| /** |
| * 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.distributedlog.feature; |
| |
| import org.apache.distributedlog.DistributedLogConfiguration; |
| import org.apache.bookkeeper.feature.CacheableFeatureProvider; |
| import org.apache.bookkeeper.feature.FeatureProvider; |
| import org.apache.bookkeeper.feature.Feature; |
| import org.apache.bookkeeper.stats.StatsLogger; |
| import org.apache.commons.configuration.ConfigurationException; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.InvocationTargetException; |
| |
| /** |
| * Decider based feature provider |
| */ |
| public abstract class AbstractFeatureProvider<T extends Feature> extends CacheableFeatureProvider<T> { |
| |
| protected static final Logger logger = LoggerFactory.getLogger(AbstractFeatureProvider.class); |
| |
| public static FeatureProvider getFeatureProvider(String rootScope, |
| DistributedLogConfiguration conf, |
| StatsLogger statsLogger) |
| throws IOException { |
| Class<? extends FeatureProvider> featureProviderClass; |
| try { |
| featureProviderClass = conf.getFeatureProviderClass(); |
| } catch (ConfigurationException e) { |
| throw new IOException("Can't initialize the feature provider : ", e); |
| } |
| // create feature provider |
| Constructor<? extends FeatureProvider> constructor; |
| try { |
| constructor = featureProviderClass.getDeclaredConstructor( |
| String.class, |
| DistributedLogConfiguration.class, |
| StatsLogger.class); |
| } catch (NoSuchMethodException e) { |
| throw new IOException("No constructor found for feature provider class " + featureProviderClass + " : ", e); |
| } |
| try { |
| return constructor.newInstance(rootScope, conf, statsLogger); |
| } catch (InstantiationException e) { |
| throw new IOException("Failed to instantiate feature provider : ", e); |
| } catch (IllegalAccessException e) { |
| throw new IOException("Encountered illegal access when instantiating feature provider : ", e); |
| } catch (InvocationTargetException e) { |
| Throwable targetException = e.getTargetException(); |
| if (targetException instanceof IOException) { |
| throw (IOException) targetException; |
| } else { |
| throw new IOException("Encountered invocation target exception while instantiating feature provider : ", e); |
| } |
| } |
| } |
| |
| protected final DistributedLogConfiguration conf; |
| protected final StatsLogger statsLogger; |
| |
| protected AbstractFeatureProvider(String rootScope, |
| DistributedLogConfiguration conf, |
| StatsLogger statsLogger) { |
| super(rootScope); |
| this.conf = conf; |
| this.statsLogger = statsLogger; |
| } |
| |
| /** |
| * Start the feature provider. |
| * |
| * @throws IOException when failed to start the feature provider. |
| */ |
| public void start() throws IOException { |
| // no-op |
| } |
| |
| /** |
| * Stop the feature provider. |
| */ |
| public void stop() { |
| // no-op |
| } |
| |
| } |