/*
* 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.piggybank.storage;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PositionedReadable;
import org.apache.hadoop.fs.Seekable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputFormat;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.pig.IndexableLoadFunc;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigTextInputFormat;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigTextOutputFormat;
import org.apache.pig.backend.hadoop.executionengine.shims.HadoopShims;
import org.apache.pig.piggybank.storage.IndexedStorage.IndexedStorageInputFormat.IndexedStorageRecordReader;
import org.apache.pig.piggybank.storage.IndexedStorage.IndexedStorageInputFormat.IndexedStorageRecordReader.IndexedStorageRecordReaderComparator;
import org.apache.pig.builtin.PigStorage;
import org.apache.pig.data.DataReaderWriter;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.impl.util.StorageUtil;
import org.apache.pig.data.DataType;
import org.apache.pig.data.DataByteArray;
import org.apache.pig.backend.hadoop.executionengine.shims.HadoopShims;
/**
* <code>IndexedStorage</code> is a form of <code>PigStorage</code> that supports a
* per record seek. <code>IndexedStorage</code> creates a separate (hidden) index file for
* every data file that is written. The format of the index file is:
* <pre>
* | Header |
* | Index Body |
* | Footer |
* </pre>
* The Header contains the list of record indices (field numbers) that represent index keys.
* The Index Body contains a <code>Tuple</code> for each record in the data.
* The fields of the <code>Tuple</code> are:
* <ul>
* <li> The index key(s) <code>Tuple</code> </li>
* <li> The number of records that share this index key. </li>
* <li> Offset into the data file to read the first matching record. </li>
* </ul>
* The Footer contains sequentially:
* <ul>
* <li> The smallest key(s) <code>Tuple</code> in the index. </li>
* <li> The largest key(s) <code>Tuple</code> in the index. </li>
* <li> The offset in bytes to the start of the footer </li>
* </ul>
*
* <code>IndexStorage</code> implements <code>IndexableLoadFunc</code> and
* can be used as the 'right table' in a PIG 'merge' or 'merge-sparse' join.
*
* <code>IndexStorage</code> does not require the data to be globally partitioned & sorted
* by index keys. Each partition (separate index) must be locally sorted.
*
* Also note IndexStorage is a loader to demonstrate "merge-sparse" join.
*/
public class IndexedStorage extends PigStorage implements IndexableLoadFunc {
/**
* Constructs a Pig Storer that uses specified regex as a field delimiter.
* @param delimiter - field delimiter to use
* @param offsetsToIndexKeys - list of offset into Tuple for index keys (comma separated)
*/
public IndexedStorage(String delimiter, String offsetsToIndexKeys) {
super(delimiter);
this.fieldDelimiter = StorageUtil.parseFieldDel(delimiter);
String[] stroffsetsToIndexKeys = offsetsToIndexKeys.split(",");
this.offsetsToIndexKeys = new int[stroffsetsToIndexKeys.length];
for (int i = 0; i < stroffsetsToIndexKeys.length; ++i) {
this.offsetsToIndexKeys[i] = Integer.parseInt(stroffsetsToIndexKeys[i]);
}
}
@Override
public OutputFormat getOutputFormat() {
return new IndexedStorageOutputFormat(fieldDelimiter, offsetsToIndexKeys);
}
/**
* Assumes this list of readers is already sorted except for the provided element.
* This element is bubbled up the array to its appropriate sort location
* (faster than doing a Utils sort).
