan = null;
  }

  @Override
  public CommandProcessorResponse run(String command)
      throws CommandNeedRetryException {
    return run(command, false);
  }

  public CommandProcessorResponse run()
      throws CommandNeedRetryException {
    return run(null, true);
  }

  public CommandProcessorResponse run(String command, boolean alreadyCompiled)
        throws CommandNeedRetryException {
    CommandProcessorResponse cpr;
    try {
      cpr = runInternal(command, alreadyCompiled);
    } finally {
      releaseResources();
    }

    if(cpr.getResponseCode() == 0) {
      return cpr;
    }
    SessionState ss = SessionState.get();
    if(ss == null) {
      return cpr;
    }
    MetaDataFormatter mdf = MetaDataFormatUtils.getFormatter(ss.getConf());
    if(!(mdf instanceof JsonMetaDataFormatter)) {
      return cpr;
    }
    /*Here we want to encode the error in machine readable way (e.g. JSON)
     * Ideally, errorCode would always be set to a canonical error defined in ErrorMsg.
     * In practice that is rarely the case, so the messy logic below tries to tease
     * out canonical error code if it can.  Exclude stack trace from output when
     * the error is a specific/expected one.
     * It's written to stdout for backward compatibility (WebHCat consumes it).*/
    try {
      if(downstreamError == null) {
        mdf.error(ss.out, errorMessage, cpr.getResponseCode(), SQLState);
        return cpr;
      }
      ErrorMsg canonicalErr = ErrorMsg.getErrorMsg(cpr.getResponseCode());
      if(canonicalErr != null && canonicalErr != ErrorMsg.GENERIC_ERROR) {
        /*Some HiveExceptions (e.g. SemanticException) don't set
          canonical ErrorMsg explicitly, but there is logic
          (e.g. #compile()) to find an appropriate canonical error and
          return its code as error code. In this case we want to
          preserve it for downstream code to interpret*/
        mdf.error(ss.out, errorMessage, cpr.getResponseCode(), SQLState, null);
        return cpr;
      }
      if(downstreamError instanceof HiveException) {
        HiveException rc = (HiveException) downstreamError;
        mdf.error(ss.out, errorMessage,
                rc.getCanonicalErrorMsg().getErrorCode(), SQLState,
                rc.getCanonicalErrorMsg() == ErrorMsg.GENERIC_ERROR ?
                        org.apache.hadoop.util.StringUtils.stringifyException(rc)
                        : null);
      }
      else {
        ErrorMsg canonicalMsg =
                ErrorMsg.getErrorMsg(downstreamError.getMessage());
        mdf.error(ss.out, errorMessage, canonicalMsg.getErrorCode(),
                SQLState, org.apache.hadoop.util.StringUtils.
                stringifyException(downstreamError));
      }
    }
    catch(HiveException ex) {
      console.printError("Unable to JSON-encode the error",
              org.apache.hadoop.util.StringUtils.stringifyException(ex));
    }
    return cpr;
  }

  public CommandProcessorResponse compileAndRespond(String command) {
    return createProcessorResponse(compileInternal(command));
  }

  private static final ReentrantLock globalCompileLock = new ReentrantLock();
  private int compileInternal(String command) {
    int ret;
    final ReentrantLock compileLock = tryAcquireCompileLock(isParallelEnabled,
      command);
    if (compileLock == null) {
      return ErrorMsg.COMPILE_LOCK_TIMED_OUT.getErrorCode();
    }

    try {
      ret = compile(command);
    } finally {
      compileLock.unlock();
    }

    if (ret != 0) {
      try {
        releaseLocksAndCommitOrRollback(false, null);
      } catch (LockException e) {
        LOG.warn("Exception in releasing locks. "
            + org.apache.hadoop.util.StringUtils.stringifyException(e));
      }
    }

    //Save compile-time PerfLogging for WebUI.
    //Execution-time Perf logs are done by either another thread's PerfLogger
    //or a reset PerfLogger.
    PerfLogger perfLogger = SessionState.getPerfLogger();
    queryDisplay.setPerfLogStarts(QueryDisplay.Phase.COMPILATION, perfLogger.getStartTimes());
    queryDisplay.setPerfLogEnds(QueryDisplay.Phase.COMPILATION, perfLogger.getEndTimes());
    return ret;
  }

