001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase; 019 020import java.io.IOException; 021import java.util.Map; 022 023import org.apache.yetus.audience.InterfaceAudience; 024import org.apache.hadoop.hbase.client.TableDescriptor; 025 026/** 027 * Get, remove and modify table descriptors. 028 */ 029@InterfaceAudience.Private 030public interface TableDescriptors { 031 032 /** 033 * Test whether a given table exists, i.e, has a table descriptor. 034 */ 035 default boolean exists(TableName tableName) throws IOException { 036 return get(tableName) != null; 037 } 038 039 /** 040 * @return TableDescriptor for tablename 041 */ 042 TableDescriptor get(TableName tableName) throws IOException; 043 044 /** 045 * Get Map of all NamespaceDescriptors for a given namespace. 046 * @return Map of all descriptors. 047 */ 048 Map<String, TableDescriptor> getByNamespace(String name) throws IOException; 049 050 /** 051 * Get Map of all TableDescriptors. Populates the descriptor cache as a side effect. 052 * </p> 053 * Notice: the key of map is the table name which contains namespace. It was generated by 054 * {@link TableName#getNameWithNamespaceInclAsString()}. 055 * @return Map of all descriptors. 056 */ 057 Map<String, TableDescriptor> getAll() throws IOException; 058 059 /** 060 * Add or update descriptor. Just call {@link #update(TableDescriptor, boolean)} with 061 * {@code cacheOnly} as {@code false}. 062 */ 063 default void update(TableDescriptor htd) throws IOException { 064 update(htd, false); 065 } 066 067 /** 068 * Add or update descriptor 069 * @param htd Descriptor to set into TableDescriptors 070 * @param cacheOnly only add the given {@code htd} to cache, without updating the storage. For 071 * example, when creating table, we will write the descriptor to fs when creating the fs 072 * layout, so we do not need to update the fs again. 073 */ 074 void update(TableDescriptor htd, boolean cacheOnly) throws IOException; 075 076 /** 077 * @return Instance of table descriptor or null if none found. 078 */ 079 TableDescriptor remove(TableName tablename) throws IOException; 080}