*/
private void sortReader(int startIndex) {
int idx = startIndex;
while (idx < this.readers.length - 1) {
IndexedStorageRecordReader reader1 = this.readers[idx];
IndexedStorageRecordReader reader2 = this.readers[idx+1];
if (this.readerComparator.compare(reader1, reader2) <= 0) {
return;
}
this.readers[idx] = reader2;
this.readers[idx+1] = reader1;
idx++;
}
}
/**
* Internal OutputFormat class
*/
public static class IndexedStorageOutputFormat extends PigTextOutputFormat {
public IndexedStorageOutputFormat(byte delimiter, int[] offsetsToIndexKeys) {
/* Call the base class constructor */
super(delimiter);
this.fieldDelimiter = delimiter;
this.offsetsToIndexKeys = offsetsToIndexKeys;
}
@Override
public RecordWriter<WritableComparable, Tuple> getRecordWriter(
TaskAttemptContext context) throws IOException,
InterruptedException {
Configuration conf = context.getConfiguration();
FileSystem fs = FileSystem.get(conf);
Path file = this.getDefaultWorkFile(context, "");
FSDataOutputStream fileOut = fs.create(file, false);
IndexManager indexManager = new IndexManager(offsetsToIndexKeys);
indexManager.createIndexFile(fs, file);
return new IndexedStorageRecordWriter(fileOut, this.fieldDelimiter, indexManager);
}
/**
* Internal class to do the actual record writing and index generation
*
*/
public static class IndexedStorageRecordWriter extends PigLineRecordWriter {
public IndexedStorageRecordWriter(FSDataOutputStream fileOut, byte fieldDel, IndexManager indexManager) throws IOException {
super(fileOut, fieldDel);
this.fileOut = fileOut;
this.indexManager = indexManager;
/* Write the index header first */
this.indexManager.WriteIndexHeader();
}
@Override
public void write(WritableComparable key, Tuple value) throws IOException {
/* Write the data */
long offset = this.fileOut.getPos();
super.write(key, value);
/* Build index */
this.indexManager.BuildIndex(value, offset);
}
@Override
public void close(TaskAttemptContext context)
throws IOException {
this.indexManager.WriterIndexFooter();
this.indexManager.Close();
super.close(context);
}
/**
* Output stream for data
*/
private FSDataOutputStream fileOut;
/**
* Index builder
*/
private IndexManager indexManager = null;
}
/**
* Delimiter to use between fields
*/
final private byte fieldDelimiter;
/**
* Offsets to index keys in given tuple
*/
final protected int[] offsetsToIndexKeys;
}
@Override
public InputFormat getInputFormat() {
return new IndexedStorageInputFormat();
}
@Override
public Tuple getNext() throws IOException {
if (this.readers == null) {
return super.getNext();
}
while (currentReaderIndexStart < this.readers.length) {
IndexedStorageRecordReader r = this.readers[currentReaderIndexStart];
this.prepareToRead(r, null);
Tuple tuple = super.getNext();
if (tuple == null) {
currentReaderIndexStart++;
r.close();
continue; //next Reader
}
//if we haven't yet initialized the indexManager (by reading the first index key)
if (r.indexManager.lastIndexKeyTuple == null) {
//initialize the indexManager
if (r.indexManager.ReadIndex() == null) {
//There should never be a case where there is a non-null record - but no corresponding index.
throw new IOException("Missing Index for Tuple: " + tuple);
}
}
r.indexManager.numberOfTuples--;
if (r.indexManager.numberOfTuples == 0) {
if (r.indexManager.ReadIndex() == null) {
r.close();
currentReaderIndexStart++;
} else {
//Since the index of the current reader was increased, we may need to push the
//current reader back in the sorted list of readers.
sortReader(currentReaderIndexStart);
}
}
return tuple;
}
return null;
}
/**
* IndexableLoadFunc interface implementation
*/
@Override
public void initialize(Configuration conf) throws IOException {
try {
InputFormat inputFormat = this.getInputFormat();
TaskAttemptID id = TaskAttemptID.forName(conf.get("mapred.task.id"));
if (System.getenv("HADOOP_TOKEN_FILE_LOCATION") != null) {
conf.set("mapreduce.job.credentials.binary", System.getenv("HADOOP_TOKEN_FILE_LOCATION"));
}
List<FileSplit> fileSplits = inputFormat.getSplits(HadoopShims.createJobContext(conf, null));
this.readers = new IndexedStorageRecordReader[fileSplits.size()];
int idx = 0;
Iterator<FileSplit> it = fileSplits.iterator();
while (it.hasNext()) {
FileSplit fileSplit = it.next();
TaskAttemptContext context = HadoopShims.createTaskAttemptContext(conf, id);
IndexedStorageRecordReader r = (IndexedStorageRecordReader) inputFormat.createRecordReader(fileSplit, context);
r.initialize(fileSplit, context);
this.readers[idx] = r;
idx++;
}
Arrays.sort(this.readers, this.readerComparator);
} catch (InterruptedException e) {
throw new IOException(e);
}
}
@Override
/* The list of readers is always sorted before and after this call. */
public void seekNear(Tuple keys) throws IOException {
/* Keeps track of the last (if any) reader where seekNear was called */
int lastIndexModified = -1;
int idx = currentReaderIndexStart;
while (idx < this.readers.length) {
IndexedStorageRecordReader r = this.readers[idx];
/* The key falls within the range of the reader index */
if (keys.compareTo(r.indexManager.maxIndexKeyTuple) <= 0 && keys.compareTo(r.indexManager.minIndexKeyTuple) >= 0) {
r.seekNear(keys);
lastIndexModified = idx;
/* The key is greater than the current range of the reader index */
} else if (keys.compareTo(r.indexManager.maxIndexKeyTuple) > 0) {
currentReaderIndexStart++;
/* DO NOTHING - The key is less than the current range of the reader index */
} else {
break;
}
idx++;
}
/*
* There is something to sort.
