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.tephra.txprune; import com.google.common.annotations.VisibleForTesting; import com.google.common.util.concurrent.AbstractIdleService; import com.google.common.util.concurrent.ThreadFactoryBuilder; import org.apache.hadoop.conf.Configuration; import org.apache.tephra.TransactionManager; import org.apache.tephra.TxConstants; import org.apache.twill.internal.utils.Instances; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.lang.reflect.InvocationTargetException; import java.util.Arrays; import java.util.HashMap; import java.util.HashSet; import java.util.Map; import java.util.Set; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; /** * Service to prune the invalid list periodically. */ public class TransactionPruningService extends AbstractIdleService { private static final Logger LOG = LoggerFactory.getLogger(TransactionPruningService.class); private final Configuration conf; private final TransactionManager txManager; private final long scheduleInterval; private final boolean pruneEnabled; private TransactionPruningRunnable pruneRunnable; private ScheduledExecutorService scheduledExecutorService; public TransactionPruningService(Configuration conf, TransactionManager txManager) { this.conf = conf; this.txManager = txManager; this.pruneEnabled = conf.getBoolean(TxConstants.TransactionPruning.PRUNE_ENABLE, TxConstants.TransactionPruning.DEFAULT_PRUNE_ENABLE); this.scheduleInterval = conf.getLong(TxConstants.TransactionPruning.PRUNE_INTERVAL, TxConstants.TransactionPruning.DEFAULT_PRUNE_INTERVAL); } @Override protected void startUp() throws Exception { if (!pruneEnabled) { LOG.info("Transaction pruning is not enabled"); return; } LOG.info("Starting {}...", this.getClass().getSimpleName()); scheduledExecutorService = Executors.newSingleThreadScheduledExecutor( new ThreadFactoryBuilder().setNameFormat("tephra-pruning-thread").setDaemon(true).build()); Map<String, TransactionPruningPlugin> plugins = initializePlugins(); long txMaxLifetimeMillis = TimeUnit.SECONDS.toMillis( conf.getInt(TxConstants.Manager.CFG_TX_MAX_LIFETIME, TxConstants.Manager.DEFAULT_TX_MAX_LIFETIME)); long txPruneBufferMillis = TimeUnit.SECONDS .toMillis(conf.getLong(TxConstants.TransactionPruning.PRUNE_GRACE_PERIOD, TxConstants.TransactionPruning.DEFAULT_PRUNE_GRACE_PERIOD)); pruneRunnable = getTxPruneRunnable(txManager, plugins, txMaxLifetimeMillis, txPruneBufferMillis); scheduledExecutorService.scheduleAtFixedRate(pruneRunnable, scheduleInterval, scheduleInterval, TimeUnit.SECONDS); LOG.info("Scheduled {} plugins with interval {} seconds", plugins.size(), scheduleInterval); } @Override protected void shutDown() throws Exception { if (!pruneEnabled) { return; } LOG.info("Stopping {}...", this.getClass().getSimpleName()); try { scheduledExecutorService.shutdown(); scheduledExecutorService.awaitTermination(30, TimeUnit.SECONDS); } catch (InterruptedException e) { scheduledExecutorService.shutdownNow(); Thread.currentThread().interrupt(); } LOG.info("Stopped {}", this.getClass().getSimpleName()); } /** * Trigger a run of the transaction pruning. It will run as soon as no pruning is running. That is, * if pruning is running at this moment, then another will start after it is done. */ public void pruneNow() { if (pruneEnabled) { scheduledExecutorService.execute(pruneRunnable); LOG.info("Triggered invalid transaction pruning due to request received."); } else { LOG.info("Request to trigger transaction pruning received but pruning is not enabled."); } } @VisibleForTesting TransactionPruningRunnable getTxPruneRunnable(TransactionManager txManager, Map<String, TransactionPruningPlugin> plugins, long txMaxLifetimeMillis, long txPruneBufferMillis) { return new TransactionPruningRunnable(txManager, plugins, txMaxLifetimeMillis, txPruneBufferMillis); } private Map<String, TransactionPruningPlugin> initializePlugins() throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException, IOException { Map<String, TransactionPruningPlugin> initializedPlugins = new HashMap<>(); // Read set of plugin names from configuration Set<String> plugins = new HashSet<>(Arrays.asList(conf.getTrimmedStrings( TxConstants.TransactionPruning.PLUGINS, TxConstants.TransactionPruning.DEFAULT_PLUGIN))); LOG.info("Initializing invalid list prune plugins {}", plugins); for (String plugin : plugins) { // Load the class for the plugin // TODO: TEPHRA-205 classloader isolation for plugins Class<? extends TransactionPruningPlugin> clazz = null; if (TxConstants.TransactionPruning.DEFAULT_PLUGIN.equals(plugin)) { Class<?> defaultClass = Class.forName(TxConstants.TransactionPruning.DEFAULT_PLUGIN_CLASS); if (TransactionPruningPlugin.class.isAssignableFrom(defaultClass)) { //noinspection unchecked clazz = (Class<? extends TransactionPruningPlugin>) defaultClass; } } else { clazz = conf.getClass(plugin + TxConstants.TransactionPruning.PLUGIN_CLASS_SUFFIX, null, TransactionPruningPlugin.class); } if (clazz == null) { throw new IllegalStateException( "No class specified in configuration for invalid pruning plugin " + plugin); } LOG.debug("Got class {} for plugin {}", clazz.getName(), plugin); TransactionPruningPlugin instance = Instances.newInstance(clazz); instance.initialize(conf); LOG.debug("Plugin {} initialized", plugin); initializedPlugins.put(plugin, instance); } return initializedPlugins; } }