CombineFileSplit.java
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上传日期:2018-01-08
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- /**
- * 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.hadoop.mapred.lib;
- import java.io.DataInput;
- import java.io.DataOutput;
- import java.io.IOException;
- import java.util.HashSet;
- import java.util.Set;
- import org.apache.hadoop.fs.FileStatus;
- import org.apache.hadoop.fs.FileSystem;
- import org.apache.hadoop.fs.Path;
- import org.apache.hadoop.fs.BlockLocation;
- import org.apache.hadoop.io.Text;
- import org.apache.hadoop.mapred.InputSplit;
- import org.apache.hadoop.mapred.FileInputFormat;
- import org.apache.hadoop.mapred.JobConf;
- /**
- * A sub-collection of input files. Unlike {@link org.apache.hadoop.mapred.FileSplit},
- * CombineFileSplit * class does not represent a split of a file, but a split of input files
- * into smaller sets. A split may contain blocks from different file but all
- * the blocks in the same split are probably local to some rack <br>
- * CombineFileSplit can be used to implement {@link org.apache.hadoop.mapred.RecordReader}'s,
- * with reading one record per file.
- * @see org.apache.hadoop.mapred.FileSplit
- * @see CombineFileInputFormat
- */
- public class CombineFileSplit implements InputSplit {
- private Path[] paths;
- private long[] startoffset;
- private long[] lengths;
- private String[] locations;
- private long totLength;
- private JobConf job;
- /**
- * default constructor
- */
- public CombineFileSplit() {}
- public CombineFileSplit(JobConf job, Path[] files, long[] start,
- long[] lengths, String[] locations) {
- initSplit(job, files, start, lengths, locations);
- }
- public CombineFileSplit(JobConf job, Path[] files, long[] lengths) {
- long[] startoffset = new long[files.length];
- for (int i = 0; i < startoffset.length; i++) {
- startoffset[i] = 0;
- }
- String[] locations = new String[files.length];
- for (int i = 0; i < locations.length; i++) {
- locations[i] = "";
- }
- initSplit(job, files, startoffset, lengths, locations);
- }
-
- private void initSplit(JobConf job, Path[] files, long[] start,
- long[] lengths, String[] locations) {
- this.job = job;
- this.startoffset = start;
- this.lengths = lengths;
- this.paths = files;
- this.totLength = 0;
- this.locations = locations;
- for(long length : lengths) {
- totLength += length;
- }
- }
- /**
- * Copy constructor
- */
- public CombineFileSplit(CombineFileSplit old) throws IOException {
- this(old.getJob(), old.getPaths(), old.getStartOffsets(),
- old.getLengths(), old.getLocations());
- }
- public JobConf getJob() {
- return job;
- }
- public long getLength() {
- return totLength;
- }
- /** Returns an array containing the startoffsets of the files in the split*/
- public long[] getStartOffsets() {
- return startoffset;
- }
-
- /** Returns an array containing the lengths of the files in the split*/
- public long[] getLengths() {
- return lengths;
- }
- /** Returns the start offset of the i<sup>th</sup> Path */
- public long getOffset(int i) {
- return startoffset[i];
- }
-
- /** Returns the length of the i<sup>th</sup> Path */
- public long getLength(int i) {
- return lengths[i];
- }
-
- /** Returns the number of Paths in the split */
- public int getNumPaths() {
- return paths.length;
- }
- /** Returns the i<sup>th</sup> Path */
- public Path getPath(int i) {
- return paths[i];
- }
-
- /** Returns all the Paths in the split */
- public Path[] getPaths() {
- return paths;
- }
- /** Returns all the Paths where this input-split resides */
- public String[] getLocations() throws IOException {
- return locations;
- }
- public void readFields(DataInput in) throws IOException {
- totLength = in.readLong();
- int arrLength = in.readInt();
- lengths = new long[arrLength];
- for(int i=0; i<arrLength;i++) {
- lengths[i] = in.readLong();
- }
- int filesLength = in.readInt();
- paths = new Path[filesLength];
- for(int i=0; i<filesLength;i++) {
- paths[i] = new Path(Text.readString(in));
- }
- arrLength = in.readInt();
- startoffset = new long[arrLength];
- for(int i=0; i<arrLength;i++) {
- startoffset[i] = in.readLong();
- }
- }
- public void write(DataOutput out) throws IOException {
- out.writeLong(totLength);
- out.writeInt(lengths.length);
- for(long length : lengths) {
- out.writeLong(length);
- }
- out.writeInt(paths.length);
- for(Path p : paths) {
- Text.writeString(out, p.toString());
- }
- out.writeInt(startoffset.length);
- for(long length : startoffset) {
- out.writeLong(length);
- }
- }
-
- @Override
- public String toString() {
- StringBuffer sb = new StringBuffer();
- for (int i = 0; i < paths.length; i++) {
- if (i == 0 ) {
- sb.append("Paths:");
- }
- sb.append(paths[i].toUri().getPath() + ":" + startoffset[i] +
- "+" + lengths[i]);
- if (i < paths.length -1) {
- sb.append(",");
- }
- }
- if (locations != null) {
- String locs = "";
- StringBuffer locsb = new StringBuffer();
- for (int i = 0; i < locations.length; i++) {
- locsb.append(locations[i] + ":");
- }
- locs = locsb.toString();
- sb.append(" Locations:" + locs + "; ");
- }
- return sb.toString();
- }
- }