* We can rely on the following invariants that make the following check accurate:
* - currentReaderIndexStart is always >= 0.
* - lastIndexModified is only positive if seekNear was called.
* - lastIndexModified >= currentReaderIndexStart if lastIndexModifed >= 0. This is true because the list
* is already sorted.
*/
if (lastIndexModified - currentReaderIndexStart >= 0) {
/*
* The following logic is optimized for the (common) case where there are a tiny number of readers that
* need to be repositioned relative to the other readers in the much larger sorted list.
*/
/* First, just sort the readers that were updated relative to one another. */
Arrays.sort(this.readers, currentReaderIndexStart, lastIndexModified+1, this.readerComparator);
/* In descending order, push the updated readers back in the the sorted list. */
for (idx = lastIndexModified; idx >= currentReaderIndexStart; idx--) {
sortReader(idx);
}
}
}
@Override
public void close() throws IOException {
for (IndexedStorageRecordReader reader : this.readers) {
reader.close();
}
}
/**
* <code>IndexManager</code> manages the index file (both writing and reading)
* It keeps track of the last index read during reading.
*/
public static class IndexManager {
/**
* Constructor (called during reading)
* @param ifile index file to read
*/
public IndexManager(FileStatus ifile) {
this.indexFile = ifile;
this.offsetToFooter = -1;
}
/**
* Constructor (called during writing)
* @param offsetsToIndexKeys
*/
public IndexManager(int[] offsetsToIndexKeys) {
this.offsetsToIndexKeys = offsetsToIndexKeys;
this.offsetToFooter = -1;
}
/**
* Construct index file path for a given a data file
* @param file - Data file
* @return - Index file path for given data file
*/
private static Path getIndexFileName(Path file) {
return new Path(file.getParent(), "." + file.getName() + ".index");
}
/**
* Open the index file for writing for given data file
* @param fs
* @param file
* @throws IOException
*/
public void createIndexFile(FileSystem fs, Path file) throws IOException {
this.indexOut = fs.create(IndexManager.getIndexFileName(file), false);
}
/**
* Opens the index file.
*/
public void openIndexFile(FileSystem fs) throws IOException {
this.indexIn = fs.open(this.indexFile.getPath());
}
/**
* Close the index file
* @throws IOException
*/
public void Close() throws IOException {
this.indexOut.close();
}
/**
* Build index tuple
*
* @throws IOException
*/
private void BuildIndex(Tuple t, long offset) throws IOException {
/* Build index key tuple */
Tuple indexKeyTuple = tupleFactory.newTuple(this.offsetsToIndexKeys.length);
for (int i = 0; i < this.offsetsToIndexKeys.length; ++i) {
indexKeyTuple.set(i, t.get(this.offsetsToIndexKeys[i]));
}
/* Check if we have already seen Tuple(s) with same index keys */
if (indexKeyTuple.compareTo(this.lastIndexKeyTuple) == 0) {
/* We have seen Tuple(s) with given index keys, update the tuple count */
this.numberOfTuples += 1;
}
else {
if (this.lastIndexKeyTuple != null)
this.WriteIndex();
this.lastIndexKeyTuple = indexKeyTuple;
this.minIndexKeyTuple = ((this.minIndexKeyTuple == null) || (indexKeyTuple.compareTo(this.minIndexKeyTuple) < 0)) ? indexKeyTuple : this.minIndexKeyTuple;
this.maxIndexKeyTuple = ((this.maxIndexKeyTuple == null) || (indexKeyTuple.compareTo(this.maxIndexKeyTuple) > 0)) ? indexKeyTuple : this.maxIndexKeyTuple;
/* New index tuple for newly seen index key */
this.indexTuple = tupleFactory.newTuple(3);
/* Add index keys to index Tuple */
this.indexTuple.set(0, indexKeyTuple);
