| /** |
| * |
| * 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.querymatcher; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.hbase.Cell; |
| import org.apache.hadoop.hbase.classification.InterfaceAudience; |
| import org.apache.hadoop.hbase.regionserver.querymatcher.ScanQueryMatcher.MatchCode; |
| |
| /** |
| * Implementing classes of this interface will be used for the tracking |
| * and enforcement of columns and numbers of versions and timeToLive during |
| * the course of a Get or Scan operation. |
| * <p> |
| * Currently there are two different types of Store/Family-level queries. |
| * <ul><li>{@link ExplicitColumnTracker} is used when the query specifies |
| * one or more column qualifiers to return in the family.</li> |
| * <li>{@link ScanWildcardColumnTracker} is used when no columns are |
| * explicitly specified.</li> |
| * </ul> |
| * <p> |
| * This class is utilized by {@link ScanQueryMatcher} mainly through two methods: |
| * <ul><li>{@link #checkColumn} is called when a Put satisfies all other |
| * conditions of the query.</li> |
| * <li>{@link #getNextRowOrNextColumn} is called whenever ScanQueryMatcher |
| * believes that the current column should be skipped (by timestamp, filter etc.)</li> |
| * </ul> |
| * <p> |
| * These two methods returns a |
| * {@link org.apache.hadoop.hbase.regionserver.querymatcher.ScanQueryMatcher.MatchCode} |
| * to define what action should be taken. |
| * <p> |
| * This class is NOT thread-safe as queries are never multi-threaded |
| */ |
| @InterfaceAudience.Private |
| public interface ColumnTracker { |
| |
| /** |
| * Checks if the column is present in the list of requested columns by returning the match code |
| * instance. It does not check against the number of versions for the columns asked for. To do the |
| * version check, one has to call {@link #checkVersions(Cell, long, byte, boolean)} |
| * method based on the return type (INCLUDE) of this method. The values that can be returned by |
| * this method are {@link MatchCode#INCLUDE}, {@link MatchCode#SEEK_NEXT_COL} and |
| * {@link MatchCode#SEEK_NEXT_ROW}. |
| * @param cell |
| * @param type The type of the KeyValue |
| * @return The match code instance. |
| * @throws IOException in case there is an internal consistency problem caused by a data |
| * corruption. |
| */ |
| ScanQueryMatcher.MatchCode checkColumn(Cell cell, byte type) throws IOException; |
| |
| /** |
| * Keeps track of the number of versions for the columns asked for. It assumes that the user has |
| * already checked if the keyvalue needs to be included by calling the |
| * {@link #checkColumn(Cell, byte)} method. The enum values returned by this method |
| * are {@link MatchCode#SKIP}, {@link MatchCode#INCLUDE}, |
| * {@link MatchCode#INCLUDE_AND_SEEK_NEXT_COL} and {@link MatchCode#INCLUDE_AND_SEEK_NEXT_ROW}. |
| * Implementations which include all the columns could just return {@link MatchCode#INCLUDE} in |
| * the {@link #checkColumn(Cell, byte)} method and perform all the operations in this |
| * checkVersions method. |
| * @param cell |
| * @param ttl The timeToLive to enforce. |
| * @param type the type of the key value (Put/Delete) |
| * @param ignoreCount indicates if the KV needs to be excluded while counting (used during |
| * compactions. We only count KV's that are older than all the scanners' read points.) |
| * @return the scan query matcher match code instance |
| * @throws IOException in case there is an internal consistency problem caused by a data |
| * corruption. |
| */ |
| ScanQueryMatcher.MatchCode checkVersions(Cell cell, long ttl, byte type, boolean ignoreCount) |
| throws IOException; |
| /** |
| * Resets the Matcher |
| */ |
| void reset(); |
| |
| /** |
| * |
| * @return <code>true</code> when done. |
| */ |
| boolean done(); |
| |
| /** |
| * Used by matcher and scan/get to get a hint of the next column |
| * to seek to after checkColumn() returns SKIP. Returns the next interesting |
| * column we want, or NULL there is none (wildcard scanner). |
| * |
| * Implementations aren't required to return anything useful unless the most recent |
| * call was to checkColumn() and the return code was SKIP. This is pretty implementation |
| * detail-y, but optimizations are like that. |
| * |
| * @return null, or a ColumnCount that we should seek to |
| */ |
| ColumnCount getColumnHint(); |
| |
| /** |
| * Retrieve the MatchCode for the next row or column |
| * @param cell |
| */ |
| MatchCode getNextRowOrNextColumn(Cell cell); |
| |
| /** |
| * Give the tracker a chance to declare it's done based on only the timestamp |
| * to allow an early out. |
| * |
| * @param timestamp |
| * @return <code>true</code> to early out based on timestamp. |
| */ |
| boolean isDone(long timestamp); |
| } |