| /* |
| * 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.utils.timerangeiterator; |
| |
| import org.apache.iotdb.tsfile.read.common.TimeRange; |
| |
| /** |
| * This class iteratively generates pre-aggregated time windows. |
| * |
| * <p>For example, startTime = 0, endTime = 11, interval = 5, slidingStep = 3, return |
| * [0,2),[2,3),[3,5),[5,6),[6,8),[8,9),[9,10) |
| */ |
| public class PreAggrWindowIterator implements ITimeRangeIterator { |
| |
| // total query [startTime, endTime) |
| private final long startTime; |
| private final long endTime; |
| private final long interval; |
| private final long slidingStep; |
| |
| private final boolean isAscending; |
| |
| private long curInterval; |
| private long curSlidingStep; |
| private boolean isIntervalCyclicChange = false; |
| private int intervalCnt = 0; |
| |
| private TimeRange curTimeRange; |
| |
| public PreAggrWindowIterator( |
| long startTime, long endTime, long interval, long slidingStep, boolean isAscending) { |
| this.startTime = startTime; |
| this.endTime = endTime; |
| this.interval = interval; |
| this.slidingStep = slidingStep; |
| this.isAscending = isAscending; |
| initIntervalAndStep(); |
| } |
| |
| @Override |
| public TimeRange getFirstTimeRange() { |
| if (isAscending) { |
| return getLeftmostTimeRange(); |
| } else { |
| return getRightmostTimeRange(); |
| } |
| } |
| |
| private TimeRange getLeftmostTimeRange() { |
| long retEndTime = Math.min(startTime + curInterval, endTime); |
| updateIntervalAndStep(); |
| return new TimeRange(startTime, retEndTime); |
| } |
| |
| private TimeRange getRightmostTimeRange() { |
| long retStartTime; |
| long retEndTime; |
| long intervalNum = (long) Math.ceil((endTime - startTime) / (double) slidingStep); |
| retStartTime = slidingStep * (intervalNum - 1) + startTime; |
| if (isIntervalCyclicChange && endTime - retStartTime > interval % slidingStep) { |
| retStartTime += interval % slidingStep; |
| updateIntervalAndStep(); |
| } |
| retEndTime = Math.min(retStartTime + curInterval, endTime); |
| updateIntervalAndStep(); |
| return new TimeRange(retStartTime, retEndTime); |
| } |
| |
| @Override |
| public boolean hasNextTimeRange() { |
| if (curTimeRange == null) { |
| curTimeRange = getFirstTimeRange(); |
| return true; |
| } |
| |
| long retStartTime, retEndTime; |
| long curStartTime = curTimeRange.getMin(); |
| if (isAscending) { |
| retStartTime = curStartTime + curSlidingStep; |
| // This is an open interval , [0-100) |
| if (retStartTime >= endTime) { |
| return false; |
| } |
| } else { |
| retStartTime = curStartTime - curSlidingStep; |
| if (retStartTime < startTime) { |
| return false; |
| } |
| } |
| retEndTime = Math.min(retStartTime + curInterval, endTime); |
| updateIntervalAndStep(); |
| curTimeRange = new TimeRange(retStartTime, retEndTime); |
| return true; |
| } |
| |
| @Override |
| public TimeRange nextTimeRange() { |
| if (curTimeRange != null || hasNextTimeRange()) { |
| return curTimeRange; |
| } |
| return null; |
| } |
| |
| private void initIntervalAndStep() { |
| if (slidingStep >= interval) { |
| curInterval = interval; |
| curSlidingStep = slidingStep; |
| } else if (interval % slidingStep == 0) { |
| curInterval = slidingStep; |
| curSlidingStep = slidingStep; |
| } else { |
| isIntervalCyclicChange = true; |
| curInterval = interval % slidingStep; |
| curSlidingStep = curInterval; |
| } |
| } |
| |
| private void updateIntervalAndStep() { |
| if (!isIntervalCyclicChange) { |
| return; |
| } |
| |
| if (isAscending) { |
| curSlidingStep = curInterval; |
| } |
| intervalCnt++; |
| if ((intervalCnt & 1) == 1) { |
| curInterval = slidingStep - interval % slidingStep; |
| } else { |
| curInterval = interval % slidingStep; |
| } |
| if (!isAscending) { |
| curSlidingStep = curInterval; |
| } |
| } |
| |
| @Override |
| public boolean isAscending() { |
| return isAscending; |
| } |
| } |