| /* |
| * 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.transformation.dag.transformer.unary.scalar; |
| |
| import org.apache.iotdb.db.exception.query.QueryProcessException; |
| import org.apache.iotdb.db.queryengine.transformation.api.LayerPointReader; |
| import org.apache.iotdb.db.queryengine.transformation.api.YieldableState; |
| import org.apache.iotdb.db.queryengine.transformation.dag.transformer.unary.UnaryTransformer; |
| |
| import org.apache.tsfile.enums.TSDataType; |
| |
| import java.io.IOException; |
| |
| public class DiffFunctionTransformer extends UnaryTransformer { |
| private final boolean ignoreNull; |
| |
| // cache the last non-null value |
| private double lastValue; |
| |
| // indicate whether lastValue is null |
| private boolean lastValueIsNull = true; |
| |
| public DiffFunctionTransformer(LayerPointReader layerPointReader, boolean ignoreNull) { |
| super(layerPointReader); |
| this.ignoreNull = ignoreNull; |
| } |
| |
| @Override |
| public TSDataType getDataType() { |
| return TSDataType.DOUBLE; |
| } |
| |
| @Override |
| public final YieldableState yieldValue() throws Exception { |
| final YieldableState yieldableState = layerPointReader.yield(); |
| if (!YieldableState.YIELDABLE.equals(yieldableState)) { |
| return yieldableState; |
| } |
| |
| if (!isLayerPointReaderConstant) { |
| cachedTime = layerPointReader.currentTime(); |
| } |
| |
| transformAndCache(); |
| |
| layerPointReader.readyForNext(); |
| return YieldableState.YIELDABLE; |
| } |
| |
| @Override |
| protected void transformAndCache() throws QueryProcessException, IOException { |
| if (layerPointReader.isCurrentNull()) { |
| currentNull = true; // currValue is null, append null |
| |
| // When currValue is null: |
| // ignoreNull = true, keep lastValueIsNull as before |
| // ignoreNull = false, update lastValueIsNull to true |
| lastValueIsNull |= !ignoreNull; |
| } else { |
| double currValue; |
| switch (layerPointReaderDataType) { |
| case INT32: |
| currValue = layerPointReader.currentInt(); |
| break; |
| case INT64: |
| currValue = layerPointReader.currentLong(); |
| break; |
| case FLOAT: |
| currValue = layerPointReader.currentFloat(); |
| break; |
| case DOUBLE: |
| currValue = layerPointReader.currentDouble(); |
| break; |
| default: |
| throw new QueryProcessException( |
| "Unsupported data type: " + layerPointReader.getDataType().toString()); |
| } |
| if (lastValueIsNull) { |
| currentNull = true; // lastValue is null, append null |
| } else { |
| cachedDouble = currValue - lastValue; |
| } |
| |
| lastValue = currValue; // currValue is not null, update lastValue |
| lastValueIsNull = false; |
| } |
| } |
| } |