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HADOOP-6218. Adds a feature where TFile can be split by Record Sequeunce number. Contributed by Hong Tang and Raghu Angadi.

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git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@824516 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Devaraj Das 2009-10-12 22:07:17 +00:00
parent d3c314e450
commit fed32afd17
6 changed files with 225 additions and 13 deletions
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3
CHANGES.txt
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@ -10,6 +10,9 @@ Trunk (unreleased changes)
hadoop-config.sh so that it allows setting java command options for
JAVA_PLATFORM. (Koji Noguchi via szetszwo)
HADOOP-6218. Adds a feature where TFile can be split by Record
Sequence number. (Hong Tang and Raghu Angadi via ddas)
IMPROVEMENTS
HADOOP-6283. Improve the exception messages thrown by

136
src/java/org/apache/hadoop/io/file/tfile/TFile.java
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@ -669,10 +669,10 @@ void finishDataBlock(boolean bForceFinish) throws IOException {
* TFile Reader. Users may only read TFiles by creating TFile.Reader.Scanner.
* objects. A scanner may scan the whole TFile ({@link Reader#createScanner()}
* ) , a portion of TFile based on byte offsets (
* {@link Reader#createScanner(long, long)}), or a portion of TFile with keys
* {@link Reader#createScannerByByteRange(long, long)}), or a portion of TFile with keys
* fall in a certain key range (for sorted TFile only,
* {@link Reader#createScanner(byte[], byte[])} or
* {@link Reader#createScanner(RawComparable, RawComparable)}).
* {@link Reader#createScannerByKey(byte[], byte[])} or
* {@link Reader#createScannerByKey(RawComparable, RawComparable)}).
*/
public static class Reader implements Closeable {
// The underlying BCFile reader.
@ -986,6 +986,16 @@ Location getBlockContainsKey(RawComparable key, boolean greater)
return new Location(blkIndex, 0);
}
Location getLocationByRecordNum(long recNum) throws IOException {
checkTFileDataIndex();
return tfileIndex.getLocationByRecordNum(recNum);
}
long getRecordNumByLocation(Location location) throws IOException {
checkTFileDataIndex();
return tfileIndex.getRecordNumByLocation(location);
}
int compareKeys(byte[] a, int o1, int l1, byte[] b, int o2, int l2) {
if (!isSorted()) {
throw new RuntimeException("Cannot compare keys for unsorted TFiles.");
@ -1016,6 +1026,21 @@ Location getLocationNear(long offset) {
return new Location(blockIndex, 0);
}
/**
* Get the RecordNum for the first key-value pair in a compressed block
* whose byte offset in the TFile is greater than or equal to the specified
* offset.
*
* @param offset
* the user supplied offset.
* @return the RecordNum to the corresponding entry. If no such entry
* exists, it returns the total entry count.
* @throws IOException
*/
public long getRecordNumNear(long offset) throws IOException {
return getRecordNumByLocation(getLocationNear(offset));
}
/**
* Get a sample key that is within a block whose starting offset is greater
* than or equal to the specified offset.
@ -1058,7 +1083,7 @@ public Scanner createScanner() throws IOException {
* contains zero key-value pairs even if length is positive.
* @throws IOException
*/
public Scanner createScanner(long offset, long length) throws IOException {
public Scanner createScannerByByteRange(long offset, long length) throws IOException {
return new Scanner(this, offset, offset + length);
}
@ -1074,10 +1099,31 @@ public Scanner createScanner(long offset, long length) throws IOException {
* @return The actual coverage of the returned scanner will cover all keys
* greater than or equal to the beginKey and less than the endKey.
* @throws IOException
*
* @deprecated Use {@link #createScannerByKey(byte[], byte[])} instead.
*/
@Deprecated
public Scanner createScanner(byte[] beginKey, byte[] endKey)
throws IOException {
return createScannerByKey(beginKey, endKey);
}
/**
* Get a scanner that covers a portion of TFile based on keys.
*
* @param beginKey
* Begin key of the scan (inclusive). If null, scan from the first
* key-value entry of the TFile.
* @param endKey
* End key of the scan (exclusive). If null, scan up to the last
* key-value entry of the TFile.
* @return The actual coverage of the returned scanner will cover all keys
* greater than or equal to the beginKey and less than the endKey.
