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.hcatalog.templeton.tool; import java.io.IOException; import java.util.Date; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hcatalog.templeton.tool.TempletonStorage.Type; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * This does periodic cleanup */ public class HDFSCleanup extends Thread { protected Configuration appConf; // The interval to wake up and check the queue public static final String HDFS_CLEANUP_INTERVAL = "templeton.hdfs.cleanup.interval"; // 12 hours // The max age of a task allowed public static final String HDFS_CLEANUP_MAX_AGE = "templeton.hdfs.cleanup.maxage"; // ~ 1 week protected static long interval = 1000L * 60L * 60L * 12L; protected static long maxage = 1000L * 60L * 60L * 24L * 7L; // The logger private static final Log LOG = LogFactory.getLog(HDFSCleanup.class); // Handle to cancel loop private boolean stop = false; // The instance private static HDFSCleanup thisclass = null; // Whether the cycle is running private static boolean isRunning = false; // The storage root private String storage_root; /** * Create a cleanup object. */ private HDFSCleanup(Configuration appConf) { this.appConf = appConf; interval = appConf.getLong(HDFS_CLEANUP_INTERVAL, interval); maxage = appConf.getLong(HDFS_CLEANUP_MAX_AGE, maxage); storage_root = appConf.get(TempletonStorage.STORAGE_ROOT); } public static HDFSCleanup getInstance(Configuration appConf) { if (thisclass != null) { return thisclass; } thisclass = new HDFSCleanup(appConf); return thisclass; } public static void startInstance(Configuration appConf) throws IOException { if (!isRunning) { getInstance(appConf).start(); } } /** * Run the cleanup loop. * */ public void run() { FileSystem fs = null; while (!stop) { try { // Put each check in a separate try/catch, so if that particular // cycle fails, it'll try again on the next cycle. try { if (fs == null) { fs = FileSystem.get(appConf); } checkFiles(fs); } catch (Exception e) { LOG.error("Cleanup cycle failed: " + e.getMessage()); } long sleepMillis = (long) (Math.random() * interval); LOG.info("Next execution: " + new Date(new Date().getTime() + sleepMillis)); Thread.sleep(sleepMillis); } catch (Exception e) { // If sleep fails, we should exit now before things get worse. isRunning = false; LOG.error("Cleanup failed: " + e.getMessage(), e); } } isRunning = false; } /** * Loop through all the files, deleting any that are older than * maxage. * * @param fs * @throws IOException */ private void checkFiles(FileSystem fs) throws IOException { long now = new Date().getTime(); for (Type type : Type.values()) { try { for (FileStatus status : fs.listStatus(new Path(HDFSStorage.getPath(type, storage_root)))) { if (now - status.getModificationTime() > maxage) { LOG.info("Deleting " + status.getPath().toString()); fs.delete(status.getPath(), true); } } } catch (Exception e) { // Nothing to find for this type. } } } // Handle to stop this process from the outside if needed. public void exit() { stop = true; } }