/* Reset Tuple count for index key */
this.numberOfTuples = 1;
/* Remember offset to Tuple with new index keys */
this.indexTuple.set(2, offset);
}
}
/**
* Write index header
* @param indexOut - Stream to write to
* @param ih - Index header to write
* @throws IOException
*/
public void WriteIndexHeader() throws IOException {
/* Number of index keys */
indexOut.writeInt(this.offsetsToIndexKeys.length);
/* Offset to index keys */
for (int i = 0; i < this.offsetsToIndexKeys.length; ++i) {
indexOut.writeInt(this.offsetsToIndexKeys[i]);
}
}
/**
* Read index header
* @param indexIn - Stream to read from
* @return Index header
* @throws IOException
*/
public void ReadIndexHeader() throws IOException {
/* Number of index keys */
int nkeys = this.indexIn.readInt();
/* Offset to index keys */
this.offsetsToIndexKeys = new int[nkeys];
for (int i = 0; i < nkeys; ++i) {
offsetsToIndexKeys[i] = this.indexIn.readInt();
}
}
/**
* Writes the index footer
*/
public void WriterIndexFooter() throws IOException {
/* Flush indexes for remaining records */
this.WriteIndex();
/* record the offset to footer */
this.offsetToFooter = this.indexOut.getPos();
/* Write index footer */
DataReaderWriter.writeDatum(indexOut, this.minIndexKeyTuple);
DataReaderWriter.writeDatum(indexOut, this.maxIndexKeyTuple);
/* Offset to footer */
indexOut.writeLong(this.offsetToFooter);
}
/**
* Reads the index footer
*/
public void ReadIndexFooter() throws IOException {
long currentOffset = this.indexIn.getPos();
this.SeekToIndexFooter();
this.minIndexKeyTuple = (Tuple)DataReaderWriter.readDatum(this.indexIn);
this.maxIndexKeyTuple = (Tuple)DataReaderWriter.readDatum(this.indexIn);
this.indexIn.seek(currentOffset);
}
/**
* Seeks to the index footer
*/
public void SeekToIndexFooter() throws IOException {
if (this.offsetToFooter < 0) {
/* offset to footer is at last long (8 bytes) in the file */
this.indexIn.seek(this.indexFile.getLen()-8);
this.offsetToFooter = this.indexIn.readLong();
}
this.indexIn.seek(this.offsetToFooter);
}
/**
* Writes the current index.
*/
public void WriteIndex() throws IOException {
this.indexTuple.set(1, this.numberOfTuples);
DataReaderWriter.writeDatum(this.indexOut, this.indexTuple);
}
/**
* Extracts the index key from the index tuple
*/
public Tuple getIndexKeyTuple(Tuple indexTuple) throws IOException {
if (indexTuple.size() == 3)
return (Tuple)indexTuple.get(0);
else
throw new IOException("Invalid index record with size " + indexTuple.size());
}
/**
* Extracts the number of records that share the current key from the index tuple.
*/
public long getIndexKeyTupleCount(Tuple indexTuple) throws IOException {
if (indexTuple.size() == 3)
return (Long)indexTuple.get(1);
else
throw new IOException("Invalid index record with size " + indexTuple.size());
}
/**
* Extracts the offset into the data file from the index tuple.
*/
public long getOffset(Tuple indexTuple) throws IOException {
if (indexTuple.size() == 3)
return (Long)indexTuple.get(2);
else
throw new IOException("Invalid index record with size " + indexTuple.size());
}
/**
* Reads the next index from the index file (or null if EOF) and extracts
* the index fields.
*/
public Tuple ReadIndex() throws IOException {
if (this.indexIn.getPos() < this.offsetToFooter) {
indexTuple = (Tuple)DataReaderWriter.readDatum(this.indexIn);
if (indexTuple != null) {
this.lastIndexKeyTuple = this.getIndexKeyTuple(indexTuple);
this.numberOfTuples = this.getIndexKeyTupleCount(indexTuple);
}
return indexTuple;
}
return null;
}
/**
* Scans the index looking for a given key.