* @throws IOException
*/
public Scanner createScannerByKey(byte[] beginKey, byte[] endKey)
throws IOException {
return createScanner((beginKey == null) ? null : new ByteArray(beginKey,
return createScannerByKey((beginKey == null) ? null : new ByteArray(beginKey,
0, beginKey.length), (endKey == null) ? null : new ByteArray(endKey,
0, endKey.length));
}
@ -1094,9 +1140,31 @@ public Scanner createScanner(byte[] beginKey, byte[] endKey)
* @return The actual coverage of the returned scanner will cover all keys
* greater than or equal to the beginKey and less than the endKey.
* @throws IOException
*
* @deprecated Use {@link #createScannerByKey(RawComparable, RawComparable)}
* instead.
*/
@Deprecated
public Scanner createScanner(RawComparable beginKey, RawComparable endKey)
throws IOException {
return createScannerByKey(beginKey, endKey);
}
/**
* Get a scanner that covers a specific key range.
*
* @param beginKey
* Begin key of the scan (inclusive). If null, scan from the first
* key-value entry of the TFile.
* @param endKey
* End key of the scan (exclusive). If null, scan up to the last
* key-value entry of the TFile.
* @return The actual coverage of the returned scanner will cover all keys
* greater than or equal to the beginKey and less than the endKey.
* @throws IOException
*/
public Scanner createScannerByKey(RawComparable beginKey, RawComparable endKey)
throws IOException {
if ((beginKey != null) && (endKey != null)
&& (compareKeys(beginKey, endKey) >= 0)) {
return new Scanner(this, beginKey, beginKey);
@ -1104,6 +1172,27 @@ public Scanner createScanner(RawComparable beginKey, RawComparable endKey)
return new Scanner(this, beginKey, endKey);
}
/**
* Create a scanner that covers a range of records.
*
* @param beginRecNum
* The RecordNum for the first record (inclusive).
* @param endRecNum
* The RecordNum for the last record (exclusive). To scan the whole
* file, either specify endRecNum==-1 or endRecNum==getEntryCount().
* @return The TFile scanner that covers the specified range of records.
* @throws IOException
*/
public Scanner createScannerByRecordNum(long beginRecNum, long endRecNum)
throws IOException {
if (beginRecNum < 0) beginRecNum = 0;
if (endRecNum < 0 || endRecNum > getEntryCount()) {
endRecNum = getEntryCount();
}
return new Scanner(this, getLocationByRecordNum(beginRecNum),
getLocationByRecordNum(endRecNum));
}
/**
* The TFile Scanner. The Scanner has an implicit cursor, which, upon
* creation, points to the first key-value pair in the scan range. If the
@ -1523,6 +1612,15 @@ public Entry entry() throws IOException {
return new Entry();
}
/**
* Get the RecordNum corresponding to the entry pointed by the cursor.
* @return The RecordNum corresponding to the entry pointed by the cursor.
* @throws IOException
*/
public long getRecordNum() throws IOException {
return reader.getRecordNumByLocation(currentLocation);
}
/**
* Internal API. Comparing the key at cursor to user-specified key.
*
@ -2021,8 +2119,10 @@ static class TFileIndex {
final static String BLOCK_NAME = "TFile.index";
private ByteArray firstKey;
private final ArrayList<TFileIndexEntry> index;
private final ArrayList<Long> recordNumIndex;
private final BytesComparator comparator;
private long sum = 0;
/**
* For reading from file.
*
@ -2031,6 +2131,7 @@ static class TFileIndex {
public TFileIndex(int entryCount, DataInput in, BytesComparator comparator)
throws IOException {
index = new ArrayList<TFileIndexEntry>(entryCount);
recordNumIndex = new ArrayList<Long>(entryCount);
int size = Utils.readVInt(in); // size for the first key entry.
if (size > 0) {
byte[] buffer = new byte[size];
@ -2052,6 +2153,8 @@ public TFileIndex(int entryCount, DataInput in, BytesComparator comparator)
new TFileIndexEntry(new DataInputStream(new ByteArrayInputStream(
buffer, 0, size)));
index.add(idx);
sum += idx.entries();
recordNumIndex.add(sum);
}
} else {
if (entryCount != 0) {
@ -2083,6 +2186,12 @@ public int lowerBound(RawComparable key) {
return ret;
}
/**
* @param key
* input key.
