Java tutorial
package org.apache.rya.accumulo.mr; /* * 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. */ import java.io.IOException; import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Map; import org.apache.accumulo.core.client.Connector; import org.apache.accumulo.core.client.Instance; import org.apache.accumulo.core.client.Scanner; import org.apache.accumulo.core.client.admin.TableOperations; import org.apache.accumulo.core.client.security.tokens.AuthenticationToken; import org.apache.accumulo.core.data.ByteSequence; import org.apache.accumulo.core.data.Key; import org.apache.accumulo.core.data.Range; import org.apache.accumulo.core.data.Value; import org.apache.accumulo.core.file.FileSKVIterator; import org.apache.accumulo.core.file.rfile.RFileOperations; import org.apache.accumulo.core.security.Authorizations; import org.apache.accumulo.core.util.ArgumentChecker; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.BlockLocation; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.InputSplit; import org.apache.hadoop.mapreduce.JobContext; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.RecordReader; import org.apache.hadoop.mapreduce.TaskAttemptContext; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.FileSplit; /** * {@link FileInputFormat} that finds the Accumulo tablet files on the HDFS * disk, and uses that as the input for MapReduce jobs. */ public class AccumuloHDFSFileInputFormat extends FileInputFormat<Key, Value> { public static final Range ALLRANGE = new Range(new Text("\u0000"), new Text("\uFFFD")); @Override public List<InputSplit> getSplits(JobContext jobContext) throws IOException { //read the params from AccumuloInputFormat Configuration conf = jobContext.getConfiguration(); Instance instance = MRUtils.AccumuloProps.getInstance(jobContext); String user = MRUtils.AccumuloProps.getUsername(jobContext); AuthenticationToken password = MRUtils.AccumuloProps.getPassword(jobContext); String table = MRUtils.AccumuloProps.getTablename(jobContext); ArgumentChecker.notNull(instance); ArgumentChecker.notNull(table); //find the files necessary try { Connector connector = instance.getConnector(user, password); TableOperations tos = connector.tableOperations(); String tableId = tos.tableIdMap().get(table); Scanner scanner = connector.createScanner("accumulo.metadata", Authorizations.EMPTY); //TODO: auths? scanner.setRange(new Range(new Text(tableId + "\u0000"), new Text(tableId + "\uFFFD"))); scanner.fetchColumnFamily(new Text("file")); List<String> files = new ArrayList<String>(); List<InputSplit> fileSplits = new ArrayList<InputSplit>(); for (Map.Entry<Key, Value> entry : scanner) { String file = entry.getKey().getColumnQualifier().toString(); Path path = new Path(file); FileSystem fs = path.getFileSystem(conf); FileStatus fileStatus = fs.getFileStatus(path); long len = fileStatus.getLen(); BlockLocation[] fileBlockLocations = fs.getFileBlockLocations(fileStatus, 0, len); files.add(file); fileSplits.add(new FileSplit(path, 0, len, fileBlockLocations[0].getHosts())); } System.out.println(files); return fileSplits; } catch (Exception e) { throw new IOException(e); } } @Override public RecordReader<Key, Value> createRecordReader(InputSplit inputSplit, TaskAttemptContext taskAttemptContext) throws IOException, InterruptedException { return new RecordReader<Key, Value>() { private FileSKVIterator fileSKVIterator; private boolean started = false; @Override public void initialize(InputSplit inputSplit, TaskAttemptContext taskAttemptContext) throws IOException, InterruptedException { FileSplit split = (FileSplit) inputSplit; Configuration job = taskAttemptContext.getConfiguration(); Path file = split.getPath(); FileSystem fs = file.getFileSystem(job); Instance instance = MRUtils.AccumuloProps.getInstance(taskAttemptContext); fileSKVIterator = RFileOperations.getInstance().openReader(file.toString(), ALLRANGE, new HashSet<ByteSequence>(), false, fs, job, instance.getConfiguration()); } @Override public boolean nextKeyValue() throws IOException, InterruptedException { if (started) { fileSKVIterator.next(); } else { started = true; // don't move past the first record yet } return fileSKVIterator.hasTop(); } @Override public Key getCurrentKey() throws IOException, InterruptedException { return fileSKVIterator.getTopKey(); } @Override public Value getCurrentValue() throws IOException, InterruptedException { return fileSKVIterator.getTopValue(); } @Override public float getProgress() throws IOException, InterruptedException { return 0; } @Override public void close() throws IOException { } }; } /** * Mapper that has no effect. */ @SuppressWarnings("rawtypes") public static class NullMapper extends Mapper { @Override protected void map(Object key, Object value, Context context) throws IOException, InterruptedException { } } }