  /**
   * Acquires the compile lock. If the compile lock wait timeout is configured,
   * it will acquire the lock if it is not held by another thread within the given
   * waiting time.
   * @return the ReentrantLock object if the lock was successfully acquired,
   *         or {@code null} if compile lock wait timeout is configured and
   *         either the waiting time elapsed before the lock could be acquired
   *         or if the current thread is interrupted.
   */
  private ReentrantLock tryAcquireCompileLock(boolean isParallelEnabled,
    String command) {
    final ReentrantLock compileLock = isParallelEnabled ?
        SessionState.get().getCompileLock() : globalCompileLock;
    long maxCompileLockWaitTime = HiveConf.getTimeVar(
      this.conf, ConfVars.HIVE_SERVER2_COMPILE_LOCK_TIMEOUT,
      TimeUnit.SECONDS);

    final String lockAcquiredMsg = "Acquired the compile lock.";
    // First shot without waiting.
    try {
      if (compileLock.tryLock(0, TimeUnit.SECONDS)) {
        LOG.debug(lockAcquiredMsg);
        return compileLock;
      }
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      if (LOG.isDebugEnabled()) {
        LOG.debug("Interrupted Exception ignored", e);
      }
      return null;
    }

    // If the first shot fails, then we log the waiting messages.
    if (LOG.isDebugEnabled()) {
      LOG.debug("Waiting to acquire compile lock: " + command);
    }

    OperationLog ol = OperationLog.getCurrentOperationLog();
    if (ol != null) {
      ol.writeOperationLog(LoggingLevel.EXECUTION, "Waiting to acquire compile lock.\n");
    }

    if (maxCompileLockWaitTime > 0) {
      try {
        if(!compileLock.tryLock(maxCompileLockWaitTime, TimeUnit.SECONDS)) {
          errorMessage = ErrorMsg.COMPILE_LOCK_TIMED_OUT.getErrorCodedMsg();
          LOG.error(errorMessage + ": " + command);
          return null;
        }
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
        if (LOG.isDebugEnabled()) {
          LOG.debug("Interrupted Exception ignored", e);
        }
        return null;
      }
    } else {
      compileLock.lock();
    }

    LOG.debug(lockAcquiredMsg);
    if (ol != null) {
        ol.writeOperationLog(LoggingLevel.EXECUTION, lockAcquiredMsg + "\n");
    }
    return compileLock;
  }

  private CommandProcessorResponse runInternal(String command, boolean alreadyCompiled)
      throws CommandNeedRetryException {
    errorMessage = null;
    SQLState = null;
    downstreamError = null;

    HiveDriverRunHookContext hookContext = new HiveDriverRunHookContextImpl(conf, command);
    // Get all the driver run hooks and pre-execute them.
    List<HiveDriverRunHook> driverRunHooks;
    try {
      driverRunHooks = getHooks(HiveConf.ConfVars.HIVE_DRIVER_RUN_HOOKS,
          HiveDriverRunHook.class);
      for (HiveDriverRunHook driverRunHook : driverRunHooks) {
          driverRunHook.preDriverRun(hookContext);
      }
    } catch (Exception e) {
      errorMessage = "FAILED: Hive Internal Error: " + Utilities.getNameMessage(e);
      SQLState = ErrorMsg.findSQLState(e.getMessage());
      downstreamError = e;
      console.printError(errorMessage + "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return createProcessorResponse(12);
    }

    PerfLogger perfLogger = null;

    int ret;
    if (!alreadyCompiled) {
      // compile internal will automatically reset the perf logger
      ret = compileInternal(command);
      // then we continue to use this perf logger
      perfLogger = SessionState.getPerfLogger();
      if (ret != 0) {
        return createProcessorResponse(ret);
      }
    } else {
      // reuse existing perf logger.
      perfLogger = SessionState.getPerfLogger();
      // Since we're reusing the compiled plan, we need to update its start time for current run
      plan.setQueryStartTime(perfLogger.getStartTime(PerfLogger.DRIVER_RUN));
    }
    // the reason that we set the txn manager for the cxt here is because each
    // query has its own ctx object. The txn mgr is shared across the
    // same instance of Driver, which can run multiple queries.
    HiveTxnManager txnManager = SessionState.get().getTxnMgr();
    ctx.setHiveTxnManager(txnManager);

