| /** |
| * 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.hdfs.server.federation.store.driver.impl; |
| |
| import static org.apache.hadoop.hdfs.server.federation.store.StateStoreUtils.filterMultiple; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.hadoop.hdfs.server.federation.store.StateStoreUtils; |
| import org.apache.hadoop.hdfs.server.federation.store.driver.StateStoreDriver; |
| import org.apache.hadoop.hdfs.server.federation.store.records.BaseRecord; |
| import org.apache.hadoop.hdfs.server.federation.store.records.Query; |
| import org.apache.hadoop.hdfs.server.federation.store.records.QueryResult; |
| |
| /** |
| * Base implementation of a State Store driver. It contains default |
| * implementations for the optional functions. These implementations use an |
| * uncached read/write all algorithm for all changes. In most cases it is |
| * recommended to override the optional functions. |
| * <p> |
| * Drivers may optionally override additional routines for performance |
| * optimization, such as custom get/put/remove queries, depending on the |
| * capabilities of the data store. |
| * <p> |
| */ |
| public abstract class StateStoreBaseImpl extends StateStoreDriver { |
| |
| @Override |
| public <T extends BaseRecord> T get( |
| Class<T> clazz, Query<T> query) throws IOException { |
| List<T> records = getMultiple(clazz, query); |
| if (records.size() > 1) { |
| throw new IOException("Found more than one object in collection"); |
| } else if (records.size() == 1) { |
| return records.get(0); |
| } else { |
| return null; |
| } |
| } |
| |
| @Override |
| public <T extends BaseRecord> List<T> getMultiple( |
| Class<T> clazz, Query<T> query) throws IOException { |
| QueryResult<T> result = get(clazz); |
| List<T> records = result.getRecords(); |
| List<T> ret = filterMultiple(query, records); |
| if (ret == null) { |
| throw new IOException("Cannot fetch records from the store"); |
| } |
| return ret; |
| } |
| |
| @Override |
| public <T extends BaseRecord> boolean put( |
| T record, boolean allowUpdate, boolean errorIfExists) throws IOException { |
| List<T> singletonList = new ArrayList<>(); |
| singletonList.add(record); |
| return putAll(singletonList, allowUpdate, errorIfExists); |
| } |
| |
| @Override |
| public <T extends BaseRecord> boolean remove(T record) throws IOException { |
| final Query<T> query = new Query<T>(record); |
| Class<? extends BaseRecord> clazz = record.getClass(); |
| @SuppressWarnings("unchecked") |
| Class<T> recordClass = (Class<T>)StateStoreUtils.getRecordClass(clazz); |
| return remove(recordClass, query) == 1; |
| } |
| } |