* @return the ID of the first block that contains key > input key. Or -1
* if no such block exists.
*/
public int upperBound(RawComparable key) {
if (comparator == null) {
throw new RuntimeException("Cannot search in unsorted TFile");
@ -2104,13 +2213,26 @@ public int upperBound(RawComparable key) {
*/
public TFileIndex(BytesComparator comparator) {
index = new ArrayList<TFileIndexEntry>();
recordNumIndex = new ArrayList<Long>();
this.comparator = comparator;
}
public RawComparable getFirstKey() {
return firstKey;
}
public Reader.Location getLocationByRecordNum(long recNum) {
int idx = Utils.upperBound(recordNumIndex, recNum);
long lastRecNum = (idx == 0)? 0: recordNumIndex.get(idx-1);
return new Reader.Location(idx, recNum-lastRecNum);
}
public long getRecordNumByLocation(Reader.Location location) {
int blkIndex = location.getBlockIndex();
long lastRecNum = (blkIndex == 0) ? 0: recordNumIndex.get(blkIndex-1);
return lastRecNum + location.getRecordIndex();
}
public void setFirstKey(byte[] key, int offset, int length) {
firstKey = new ByteArray(new byte[length]);
System.arraycopy(key, offset, firstKey.buffer(), 0, length);
@ -2125,6 +2247,8 @@ public RawComparable getLastKey() {
public void addEntry(TFileIndexEntry keyEntry) {
index.add(keyEntry);
sum += keyEntry.entries();
recordNumIndex.add(sum);
}
public TFileIndexEntry getEntry(int bid) {

2
src/test/core/org/apache/hadoop/io/file/tfile/TestTFile.java
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@ -319,7 +319,7 @@ void basicWithSomeCodec(String codec) throws IOException {
scanner.close();
// test for a range of scanner
scanner = reader.createScanner(getSomeKey(10), getSomeKey(60));
scanner = reader.createScannerByKey(getSomeKey(10), getSomeKey(60));
readAndCheckbytes(scanner, 10, 50);
assertFalse(scanner.advance());
scanner.close();

8
src/test/core/org/apache/hadoop/io/file/tfile/TestTFileByteArrays.java
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@ -673,7 +673,7 @@ private void readValueBeforeKey(int count, int recordIndex)
Reader reader =
new Reader(fs.open(path), fs.getFileStatus(path).getLen(), conf);
Scanner scanner =
reader.createScanner(composeSortedKey(KEY, count, recordIndex)
reader.createScannerByKey(composeSortedKey(KEY, count, recordIndex)
.getBytes(), null);
try {
@ -698,7 +698,7 @@ private void readKeyWithoutValue(int count, int recordIndex)
throws IOException {
Reader reader = new Reader(fs.open(path), fs.getFileStatus(path).getLen(), conf);
Scanner scanner =
reader.createScanner(composeSortedKey(KEY, count, recordIndex)
reader.createScannerByKey(composeSortedKey(KEY, count, recordIndex)
.getBytes(), null);
try {
@ -729,7 +729,7 @@ private void readValueWithoutKey(int count, int recordIndex)
Reader reader = new Reader(fs.open(path), fs.getFileStatus(path).getLen(), conf);
Scanner scanner =
reader.createScanner(composeSortedKey(KEY, count, recordIndex)
reader.createScannerByKey(composeSortedKey(KEY, count, recordIndex)
.getBytes(), null);
byte[] vbuf1 = new byte[BUF_SIZE];
@ -753,7 +753,7 @@ private void readKeyManyTimes(int count, int recordIndex) throws IOException {
Reader reader = new Reader(fs.open(path), fs.getFileStatus(path).getLen(), conf);
Scanner scanner =
reader.createScanner(composeSortedKey(KEY, count, recordIndex)
reader.createScannerByKey(composeSortedKey(KEY, count, recordIndex)
.getBytes(), null);
// read the indexed key

87
src/test/core/org/apache/hadoop/io/file/tfile/TestTFileSplit.java
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@ -17,6 +17,7 @@
package org.apache.hadoop.io.file.tfile;
import java.io.IOException;
import java.util.Random;
import junit.framework.Assert;
import junit.framework.TestCase;
@ -42,6 +43,7 @@ public class TestTFileSplit extends TestCase {
private FileSystem fs;
private Configuration conf;
private Path path;
private Random random = new Random();
private String comparator = "memcmp";
private String outputFile = "TestTFileSplit";
@ -74,7 +76,7 @@ void readFile() throws IOException {
long rowCount = 0;
BytesWritable key, value;
for (int i = 0; i < numSplit; ++i, offset += splitSize) {
Scanner scanner = reader.createScanner(offset, splitSize);
Scanner scanner = reader.createScannerByByteRange(offset, splitSize);
int count = 0;
key = new BytesWritable();
value = new BytesWritable();
@ -90,18 +92,101 @@ void readFile() throws IOException {
Assert.assertEquals(rowCount, reader.getEntryCount());
reader.close();
}
/* Similar to readFile(), tests the scanner created
* by record numbers rather than the offsets.