    boolean startTxnImplicitly = false;
    {
      //this block ensures op makes sense in given context, e.g. COMMIT is valid only if txn is open
      //DDL is not allowed in a txn, etc.
      //an error in an open txn does a rollback of the txn
      if (txnManager.isTxnOpen() && !plan.getOperation().isAllowedInTransaction()) {
        assert !txnManager.getAutoCommit() : "didn't expect AC=true";
        return rollback(new CommandProcessorResponse(12, ErrorMsg.OP_NOT_ALLOWED_IN_TXN, null,
          plan.getOperationName(), Long.toString(txnManager.getCurrentTxnId())));
      }
      if(!txnManager.isTxnOpen() && plan.getOperation().isRequiresOpenTransaction()) {
        return rollback(new CommandProcessorResponse(12, ErrorMsg.OP_NOT_ALLOWED_WITHOUT_TXN, null, plan.getOperationName()));
      }
      if(!txnManager.isTxnOpen() && plan.getOperation() == HiveOperation.QUERY && !txnManager.getAutoCommit()) {
        //this effectively makes START TRANSACTION optional and supports JDBC setAutoCommit(false) semantics
        //also, indirectly allows DDL to be executed outside a txn context
        startTxnImplicitly = true;
      }
      if(txnManager.getAutoCommit() && plan.getOperation() == HiveOperation.START_TRANSACTION) {
          return rollback(new CommandProcessorResponse(12, ErrorMsg.OP_NOT_ALLOWED_IN_AUTOCOMMIT, null, plan.getOperationName()));
      }
    }
    if(plan.getOperation() == HiveOperation.SET_AUTOCOMMIT) {
      try {
        if(plan.getAutoCommitValue() && !txnManager.getAutoCommit()) {
          /*here, if there is an open txn, we want to commit it; this behavior matches
          * https://docs.oracle.com/javase/6/docs/api/java/sql/Connection.html#setAutoCommit(boolean)*/
          releaseLocksAndCommitOrRollback(true, null);
          txnManager.setAutoCommit(true);
        }
        else if(!plan.getAutoCommitValue() && txnManager.getAutoCommit()) {
          txnManager.setAutoCommit(false);
        }
        else {/*didn't change autoCommit value - no-op*/}
      }
      catch(LockException e) {
        return handleHiveException(e, 12);
      }
    }

    if (requiresLock()) {
      ret = acquireLocksAndOpenTxn(startTxnImplicitly);
      if (ret != 0) {
        return rollback(createProcessorResponse(ret));
      }
    }
    ret = execute();
    if (ret != 0) {
      //if needRequireLock is false, the release here will do nothing because there is no lock
      return rollback(createProcessorResponse(ret));
    }

    //if needRequireLock is false, the release here will do nothing because there is no lock
    try {
      if(txnManager.getAutoCommit() || plan.getOperation() == HiveOperation.COMMIT) {
        releaseLocksAndCommitOrRollback(true, null);
      }
      else if(plan.getOperation() == HiveOperation.ROLLBACK) {
        releaseLocksAndCommitOrRollback(false, null);
      }
      else {
        //txn (if there is one started) is not finished
      }
    } catch (LockException e) {
      return handleHiveException(e, 12);
    }

    perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.DRIVER_RUN);
    queryDisplay.setPerfLogStarts(QueryDisplay.Phase.EXECUTION, perfLogger.getStartTimes());
    queryDisplay.setPerfLogEnds(QueryDisplay.Phase.EXECUTION, perfLogger.getEndTimes());

    // Take all the driver run hooks and post-execute them.
    try {
      for (HiveDriverRunHook driverRunHook : driverRunHooks) {
          driverRunHook.postDriverRun(hookContext);
      }
    } catch (Exception e) {
      errorMessage = "FAILED: Hive Internal Error: " + Utilities.getNameMessage(e);
      SQLState = ErrorMsg.findSQLState(e.getMessage());
      downstreamError = e;
      console.printError(errorMessage + "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return createProcessorResponse(12);
    }

    return createProcessorResponse(ret);
  }

  private CommandProcessorResponse rollback(CommandProcessorResponse cpr) {
    //console.printError(cpr.toString());
    try {
      releaseLocksAndCommitOrRollback(false, null);
    }
    catch (LockException e) {
      LOG.error("rollback() FAILED: " + cpr);//make sure not to loose
      handleHiveException(e, 12, "Additional info in hive.log at \"rollback() FAILED\"");
    }
    return cpr;
  }
  private CommandProcessorResponse handleHiveException(HiveException e, int ret) {
    return handleHiveException(e, ret, null);
  }
  private CommandProcessorResponse handleHiveException(HiveException e, int ret, String rootMsg) {
    errorMessage = "FAILED: Hive Internal Error: " + Utilities.getNameMessage(e);
    if(rootMsg != null) {
      errorMessage += "\n" + rootMsg;
    }
    SQLState = e.getCanonicalErrorMsg() != null ?
      e.getCanonicalErrorMsg().getSQLState() : ErrorMsg.findSQLState(e.getMessage());
    downstreamError = e;
    console.printError(errorMessage + "\n"
      + org.apache.hadoop.util.StringUtils.stringifyException(e));
    return createProcessorResponse(ret);
  }
  private boolean requiresLock() {
    if (!checkConcurrency()) {
      return false;
    }
    // Lock operations themselves don't require the lock.
    if (isExplicitLockOperation()){
      return false;
    }
    if (!HiveConf.getBoolVar(conf, ConfVars.HIVE_LOCK_MAPRED_ONLY)) {
      return true;
    }
    Queue<Task<? extends Serializable>> taskQueue = new LinkedList<Task<? extends Serializable>>();
    taskQueue.addAll(plan.getRootTasks());
    while (taskQueue.peek() != null) {
      Task<? extends Serializable> tsk = taskQueue.remove();
      if (tsk.requireLock()) {
        return true;
      }
      if (tsk instanceof ConditionalTask) {
        taskQueue.addAll(((ConditionalTask)tsk).getListTasks());
      }
      if (tsk.getChildTasks()!= null) {
        taskQueue.addAll(tsk.getChildTasks());
      }
      // does not add back up task here, because back up task should be the same
      // type of the original task.
    }
    return false;
  }