* @return the matching index tuple OR the last index tuple
* greater than the requested key if no match is found.
*/
public Tuple ScanIndex(Tuple keys) throws IOException {
if (lastIndexKeyTuple != null && keys.compareTo(this.lastIndexKeyTuple) <= 0) {
return indexTuple;
}
/* Scan the index looking for given key */
while ((indexTuple = this.ReadIndex()) != null) {
if (keys.compareTo(this.lastIndexKeyTuple) > 0)
continue;
else
break;
}
return indexTuple;
}
/**
* stores the list of record indices that identify keys.
*/
private int[] offsetsToIndexKeys = null;
/**
* offset in bytes to the start of the footer of the index.
*/
private long offsetToFooter = -1;
/**
* output stream when writing the index.
*/
FSDataOutputStream indexOut;
/**
* input stream when reading the index.
*/
FSDataInputStream indexIn;
/**
* Tuple factory to create index tuples
*/
private TupleFactory tupleFactory = TupleFactory.getInstance();
/**
* Index key tuple of the form
* ((Tuple of index keys), count of tuples with index keys, offset to first tuple with index keys)
*/
private Tuple indexTuple = tupleFactory.newTuple(3);
/**
* "Smallest" index key tuple seen
*/
private Tuple minIndexKeyTuple = null;
/**
* "Biggest" index key tuple seen
*/
private Tuple maxIndexKeyTuple = null;
/**
* Last seen index key tuple
*/
private Tuple lastIndexKeyTuple = null;
/**
* Number of tuples seen for a index key
*/
private long numberOfTuples = 0;
/**
* The index file.
*/
private FileStatus indexFile;
}
/**
* Internal InputFormat class
*/
public static class IndexedStorageInputFormat extends PigTextInputFormat {
@Override
public RecordReader<LongWritable, Text> createRecordReader(InputSplit split, TaskAttemptContext context) {
IndexManager im = null;
try {
FileSystem fs = FileSystem.get(context.getConfiguration());
Path indexFile = IndexManager.getIndexFileName(((FileSplit)split).getPath());
im = new IndexManager(fs.getFileStatus(indexFile));
im.openIndexFile(fs);
im.ReadIndexHeader();
im.ReadIndexFooter();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new IndexedStorageRecordReader(im);
}
@Override
public boolean isSplitable(JobContext context, Path filename) {
return false;
}
/**
* Internal RecordReader class
*/
public static class IndexedStorageRecordReader extends RecordReader<LongWritable, Text> {
private long start;
private long pos;
private long end;
private IndexedStorageLineReader in;
private int maxLineLength;
private LongWritable key = null;
private Text value = null;
private IndexManager indexManager = null;
@Override
public String toString() {
return indexManager.minIndexKeyTuple + "|" + indexManager.lastIndexKeyTuple + "|" + indexManager.maxIndexKeyTuple;
}
public IndexedStorageRecordReader(IndexManager im) {
this.indexManager = im;
}
/**
* Class to compare record readers using underlying indexes
*
*/
public static class IndexedStorageRecordReaderComparator implements Comparator<IndexedStorageRecordReader> {
@Override
public int compare(IndexedStorageRecordReader o1, IndexedStorageRecordReader o2) {
Tuple t1 = (o1.indexManager.lastIndexKeyTuple == null) ? o1.indexManager.minIndexKeyTuple : o1.indexManager.lastIndexKeyTuple;
Tuple t2 = (o2.indexManager.lastIndexKeyTuple == null) ? o2.indexManager.minIndexKeyTuple : o2.indexManager.lastIndexKeyTuple;
return t1.compareTo(t2);
}
}
public static class IndexedStorageLineReader {
private static final int DEFAULT_BUFFER_SIZE = 64 * 1024;
private int bufferSize = DEFAULT_BUFFER_SIZE;
private InputStream in;
private byte[] buffer;
// the number of bytes of real data in the buffer
private int bufferLength = 0;
// the current position in the buffer
private int bufferPosn = 0;
private long bufferOffset = 0;
private static final byte CR = '\r';
private static final byte LF = '\n';
/**
* Create a line reader that reads from the given stream using the
* default buffer-size (64k).
* @param in The input stream
* @throws IOException
*/
public IndexedStorageLineReader(InputStream in) {
this(in, DEFAULT_BUFFER_SIZE);
}
/**
* Create a line reader that reads from the given stream using the
* given buffer-size.
