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.pig.backend.hadoop.executionengine.shims; import java.io.IOException; import java.lang.reflect.Method; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.mapred.Counters; import org.apache.hadoop.mapred.DowngradeHelper; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapred.TIPStatus; import org.apache.hadoop.mapred.TaskReport; import org.apache.hadoop.mapred.jobcontrol.Job; import org.apache.hadoop.mapred.jobcontrol.JobControl; import org.apache.hadoop.mapreduce.ContextFactory; import org.apache.hadoop.mapreduce.JobContext; import org.apache.hadoop.mapreduce.JobID; import org.apache.hadoop.mapreduce.OutputCommitter; import org.apache.hadoop.mapreduce.TaskAttemptContext; import org.apache.hadoop.mapreduce.TaskAttemptID; import org.apache.hadoop.mapreduce.TaskType; import org.apache.hadoop.mapreduce.task.JobContextImpl; import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl; import org.apache.pig.PigConfiguration; import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRConfiguration; import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POStore; import org.apache.pig.backend.hadoop23.PigJobControl; public class HadoopShims { private static Log LOG = LogFactory.getLog(HadoopShims.class); private static Method getFileSystemClass; static public JobContext cloneJobContext(JobContext original) throws IOException, InterruptedException { JobContext newContext = ContextFactory.cloneContext(original, new JobConf(original.getConfiguration())); return newContext; } static public TaskAttemptContext createTaskAttemptContext(Configuration conf, TaskAttemptID taskId) { if (conf instanceof JobConf) { return new TaskAttemptContextImpl(new JobConf(conf), taskId); } else { return new TaskAttemptContextImpl(conf, taskId); } } static public JobContext createJobContext(Configuration conf, JobID jobId) { if (conf instanceof JobConf) { return new JobContextImpl(new JobConf(conf), jobId); } else { return new JobContextImpl(conf, jobId); } } static public boolean isMap(TaskAttemptID taskAttemptID) { TaskType type = taskAttemptID.getTaskType(); if (type == TaskType.MAP) return true; return false; } static public TaskAttemptID getNewTaskAttemptID() { TaskAttemptID taskAttemptID = new TaskAttemptID("", 1, TaskType.MAP, 1, 1); return taskAttemptID; } static public TaskAttemptID createTaskAttemptID(String jtIdentifier, int jobId, boolean isMap, int taskId, int id) { if (isMap) { return new TaskAttemptID(jtIdentifier, jobId, TaskType.MAP, taskId, id); } else { return new TaskAttemptID(jtIdentifier, jobId, TaskType.REDUCE, taskId, id); } } static public void storeSchemaForLocal(Job job, POStore st) { // Doing nothing for hadoop 23 } static public String getFsCounterGroupName() { return "org.apache.hadoop.mapreduce.FileSystemCounter"; } static public void commitOrCleanup(OutputCommitter oc, JobContext jc) throws IOException { oc.commitJob(jc); } public static JobControl newJobControl(String groupName, int timeToSleep) { return new PigJobControl(groupName, timeToSleep); } public static long getDefaultBlockSize(FileSystem fs, Path path) { return fs.getDefaultBlockSize(path); } public static Counters getCounters(Job job) throws IOException { try { return new Counters(job.getJob().getCounters()); } catch (Exception ir) { throw new IOException(ir); } } public static boolean isJobFailed(TaskReport report) { return report.getCurrentStatus() == TIPStatus.FAILED; } public static void unsetConf(Configuration conf, String key) { conf.unset(key); } /** * Fetch mode needs to explicitly set the task id which is otherwise done by Hadoop * @param conf * @param taskAttemptID */ public static void setTaskAttemptId(Configuration conf, TaskAttemptID taskAttemptID) { conf.setInt(MRConfiguration.JOB_APPLICATION_ATTEMPT_ID, taskAttemptID.getId()); } /** * Returns whether the give path has a FileSystem implementation. * * @param path path * @param conf configuration * @return true if the give path's scheme has a FileSystem implementation, * false otherwise */ public static boolean hasFileSystemImpl(Path path, Configuration conf) { String scheme = path.toUri().getScheme(); if (scheme != null) { // Hadoop 0.23 if (conf.get("fs.file.impl") != null) { String fsImpl = conf.get("fs." + scheme + ".impl"); if (fsImpl == null) { return false; } } else { // Hadoop 2.x HADOOP-7549 if (getFileSystemClass == null) { try { getFileSystemClass = FileSystem.class.getDeclaredMethod("getFileSystemClass", String.class, Configuration.class); } catch (NoSuchMethodException e) { LOG.warn("Error while trying to determine if path " + path + " has a filesystem implementation"); // Assume has implementation to be safe return true; } } try { Object fs = getFileSystemClass.invoke(null, scheme, conf); return fs == null ? false : true; } catch (Exception e) { return false; } } } return true; } /** * Returns the progress of a Job j which is part of a submitted JobControl * object. The progress is for this Job. So it has to be scaled down by the * num of jobs that are present in the JobControl. * * @param j The Job for which progress is required * @return Returns the percentage progress of this Job * @throws IOException */ public static double progressOfRunningJob(Job j) throws IOException { org.apache.hadoop.mapreduce.Job mrJob = j.getJob(); try { return (mrJob.mapProgress() + mrJob.reduceProgress()) / 2; } catch (Exception ir) { return 0; } } public static void killJob(Job job) throws IOException { org.apache.hadoop.mapreduce.Job mrJob = job.getJob(); try { if (mrJob != null) { mrJob.killJob(); } } catch (Exception ir) { throw new IOException(ir); } } public static TaskReport[] getTaskReports(Job job, TaskType type) throws IOException { if (job.getJobConf().getBoolean(PigConfiguration.PIG_NO_TASK_REPORT, false)) { LOG.info("TaskReports are disabled for job: " + job.getAssignedJobID()); return null; } org.apache.hadoop.mapreduce.Job mrJob = job.getJob(); try { org.apache.hadoop.mapreduce.TaskReport[] reports = mrJob.getTaskReports(type); return DowngradeHelper.downgradeTaskReports(reports); } catch (InterruptedException ir) { throw new IOException(ir); } } public static boolean isHadoopYARN() { return true; } }