  private boolean isExplicitLockOperation() {
    HiveOperation currentOpt = plan.getOperation();
    if (currentOpt != null) {
      switch (currentOpt) {
      case LOCKDB:
      case UNLOCKDB:
      case LOCKTABLE:
      case UNLOCKTABLE:
        return true;
      default:
        return false;
      }
    }
    return false;
  }

  private CommandProcessorResponse createProcessorResponse(int ret) {
    SessionState.getPerfLogger().cleanupPerfLogMetrics();
    queryDisplay.setErrorMessage(errorMessage);
    return new CommandProcessorResponse(ret, errorMessage, SQLState, downstreamError);
  }

  /**
   * Returns a set of hooks specified in a configuration variable.
   * See getHooks(HiveConf.ConfVars hookConfVar, Class<T> clazz)
   */
  private List<Hook> getHooks(HiveConf.ConfVars hookConfVar) throws Exception {
    return getHooks(hookConfVar, Hook.class);
  }

  /**
   * Returns the hooks specified in a configuration variable.
   *
   * @param hookConfVar The configuration variable specifying a comma separated list of the hook
   *                    class names.
   * @param clazz       The super type of the hooks.
   * @return            A list of the hooks cast as the type specified in clazz, in the order
   *                    they are listed in the value of hookConfVar
   * @throws Exception
   */
  private <T extends Hook> List<T> getHooks(ConfVars hookConfVar,
      Class<T> clazz) throws Exception {
    try {
      return HookUtils.getHooks(conf, hookConfVar, clazz);
    } catch (ClassNotFoundException e) {
      console.printError(hookConfVar.varname + " Class not found:" + e.getMessage());
      throw e;
    }
  }

  public int execute() throws CommandNeedRetryException {
    PerfLogger perfLogger = SessionState.getPerfLogger();
    perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.DRIVER_EXECUTE);
    boolean noName = StringUtils.isEmpty(conf.get(MRJobConfig.JOB_NAME));
    int maxlen = conf.getIntVar(HiveConf.ConfVars.HIVEJOBNAMELENGTH);

    String queryId = plan.getQueryId();
    // Get the query string from the conf file as the compileInternal() method might
    // hide sensitive information during query redaction.
    String queryStr = conf.getQueryString();

    maxthreads = HiveConf.getIntVar(conf, HiveConf.ConfVars.EXECPARALLETHREADNUMBER);

    HookContext hookContext = null;

    try {
      LOG.info("Executing command(queryId=" + queryId + "): " + queryStr);
      // compile and execute can get called from different threads in case of HS2
      // so clear timing in this thread's Hive object before proceeding.
      Hive.get().clearMetaCallTiming();

      plan.setStarted();

      if (SessionState.get() != null) {
        SessionState.get().getHiveHistory().startQuery(queryStr,
            conf.getVar(HiveConf.ConfVars.HIVEQUERYID));
        SessionState.get().getHiveHistory().logPlanProgress(plan);
      }
      resStream = null;

      SessionState ss = SessionState.get();
      hookContext = new HookContext(plan, queryState, ctx.getPathToCS(), ss.getUserName(),
          ss.getUserIpAddress(), operationId);
      hookContext.setHookType(HookContext.HookType.PRE_EXEC_HOOK);

      for (Hook peh : getHooks(HiveConf.ConfVars.PREEXECHOOKS)) {
        if (peh instanceof ExecuteWithHookContext) {
          perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.PRE_HOOK + peh.getClass().getName());

          ((ExecuteWithHookContext) peh).run(hookContext);

          perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.PRE_HOOK + peh.getClass().getName());
        } else if (peh instanceof PreExecute) {
          perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.PRE_HOOK + peh.getClass().getName());