* @param in The input stream
* @param bufferSize Size of the read buffer
* @throws IOException
*/
public IndexedStorageLineReader(InputStream in, int bufferSize) {
if( !(in instanceof Seekable) || !(in instanceof PositionedReadable) ) {
throw new IllegalArgumentException(
"In is not an instance of Seekable or PositionedReadable");
}
this.in = in;
this.bufferSize = bufferSize;
this.buffer = new byte[this.bufferSize];
}
/**
* Create a line reader that reads from the given stream using the
* <code>io.file.buffer.size</code> specified in the given
* <code>Configuration</code>.
* @param in input stream
* @param conf configuration
* @throws IOException
*/
public IndexedStorageLineReader(InputStream in, Configuration conf) throws IOException {
this(in, conf.getInt("io.file.buffer.size", DEFAULT_BUFFER_SIZE));
}
/**
* Close the underlying stream.
* @throws IOException
*/
public void close() throws IOException {
in.close();
}
/**
* Read one line from the InputStream into the given Text. A line
* can be terminated by one of the following: '\n' (LF) , '\r' (CR),
* or '\r\n' (CR+LF). EOF also terminates an otherwise unterminated
* line.
*
* @param str the object to store the given line (without newline)
* @param maxLineLength the maximum number of bytes to store into str;
* the rest of the line is silently discarded.
* @param maxBytesToConsume the maximum number of bytes to consume
* in this call. This is only a hint, because if the line cross
* this threshold, we allow it to happen. It can overshoot
* potentially by as much as one buffer length.
*
* @return the number of bytes read including the (longest) newline
* found.
*
* @throws IOException if the underlying stream throws
*/
public int readLine(Text str, int maxLineLength,
int maxBytesToConsume) throws IOException {
/* We're reading data from in, but the head of the stream may be
* already buffered in buffer, so we have several cases:
* 1. No newline characters are in the buffer, so we need to copy
* everything and read another buffer from the stream.
* 2. An unambiguously terminated line is in buffer, so we just
* copy to str.
* 3. Ambiguously terminated line is in buffer, i.e. buffer ends
* in CR. In this case we copy everything up to CR to str, but
* we also need to see what follows CR: if it's LF, then we
* need consume LF as well, so next call to readLine will read
* from after that.
* We use a flag prevCharCR to signal if previous character was CR
* and, if it happens to be at the end of the buffer, delay
* consuming it until we have a chance to look at the char that
* follows.
*/
str.clear();
int txtLength = 0; //tracks str.getLength(), as an optimization
int newlineLength = 0; //length of terminating newline
boolean prevCharCR = false; //true of prev char was CR
long bytesConsumed = 0;
do {
int startPosn = bufferPosn; //starting from where we left off the last time
if (bufferPosn >= bufferLength) {
startPosn = bufferPosn = 0;
if (prevCharCR)
++bytesConsumed; //account for CR from previous read
bufferOffset = ((Seekable)in).getPos();
bufferLength = in.read(buffer);
if (bufferLength <= 0)
break; // EOF
}
for (; bufferPosn < bufferLength; ++bufferPosn) { //search for newline
if (buffer[bufferPosn] == LF) {
newlineLength = (prevCharCR) ? 2 : 1;
++bufferPosn; // at next invocation proceed from following byte
break;
}
if (prevCharCR) { //CR + notLF, we are at notLF
newlineLength = 1;
break;
}
prevCharCR = (buffer[bufferPosn] == CR);
}
int readLength = bufferPosn - startPosn;
if (prevCharCR && newlineLength == 0)
--readLength; //CR at the end of the buffer
bytesConsumed += readLength;
int appendLength = readLength - newlineLength;
if (appendLength > maxLineLength - txtLength) {
appendLength = maxLineLength - txtLength;
}
if (appendLength > 0) {
str.append(buffer, startPosn, appendLength);
txtLength += appendLength;
}
} while (newlineLength == 0 && bytesConsumed < maxBytesToConsume);
if (bytesConsumed > (long)Integer.MAX_VALUE)
throw new IOException("Too many bytes before newline: " + bytesConsumed);
return (int)bytesConsumed;
}
/**
* Read from the InputStream into the given Text.
