| /** |
| * Copyright The Apache Software Foundation |
| * |
| * 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.hadoop.hbase.regionserver; |
| |
| import java.io.IOException; |
| import java.util.List; |
| import java.util.NavigableSet; |
| |
| import org.apache.hadoop.hbase.classification.InterfaceAudience; |
| import org.apache.hadoop.hbase.Cell; |
| import org.apache.hadoop.hbase.CellComparator; |
| import org.apache.hadoop.hbase.CellUtil; |
| import org.apache.hadoop.hbase.HConstants; |
| import org.apache.hadoop.hbase.client.Scan; |
| |
| /** |
| * ReversedStoreScanner extends from StoreScanner, and is used to support |
| * reversed scanning. |
| */ |
| @InterfaceAudience.Private |
| class ReversedStoreScanner extends StoreScanner implements KeyValueScanner { |
| |
| /** |
| * Opens a scanner across memstore, snapshot, and all StoreFiles. Assumes we |
| * are not in a compaction. |
| * |
| * @param store who we scan |
| * @param scanInfo |
| * @param scan the spec |
| * @param columns which columns we are scanning |
| * @throws IOException |
| */ |
| ReversedStoreScanner(Store store, ScanInfo scanInfo, Scan scan, |
| NavigableSet<byte[]> columns, long readPt) |
| throws IOException { |
| super(store, scanInfo, scan, columns, readPt); |
| } |
| |
| /** Constructor for testing. */ |
| ReversedStoreScanner(final Scan scan, ScanInfo scanInfo, ScanType scanType, |
| final NavigableSet<byte[]> columns, final List<KeyValueScanner> scanners) |
| throws IOException { |
| super(scan, scanInfo, scanType, columns, scanners, |
| HConstants.LATEST_TIMESTAMP); |
| } |
| |
| @Override |
| protected void resetKVHeap(List<? extends KeyValueScanner> scanners, |
| CellComparator comparator) throws IOException { |
| // Combine all seeked scanners with a heap |
| heap = new ReversedKeyValueHeap(scanners, comparator); |
| } |
| |
| @Override |
| protected void seekScanners(List<? extends KeyValueScanner> scanners, |
| Cell seekKey, boolean isLazy, boolean isParallelSeek) |
| throws IOException { |
| // Seek all scanners to the start of the Row (or if the exact matching row |
| // key does not exist, then to the start of the previous matching Row). |
| if (CellUtil.matchingRow(seekKey, HConstants.EMPTY_START_ROW)) { |
| for (KeyValueScanner scanner : scanners) { |
| scanner.seekToLastRow(); |
| } |
| } else { |
| for (KeyValueScanner scanner : scanners) { |
| scanner.backwardSeek(seekKey); |
| } |
| } |
| } |
| |
| @Override |
| protected boolean seekToNextRow(Cell kv) throws IOException { |
| return seekToPreviousRow(kv); |
| } |
| |
| /** |
| * Do a backwardSeek in a reversed StoreScanner(scan backward) |
| */ |
| @Override |
| protected boolean seekAsDirection(Cell kv) throws IOException { |
| return backwardSeek(kv); |
| } |
| |
| @Override |
| protected void checkScanOrder(Cell prevKV, Cell kv, |
| CellComparator comparator) throws IOException { |
| // Check that the heap gives us KVs in an increasing order for same row and |
| // decreasing order for different rows. |
| assert prevKV == null || comparator == null || comparator.compareRows(kv, prevKV) < 0 |
| || (CellUtil.matchingRows(kv, prevKV) && comparator.compare(kv, |
| prevKV) >= 0) : "Key " + prevKV |
| + " followed by a " + "error order key " + kv + " in cf " + store |
| + " in reversed scan"; |
| } |
| |
| @Override |
| public boolean reseek(Cell kv) throws IOException { |
| throw new IllegalStateException( |
| "reseek cannot be called on ReversedStoreScanner"); |
| } |
| |
| @Override |
| public boolean seek(Cell key) throws IOException { |
| throw new IllegalStateException( |
| "seek cannot be called on ReversedStoreScanner"); |
| } |
| |
| @Override |
| public boolean seekToPreviousRow(Cell key) throws IOException { |
| boolean flushed = checkFlushed(); |
| checkReseek(flushed); |
| return this.heap.seekToPreviousRow(key); |
| } |
| |
| @Override |
| public boolean backwardSeek(Cell key) throws IOException { |
| boolean flushed = checkFlushed(); |
| checkReseek(flushed); |
| return this.heap.backwardSeek(key); |
| } |
| } |