          ((PreExecute) peh).run(SessionState.get(), plan.getInputs(), plan.getOutputs(),
              Utils.getUGI());

          perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.PRE_HOOK + peh.getClass().getName());
        }
      }
      setQueryDisplays(plan.getRootTasks());
      int mrJobs = Utilities.getMRTasks(plan.getRootTasks()).size();
      int jobs = mrJobs
        + Utilities.getTezTasks(plan.getRootTasks()).size()
        + Utilities.getSparkTasks(plan.getRootTasks()).size();
      if (jobs > 0) {
        logMrWarning(mrJobs);
        console.printInfo("Query ID = " + plan.getQueryId());
        console.printInfo("Total jobs = " + jobs);
      }
      if (SessionState.get() != null) {
        SessionState.get().getHiveHistory().setQueryProperty(queryId, Keys.QUERY_NUM_TASKS,
            String.valueOf(jobs));
        SessionState.get().getHiveHistory().setIdToTableMap(plan.getIdToTableNameMap());
      }
      String jobname = Utilities.abbreviate(queryStr, maxlen - 6);

      // A runtime that launches runnable tasks as separate Threads through
      // TaskRunners
      // As soon as a task isRunnable, it is put in a queue
      // At any time, at most maxthreads tasks can be running
      // The main thread polls the TaskRunners to check if they have finished.

      DriverContext driverCxt = new DriverContext(ctx);
      driverCxt.prepare(plan);

      ctx.setHDFSCleanup(true);

      this.driverCxt = driverCxt; // for canceling the query (should be bound to session?)

      SessionState.get().setMapRedStats(new LinkedHashMap<String, MapRedStats>());
      SessionState.get().setStackTraces(new HashMap<String, List<List<String>>>());
      SessionState.get().setLocalMapRedErrors(new HashMap<String, List<String>>());

      // Add root Tasks to runnable
      for (Task<? extends Serializable> tsk : plan.getRootTasks()) {
        // This should never happen, if it does, it's a bug with the potential to produce
        // incorrect results.
        assert tsk.getParentTasks() == null || tsk.getParentTasks().isEmpty();
        driverCxt.addToRunnable(tsk);
      }

      perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.RUN_TASKS);
      // Loop while you either have tasks running, or tasks queued up
      while (!destroyed && driverCxt.isRunning()) {

        // Launch upto maxthreads tasks
        Task<? extends Serializable> task;
        while ((task = driverCxt.getRunnable(maxthreads)) != null) {
          TaskRunner runner = launchTask(task, queryId, noName, jobname, jobs, driverCxt);
          if (!runner.isRunning()) {
            break;
          }
        }

        // poll the Tasks to see which one completed
        TaskRunner tskRun = driverCxt.pollFinished();
        if (tskRun == null) {
          continue;
        }
        hookContext.addCompleteTask(tskRun);
        queryDisplay.setTaskResult(tskRun.getTask().getId(), tskRun.getTaskResult());

        Task<? extends Serializable> tsk = tskRun.getTask();
        TaskResult result = tskRun.getTaskResult();

        int exitVal = result.getExitVal();
        if (exitVal != 0) {
          if (tsk.ifRetryCmdWhenFail()) {
            driverCxt.shutdown();
            // in case we decided to run everything in local mode, restore the
            // the jobtracker setting to its initial value
            ctx.restoreOriginalTracker();
            throw new CommandNeedRetryException();
          }
          Task<? extends Serializable> backupTask = tsk.getAndInitBackupTask();
          if (backupTask != null) {
            setErrorMsgAndDetail(exitVal, result.getTaskError(), tsk);
            console.printError(errorMessage);
            errorMessage = "ATTEMPT: Execute BackupTask: " + backupTask.getClass().getName();
            console.printError(errorMessage);

            // add backup task to runnable
            if (DriverContext.isLaunchable(backupTask)) {
              driverCxt.addToRunnable(backupTask);
            }
            continue;

          } else {
            setErrorMsgAndDetail(exitVal, result.getTaskError(), tsk);
            invokeFailureHooks(perfLogger, hookContext,
              errorMessage + Strings.nullToEmpty(tsk.getDiagnosticsMessage()), result.getTaskError());
            SQLState = "08S01";
            console.printError(errorMessage);
            driverCxt.shutdown();
            // in case we decided to run everything in local mode, restore the
            // the jobtracker setting to its initial value
            ctx.restoreOriginalTracker();
            return exitVal;
          }
        }

        driverCxt.finished(tskRun);

        if (SessionState.get() != null) {
          SessionState.get().getHiveHistory().setTaskProperty(queryId, tsk.getId(),
              Keys.TASK_RET_CODE, String.valueOf(exitVal));
          SessionState.get().getHiveHistory().endTask(queryId, tsk);
        }

        if (tsk.getChildTasks() != null) {
          for (Task<? extends Serializable> child : tsk.getChildTasks()) {
            if (DriverContext.isLaunchable(child)) {
              driverCxt.addToRunnable(child);
            }
          }
        }
      }
      perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.RUN_TASKS);

