| /** |
| * 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.yarn.sharedcache; |
| |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| |
| import org.apache.hadoop.classification.InterfaceAudience.Public; |
| import org.apache.hadoop.classification.InterfaceStability.Evolving; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.util.ReflectionUtils; |
| import org.apache.hadoop.yarn.conf.YarnConfiguration; |
| import org.apache.hadoop.yarn.exceptions.YarnRuntimeException; |
| |
| @SuppressWarnings("unchecked") |
| @Public |
| @Evolving |
| /** |
| * A factory class for creating checksum objects based on a configurable |
| * algorithm implementation |
| */ |
| public class SharedCacheChecksumFactory { |
| private static final |
| ConcurrentMap<Class<? extends SharedCacheChecksum>,SharedCacheChecksum> |
| instances = |
| new ConcurrentHashMap<Class<? extends SharedCacheChecksum>, |
| SharedCacheChecksum>(); |
| |
| private static final Class<? extends SharedCacheChecksum> defaultAlgorithm; |
| |
| static { |
| try { |
| defaultAlgorithm = (Class<? extends SharedCacheChecksum>) |
| Class.forName( |
| YarnConfiguration.DEFAULT_SHARED_CACHE_CHECKSUM_ALGO_IMPL); |
| } catch (Exception e) { |
| // cannot happen |
| throw new ExceptionInInitializerError(e); |
| } |
| } |
| |
| /** |
| * Get a new <code>SharedCacheChecksum</code> object based on the configurable |
| * algorithm implementation |
| * (see <code>yarn.sharedcache.checksum.algo.impl</code>) |
| * |
| * @return <code>SharedCacheChecksum</code> object |
| */ |
| public static SharedCacheChecksum getChecksum(Configuration conf) { |
| Class<? extends SharedCacheChecksum> clazz = |
| conf.getClass(YarnConfiguration.SHARED_CACHE_CHECKSUM_ALGO_IMPL, |
| defaultAlgorithm, SharedCacheChecksum.class); |
| SharedCacheChecksum checksum = instances.get(clazz); |
| if (checksum == null) { |
| try { |
| checksum = ReflectionUtils.newInstance(clazz, conf); |
| SharedCacheChecksum old = instances.putIfAbsent(clazz, checksum); |
| if (old != null) { |
| checksum = old; |
| } |
| } catch (Exception e) { |
| throw new YarnRuntimeException(e); |
| } |
| } |
| |
| return checksum; |
| } |
| } |