* @param str the object to store the given line
* @param maxLineLength the maximum number of bytes to store into str.
* @return the number of bytes read including the newline
* @throws IOException if the underlying stream throws
*/
public int readLine(Text str, int maxLineLength) throws IOException {
return readLine(str, maxLineLength, Integer.MAX_VALUE);
}
/**
* Read from the InputStream into the given Text.
* @param str the object to store the given line
* @return the number of bytes read including the newline
* @throws IOException if the underlying stream throws
*/
public int readLine(Text str) throws IOException {
return readLine(str, Integer.MAX_VALUE, Integer.MAX_VALUE);
}
/**
* If given offset is within the buffer, adjust the buffer position to read from
* otherwise seek to the given offset from start of the file.
* @param offset
* @throws IOException
*/
public void seek(long offset) throws IOException {
if ((offset >= bufferOffset) && (offset < (bufferOffset + bufferLength)))
bufferPosn = (int) (offset - bufferOffset);
else {
bufferPosn = bufferLength;
((Seekable)in).seek(offset);
}
}
}
@Override
public void initialize(InputSplit genericSplit, TaskAttemptContext context)
throws IOException, InterruptedException {
FileSplit split = (FileSplit) genericSplit;
Configuration job = context.getConfiguration();
this.maxLineLength = job.getInt("mapred.linerecordreader.maxlength", Integer.MAX_VALUE);
start = split.getStart();
end = start + split.getLength();
final Path file = split.getPath();
FileSystem fs = file.getFileSystem(job);
FSDataInputStream fileIn = fs.open(split.getPath());
boolean skipFirstLine = false;
if (start != 0) {
skipFirstLine = true;
--start;
fileIn.seek(start);
}
in = new IndexedStorageLineReader(fileIn, job);
if (skipFirstLine) {
start += in.readLine(new Text(), 0, (int)Math.min((long)Integer.MAX_VALUE, end - start));
}
this.pos = start;
}
public void seek(long offset) throws IOException {
in.seek(offset);
pos = offset;
}
/**
* Scan the index for given key and seek to appropriate offset in the data
* @param keys to look for
* @return true if the given key was found, false otherwise
* @throws IOException
*/
public boolean seekNear(Tuple keys) throws IOException {
boolean ret = false;
Tuple indexTuple = this.indexManager.ScanIndex(keys);
if (indexTuple != null) {
long offset = this.indexManager.getOffset(indexTuple) ;
in.seek(offset);
if (keys.compareTo(this.indexManager.getIndexKeyTuple(indexTuple)) == 0) {
ret = true;
}
}
return ret;
}
@Override
public boolean nextKeyValue() throws IOException,
InterruptedException {
if (key == null) {
key = new LongWritable();
}
key.set(pos);
if (value == null) {
value = new Text();
}
int newSize = 0;
while (pos < end) {
newSize = in.readLine(value, maxLineLength,
Math.max((int)Math.min(Integer.MAX_VALUE, end-pos),
maxLineLength));
if (newSize == 0) {
break;
}
pos += newSize;
if (newSize < maxLineLength) {
break;
}
}
if (newSize == 0) {
key = null;
value = null;
return false;
} else {
return true;
}
}
@Override
public LongWritable getCurrentKey() throws IOException,
InterruptedException {
return key;
}
@Override
public Text getCurrentValue() throws IOException,
InterruptedException {
return value;
}
@Override
public float getProgress() throws IOException, InterruptedException {
if (start == end) {
return 0.0f;
} else {
return Math.min(1.0f, (pos - start) / (float)(end - start));
}
}
@Override
public void close() throws IOException {
if (in != null) {
in.close();
}
}
}
}
/**
* List of record readers.
*/
protected IndexedStorageRecordReader[] readers = null;
/**
* Index into the the list of readers to the current reader.
* Readers before this index have been fully scanned for keys.
*/
protected int currentReaderIndexStart = 0;
/**
* Delimiter to use between fields
*/
protected byte fieldDelimiter = '\t';
/**
* Offsets to index keys in tuple
*/
final protected int[] offsetsToIndexKeys;
/**
* Comparator used to compare key tuples.
*/
protected Comparator<IndexedStorageRecordReader> readerComparator = new IndexedStorageInputFormat.IndexedStorageRecordReader.IndexedStorageRecordReaderComparator();
}