      // in case we decided to run everything in local mode, restore the
      // the jobtracker setting to its initial value
      ctx.restoreOriginalTracker();

      if (driverCxt.isShutdown()) {
        SQLState = "HY008";
        errorMessage = "FAILED: Operation cancelled";
        invokeFailureHooks(perfLogger, hookContext, errorMessage, null);
        console.printError(errorMessage);
        return 1000;
      }

      // remove incomplete outputs.
      // Some incomplete outputs may be added at the beginning, for eg: for dynamic partitions.
      // remove them
      HashSet<WriteEntity> remOutputs = new LinkedHashSet<WriteEntity>();
      for (WriteEntity output : plan.getOutputs()) {
        if (!output.isComplete()) {
          remOutputs.add(output);
        }
      }

      for (WriteEntity output : remOutputs) {
        plan.getOutputs().remove(output);
      }

      hookContext.setHookType(HookContext.HookType.POST_EXEC_HOOK);
      // Get all the post execution hooks and execute them.
      for (Hook peh : getHooks(HiveConf.ConfVars.POSTEXECHOOKS)) {
        if (peh instanceof ExecuteWithHookContext) {
          perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.POST_HOOK + peh.getClass().getName());

          ((ExecuteWithHookContext) peh).run(hookContext);

          perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.POST_HOOK + peh.getClass().getName());
        } else if (peh instanceof PostExecute) {
          perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.POST_HOOK + peh.getClass().getName());

          ((PostExecute) peh).run(SessionState.get(), plan.getInputs(), plan.getOutputs(),
              (SessionState.get() != null ? SessionState.get().getLineageState().getLineageInfo()
                  : null), Utils.getUGI());

          perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.POST_HOOK + peh.getClass().getName());
        }
      }


      if (SessionState.get() != null) {
        SessionState.get().getHiveHistory().setQueryProperty(queryId, Keys.QUERY_RET_CODE,
            String.valueOf(0));
        SessionState.get().getHiveHistory().printRowCount(queryId);
      }
    } catch (CommandNeedRetryException e) {
      throw e;
    } catch (Exception e) {
      ctx.restoreOriginalTracker();
      if (SessionState.get() != null) {
        SessionState.get().getHiveHistory().setQueryProperty(queryId, Keys.QUERY_RET_CODE,
            String.valueOf(12));
      }
      // TODO: do better with handling types of Exception here
      errorMessage = "FAILED: Hive Internal Error: " + Utilities.getNameMessage(e);
      if (hookContext != null) {
        try {
          invokeFailureHooks(perfLogger, hookContext, errorMessage, e);
        } catch (Exception t) {
          LOG.warn("Failed to invoke failure hook", t);
        }
      }
      SQLState = "08S01";
      downstreamError = e;
      console.printError(errorMessage + "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return (12);
    } finally {
      if (SessionState.get() != null) {
        SessionState.get().getHiveHistory().endQuery(queryId);
      }
      if (noName) {
        conf.set(MRJobConfig.JOB_NAME, "");
      }
      double duration = perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.DRIVER_EXECUTE)/1000.00;

      ImmutableMap<String, Long> executionHMSTimings = dumpMetaCallTimingWithoutEx("execution");
      queryDisplay.setHmsTimings(QueryDisplay.Phase.EXECUTION, executionHMSTimings);

      Map<String, MapRedStats> stats = SessionState.get().getMapRedStats();
      if (stats != null && !stats.isEmpty()) {
        long totalCpu = 0;
        console.printInfo("MapReduce Jobs Launched: ");
        for (Map.Entry<String, MapRedStats> entry : stats.entrySet()) {
          console.printInfo("Stage-" + entry.getKey() + ": " + entry.getValue());
          totalCpu += entry.getValue().getCpuMSec();
        }
        console.printInfo("Total MapReduce CPU Time Spent: " + Utilities.formatMsecToStr(totalCpu));
      }
      LOG.info("Completed executing command(queryId=" + queryId + "); Time taken: " + duration + " seconds");
    }

    releasePlan(plan);

    if (console != null) {
      console.printInfo("OK");
    }

    return (0);
  }

  private synchronized void releasePlan(QueryPlan plan) {
    // Plan maybe null if Driver.close is called in another thread for the same Driver object
    if (plan != null) {
      plan.setDone();
      if (SessionState.get() != null) {
        try {
          SessionState.get().getHiveHistory().logPlanProgress(plan);
        } catch (Exception e) {
          // Log and ignore
          LOG.warn("Could not log query plan progress", e);
        }
      }
    }
  }

