| /* |
| * 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.tsfile.read.reader.series; |
| |
| import org.apache.iotdb.tsfile.read.common.block.TsBlock; |
| |
| public class PaginationController { |
| |
| public static final PaginationController UNLIMITED_PAGINATION_CONTROLLER = |
| new PaginationController(0L, 0L); |
| |
| private final boolean hasLimit; |
| |
| private long curLimit; |
| private long curOffset; |
| |
| public PaginationController(long limit, long offset) { |
| // row limit for result set. The default value is 0, which means no limit |
| this.curLimit = limit; |
| this.hasLimit = limit > 0; |
| |
| // row offset for result set. The default value is 0 |
| this.curOffset = offset; |
| } |
| |
| public boolean hasCurOffset() { |
| return curOffset > 0; |
| } |
| |
| public boolean hasCurOffset(long rowCount) { |
| return curOffset >= rowCount; |
| } |
| |
| public boolean hasCurLimit() { |
| return !hasLimit || curLimit > 0; |
| } |
| |
| public void consumeOffset(long rowCount) { |
| curOffset -= rowCount; |
| } |
| |
| public void consumeOffset() { |
| curOffset--; |
| } |
| |
| public long getCurOffset() { |
| return curOffset; |
| } |
| |
| public long getCurLimit() { |
| return curLimit; |
| } |
| |
| public void consumeLimit() { |
| if (hasLimit) { |
| curLimit--; |
| } |
| } |
| |
| public void consumeLimit(long rowCount) { |
| if (hasLimit) { |
| curLimit -= rowCount; |
| } |
| } |
| |
| public TsBlock applyTsBlock(TsBlock resultTsBlock) { |
| int fromIndex = 0; |
| int length = resultTsBlock.getPositionCount(); |
| if (hasCurOffset()) { |
| fromIndex = (int) Math.min(curOffset, length); |
| length -= fromIndex; |
| consumeOffset(fromIndex); |
| } |
| if (hasLimit && curLimit > 0) { |
| length = (int) Math.min(curLimit, length); |
| consumeLimit(length); |
| } |
| return resultTsBlock.getRegion(fromIndex, length); |
| } |
| } |