| /* |
| * 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.iotdb.db.queryengine.plan.planner.plan.node.process; |
| |
| import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanNode; |
| import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanNodeId; |
| import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanNodeType; |
| import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanVisitor; |
| |
| import org.apache.tsfile.utils.ReadWriteIOUtils; |
| |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.util.List; |
| import java.util.Objects; |
| |
| /** LimitNode is used to select top n result. It uses the default order of upstream nodes */ |
| public class LimitNode extends SingleChildProcessNode { |
| |
| private final long limit; |
| |
| public LimitNode(PlanNodeId id, long limit) { |
| super(id); |
| this.limit = limit; |
| } |
| |
| public LimitNode(PlanNodeId id, PlanNode child, long limit) { |
| super(id, child); |
| this.limit = limit; |
| } |
| |
| public long getLimit() { |
| return limit; |
| } |
| |
| @Override |
| public PlanNodeType getType() { |
| return PlanNodeType.LIMIT; |
| } |
| |
| @Override |
| public PlanNode clone() { |
| return new LimitNode(getPlanNodeId(), this.limit); |
| } |
| |
| @Override |
| public List<String> getOutputColumnNames() { |
| return child.getOutputColumnNames(); |
| } |
| |
| @Override |
| public <R, C> R accept(PlanVisitor<R, C> visitor, C context) { |
| return visitor.visitLimit(this, context); |
| } |
| |
| @Override |
| protected void serializeAttributes(ByteBuffer byteBuffer) { |
| PlanNodeType.LIMIT.serialize(byteBuffer); |
| ReadWriteIOUtils.write(limit, byteBuffer); |
| } |
| |
| @Override |
| protected void serializeAttributes(DataOutputStream stream) throws IOException { |
| PlanNodeType.LIMIT.serialize(stream); |
| ReadWriteIOUtils.write(limit, stream); |
| } |
| |
| public static LimitNode deserialize(ByteBuffer byteBuffer) { |
| long limit = ReadWriteIOUtils.readLong(byteBuffer); |
| PlanNodeId planNodeId = PlanNodeId.deserialize(byteBuffer); |
| return new LimitNode(planNodeId, limit); |
| } |
| |
| @Override |
| public String toString() { |
| return "LimitNode-" + this.getPlanNodeId(); |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| if (!super.equals(o)) { |
| return false; |
| } |
| LimitNode that = (LimitNode) o; |
| return limit == that.limit; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(super.hashCode(), limit); |
| } |
| } |