  private void setQueryDisplays(List<Task<? extends Serializable>> tasks) {
    if (tasks != null) {
      for (Task<? extends Serializable> task : tasks) {
        task.setQueryDisplay(queryDisplay);
        setQueryDisplays(task.getDependentTasks());
      }
    }
  }

  private void logMrWarning(int mrJobs) {
    if (mrJobs <= 0 || !("mr".equals(HiveConf.getVar(conf, ConfVars.HIVE_EXECUTION_ENGINE)))) {
      return;
    }
    String warning = HiveConf.generateMrDeprecationWarning();
    LOG.warn(warning);
    warning = "WARNING: " + warning;
    console.printInfo(warning);
    // Propagate warning to beeline via operation log.
    OperationLog ol = OperationLog.getCurrentOperationLog();
    if (ol != null) {
      ol.writeOperationLog(LoggingLevel.EXECUTION, warning + "\n");
    }
  }

  private void setErrorMsgAndDetail(int exitVal, Throwable downstreamError, Task tsk) {
    this.downstreamError = downstreamError;
    errorMessage = "FAILED: Execution Error, return code " + exitVal + " from " + tsk.getClass().getName();
    if(downstreamError != null) {
      //here we assume that upstream code may have parametrized the msg from ErrorMsg
      //so we want to keep it
      errorMessage += ". " + downstreamError.getMessage();
    }
    else {
      ErrorMsg em = ErrorMsg.getErrorMsg(exitVal);
      if (em != null) {
        errorMessage += ". " +  em.getMsg();
      }
    }
  }

  private void invokeFailureHooks(PerfLogger perfLogger,
      HookContext hookContext, String errorMessage, Throwable exception) throws Exception {
    hookContext.setHookType(HookContext.HookType.ON_FAILURE_HOOK);
    hookContext.setErrorMessage(errorMessage);
    hookContext.setException(exception);
    // Get all the failure execution hooks and execute them.
    for (Hook ofh : getHooks(HiveConf.ConfVars.ONFAILUREHOOKS)) {
      perfLogger.PerfLogBegin(CLASS_NAME, PerfLogger.FAILURE_HOOK + ofh.getClass().getName());

      ((ExecuteWithHookContext) ofh).run(hookContext);

      perfLogger.PerfLogEnd(CLASS_NAME, PerfLogger.FAILURE_HOOK + ofh.getClass().getName());
    }
  }

  /**
   * Launches a new task
   *
   * @param tsk
   *          task being launched
   * @param queryId
   *          Id of the query containing the task
   * @param noName
   *          whether the task has a name set
   * @param jobname
   *          name of the task, if it is a map-reduce job
   * @param jobs
   *          number of map-reduce jobs
   * @param cxt
   *          the driver context
   */
  private TaskRunner launchTask(Task<? extends Serializable> tsk, String queryId, boolean noName,
      String jobname, int jobs, DriverContext cxt) throws HiveException {
    if (SessionState.get() != null) {
      SessionState.get().getHiveHistory().startTask(queryId, tsk, tsk.getClass().getName());
    }
    if (tsk.isMapRedTask() && !(tsk instanceof ConditionalTask)) {
      if (noName) {
        conf.set(MRJobConfig.JOB_NAME, jobname + "(" + tsk.getId() + ")");
      }
      conf.set("mapreduce.workflow.node.name", tsk.getId());
      Utilities.setWorkflowAdjacencies(conf, plan);
      cxt.incCurJobNo(1);
      console.printInfo("Launching Job " + cxt.getCurJobNo() + " out of " + jobs);
    }
    tsk.initialize(queryState, plan, cxt, ctx.getOpContext());
    TaskResult tskRes = new TaskResult();
    TaskRunner tskRun = new TaskRunner(tsk, tskRes);

    cxt.launching(tskRun);
    // Launch Task
    if (HiveConf.getBoolVar(conf, HiveConf.ConfVars.EXECPARALLEL) && tsk.isMapRedTask()) {
      // Launch it in the parallel mode, as a separate thread only for MR tasks
      if (LOG.isInfoEnabled()){
        LOG.info("Starting task [" + tsk + "] in parallel");
      }
      tskRun.setOperationLog(OperationLog.getCurrentOperationLog());
      tskRun.start();
    } else {
      if (LOG.isInfoEnabled()){
        LOG.info("Starting task [" + tsk + "] in serial mode");
      }
      tskRun.runSequential();
    }
    return tskRun;
  }

