Java tutorial
/* * 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.phoenix.log; import java.io.Closeable; import java.io.IOException; import java.sql.SQLException; import java.util.concurrent.Executors; import java.util.concurrent.ThreadFactory; import java.util.concurrent.TimeUnit; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.phoenix.query.QueryServices; import com.google.common.util.concurrent.ThreadFactoryBuilder; import com.lmax.disruptor.BlockingWaitStrategy; import com.lmax.disruptor.EventTranslator; import com.lmax.disruptor.ExceptionHandler; import com.lmax.disruptor.TimeoutException; import com.lmax.disruptor.WaitStrategy; import com.lmax.disruptor.dsl.Disruptor; import com.lmax.disruptor.dsl.ProducerType; public class QueryLoggerDisruptor implements Closeable { private volatile Disruptor<RingBufferEvent> disruptor; private boolean isClosed = false; //number of elements to create within the ring buffer. private static final int RING_BUFFER_SIZE = 8 * 1024; private static final Log LOG = LogFactory.getLog(QueryLoggerDisruptor.class); private static final String DEFAULT_WAIT_STRATEGY = BlockingWaitStrategy.class.getName(); public QueryLoggerDisruptor(Configuration configuration) throws SQLException { WaitStrategy waitStrategy; try { waitStrategy = (WaitStrategy) Class .forName(configuration.get(QueryServices.LOG_BUFFER_WAIT_STRATEGY, DEFAULT_WAIT_STRATEGY)) .newInstance(); } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) { throw new SQLException(e); } ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat("QueryLogger" + "-thread-%s") .setDaemon(true).setThreadFactory(new ThreadFactory() { @Override public Thread newThread(Runnable r) { final Thread result = Executors.defaultThreadFactory().newThread(r); result.setContextClassLoader(QueryLoggerDisruptor.class.getClass().getClassLoader()); return result; } }).build(); disruptor = new Disruptor<RingBufferEvent>(RingBufferEvent.FACTORY, configuration.getInt(QueryServices.LOG_BUFFER_SIZE, RING_BUFFER_SIZE), threadFactory, ProducerType.MULTI, waitStrategy); final ExceptionHandler<RingBufferEvent> errorHandler = new QueryLoggerDefaultExceptionHandler(); disruptor.setDefaultExceptionHandler(errorHandler); final QueryLogDetailsEventHandler[] handlers = { new QueryLogDetailsEventHandler(configuration) }; disruptor.handleEventsWith(handlers); LOG.info("Starting QueryLoggerDisruptor for with ringbufferSize=" + disruptor.getRingBuffer().getBufferSize() + ", waitStrategy=" + waitStrategy.getClass().getSimpleName() + ", " + "exceptionHandler=" + errorHandler + "..."); disruptor.start(); } /** * Attempts to publish an event by translating (write) data representations into events claimed from the RingBuffer. * @param translator * @return */ public boolean tryPublish(final EventTranslator<RingBufferEvent> translator) { if (isClosed()) { return false; } return disruptor.getRingBuffer().tryPublishEvent(translator); } public boolean isClosed() { return isClosed; } @Override public void close() throws IOException { isClosed = true; LOG.info("Shutting down QueryLoggerDisruptor.."); try { //we can wait for 2 seconds, so that backlog can be committed disruptor.shutdown(2, TimeUnit.SECONDS); } catch (TimeoutException e) { throw new IOException(e); } } }