content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.backend.mysql.nio.handler.query.impl;
  
  import com.actiontech.dble.backend.mysql.nio.handler.query.BaseDMLHandler;
  import com.actiontech.dble.backend.mysql.nio.handler.util.HandlerTool;
  import com.actiontech.dble.net.Session;
  import com.actiontech.dble.net.mysql.FieldPacket;
  import com.actiontech.dble.net.mysql.RowDataPacket;
  import com.actiontech.dble.net.service.AbstractService;
  import com.actiontech.dble.plan.common.field.Field;
  import com.actiontech.dble.plan.common.item.Item;
  import org.jetbrains.annotations.NotNull;
  
  import java.util.List;
  import java.util.concurrent.locks.ReentrantLock;
  
  public class WhereHandler extends BaseDMLHandler {
  
      public WhereHandler(long id, Session session, Item where) {
          super(id, session);
          assert (where != null);
          this.where = where;
      }
  
      private Item where = null;
      private List<Field> sourceFields;
      // if merge handler have no order by, the row response is not thread safe
      private ReentrantLock lock = new ReentrantLock();
  
      @Override
      public HandlerType type() {
          return HandlerType.WHERE;
      }
  
      @Override
      public void fieldEofResponse(byte[] headerNull, List<byte[]> fieldsNull, final List<FieldPacket> fieldPackets,
                                   byte[] eofNull, boolean isLeft, @NotNull AbstractService service) {
          session.setHandlerStart(this);
          if (terminate.get())
              return;
          this.fieldPackets = fieldPackets;
          this.sourceFields = HandlerTool.createFields(this.fieldPackets);
          nextHandler.fieldEofResponse(null, null, this.fieldPackets, null, this.isLeft, service);
      }
  
      @Override
      public boolean rowResponse(byte[] rowNull, final RowDataPacket rowPacket, boolean isLeft, @NotNull AbstractService service) {
          if (terminate.get())
              return true;
          lock.lock();
          try {
              HandlerTool.initFields(this.sourceFields, rowPacket.fieldValues);
              Item whereItem = HandlerTool.createItem(this.where, this.sourceFields, 0, this.isAllPushDown(), this.type());
              /* use whereto filter */
              if (whereItem.valBool()) {
                  nextHandler.rowResponse(null, rowPacket, this.isLeft, service);
              } else {
                  // nothing
              }
              return false;
          } finally {
              lock.unlock();
          }
      }
  
      @Override
      public void rowEofResponse(byte[] data, boolean isLeft, @NotNull AbstractService service) {
          if (terminate.get())
              return;
          session.setHandlerEnd(this);
          nextHandler.rowEofResponse(data, this.isLeft, service);
      }
  
      @Override
      public void onTerminate() {
      }
  
      @Override
      public ExplainType explainType() {
          return ExplainType.WHERE_FILTER;
      }
  
  }
  