  public boolean isFetchingTable() {
    return fetchTask != null;
  }

  @SuppressWarnings("unchecked")
  public boolean getResults(List res) throws IOException, CommandNeedRetryException {
    if (destroyed) {
      throw new IOException("FAILED: Operation cancelled");
    }
    if (isFetchingTable()) {
      /**
       * If resultset serialization to thrift object is enabled, and if the destination table is
       * indeed written using ThriftJDBCBinarySerDe, read one row from the output sequence file,
       * since it is a blob of row batches.
       */
      if (fetchTask.getWork().isHiveServerQuery() && HiveConf.getBoolVar(conf,
          HiveConf.ConfVars.HIVE_SERVER2_THRIFT_RESULTSET_SERIALIZE_IN_TASKS)
          && (fetchTask.getTblDesc().getSerdeClassName()
              .equalsIgnoreCase(ThriftJDBCBinarySerDe.class.getName()))) {
        maxRows = 1;
      }
      fetchTask.setMaxRows(maxRows);
      return fetchTask.fetch(res);
    }

    if (resStream == null) {
      resStream = ctx.getStream();
    }
    if (resStream == null) {
      return false;
    }

    int numRows = 0;
    String row = null;

    while (numRows < maxRows) {
      if (resStream == null) {
        if (numRows > 0) {
          return true;
        } else {
          return false;
        }
      }

      bos.reset();
      Utilities.StreamStatus ss;
      try {
        ss = Utilities.readColumn(resStream, bos);
        if (bos.getLength() > 0) {
          row = new String(bos.getData(), 0, bos.getLength(), "UTF-8");
        } else if (ss == Utilities.StreamStatus.TERMINATED) {
          row = new String();
        }

        if (row != null) {
          numRows++;
          res.add(row);
        }
        row = null;
      } catch (IOException e) {
        console.printError("FAILED: Unexpected IO exception : " + e.getMessage());
        return false;
      }

      if (ss == Utilities.StreamStatus.EOF) {
        resStream = ctx.getStream();
      }
    }
    return true;
  }

  public void resetFetch() throws IOException {
    if (isFetchingTable()) {
      try {
        fetchTask.clearFetch();
      } catch (Exception e) {
        throw new IOException("Error closing the current fetch task", e);
      }
      // FetchTask should not depend on the plan.
      fetchTask.initialize(queryState, null, null, ctx.getOpContext());
    } else {
      ctx.resetStream();
      resStream = null;
    }
  }

  public int getTryCount() {
    return tryCount;
  }

  public void setTryCount(int tryCount) {
    this.tryCount = tryCount;
  }

  public int close() {
    try {
      try {
        releaseResources();
      } catch (Exception e) {
        LOG.info("Exception while releasing resources", e);
      }
      if (fetchTask != null) {
        try {
          fetchTask.clearFetch();
        } catch (Exception e) {
          LOG.debug(" Exception while clearing the Fetch task ", e);
        }
        fetchTask = null;
      }
      if (ctx != null) {
        ctx.clear();
        if (ctx.getHiveLocks() != null) {
          hiveLocks.addAll(ctx.getHiveLocks());
          ctx.setHiveLocks(null);
        }
        ctx = null;
      }
      if (null != resStream) {
        try {
          ((FSDataInputStream) resStream).close();
        } catch (Exception e) {
          LOG.debug(" Exception while closing the resStream ", e);
        }
      }
    } catch (Exception e) {
      console.printError("FAILED: Hive Internal Error: " + Utilities.getNameMessage(e) + "\n"
          + org.apache.hadoop.util.StringUtils.stringifyException(e));
      return 13;
    }

    return 0;
  }

  public void destroy() {
    if (destroyed) {
      return;
    }
    destroyed = true;
    if (!hiveLocks.isEmpty()) {
      try {
        releaseLocksAndCommitOrRollback(false, null);
      } catch (LockException e) {
        LOG.warn("Exception when releasing locking in destroy: " +
            e.getMessage());
      }
    }
    ShutdownHookManager.removeShutdownHook(shutdownRunner);
  }

  public org.apache.hadoop.hive.ql.plan.api.Query getQueryPlan() throws IOException {
    return plan.getQueryPlan();
  }

  public String getErrorMsg() {
    return errorMessage;
  }


  public QueryDisplay getQueryDisplay() {
    return queryDisplay;
  }

  /**
   * Set the HS2 operation handle's guid string
   * @param opId base64 encoded guid string
   */
  public void setOperationId(String opId) {
    this.operationId = opId;
  }

  /** 
   * Resets QueryState to get new queryId on Driver reuse.
   */
  public void resetQueryState() {
    // Note: Driver cleanup for reuse at this point is not very clear. The assumption here is that
    // repeated compile/execute calls create new contexts, plan, etc., so we don't need to worry
    // propagating queryState into those existing fields, or resetting them.
    releaseResources();
    this.queryState = new QueryState(queryState.getConf());
  }
}