*/
void readRowSplits(int numSplits) throws IOException {
Reader reader =
new Reader(fs.open(path), fs.getFileStatus(path).getLen(), conf);
long totalRecords = reader.getEntryCount();
for (int i=0; i<numSplits; i++) {
long startRec = i*totalRecords/numSplits;
long endRec = (i+1)*totalRecords/numSplits;
if (i == numSplits-1) {
endRec = totalRecords;
}
Scanner scanner = reader.createScannerByRecordNum(startRec, endRec);
int count = 0;
BytesWritable key = new BytesWritable();
BytesWritable value = new BytesWritable();
long x=startRec;
while (!scanner.atEnd()) {
assertEquals("Incorrect RecNum returned by scanner", scanner.getRecordNum(), x);
scanner.entry().get(key, value);
++count;
assertEquals("Incorrect RecNum returned by scanner", scanner.getRecordNum(), x);
scanner.advance();
++x;
}
scanner.close();
Assert.assertTrue(count == (endRec - startRec));
}
// make sure specifying range at the end gives zero records.
Scanner scanner = reader.createScannerByRecordNum(totalRecords, -1);
Assert.assertTrue(scanner.atEnd());
}
static String composeSortedKey(String prefix, int total, int value) {
return String.format("%s%010d", prefix, value);
}
void checkRecNums() throws IOException {
long fileLen = fs.getFileStatus(path).getLen();
Reader reader = new Reader(fs.open(path), fileLen, conf);
long totalRecs = reader.getEntryCount();
long begin = random.nextLong() % (totalRecs / 2);
if (begin < 0)
begin += (totalRecs / 2);
long end = random.nextLong() % (totalRecs / 2);
if (end < 0)
end += (totalRecs / 2);
end += (totalRecs / 2) + 1;
assertEquals("RecNum for offset=0 should be 0", 0, reader
.getRecordNumNear(0));
for (long x : new long[] { fileLen, fileLen + 1, 2 * fileLen }) {
assertEquals("RecNum for offset>=fileLen should be total entries",
totalRecs, reader.getRecordNumNear(x));
}
for (long i = 0; i < 100; ++i) {
assertEquals("Locaton to RecNum conversion not symmetric", i, reader
.getRecordNumByLocation(reader.getLocationByRecordNum(i)));
}
for (long i = 1; i < 100; ++i) {
long x = totalRecs - i;
assertEquals("Locaton to RecNum conversion not symmetric", x, reader
.getRecordNumByLocation(reader.getLocationByRecordNum(x)));
}
for (long i = begin; i < end; ++i) {
assertEquals("Locaton to RecNum conversion not symmetric", i, reader
.getRecordNumByLocation(reader.getLocationByRecordNum(i)));
}
for (int i = 0; i < 1000; ++i) {
long x = random.nextLong() % totalRecs;
if (x < 0) x += totalRecs;
assertEquals("Locaton to RecNum conversion not symmetric", x, reader
.getRecordNumByLocation(reader.getLocationByRecordNum(x)));
}
}
public void testSplit() throws IOException {
System.out.println("testSplit");
createFile(100000, Compression.Algorithm.NONE.getName());
checkRecNums();
readFile();
readRowSplits(10);
fs.delete(path, true);
createFile(500000, Compression.Algorithm.GZ.getName());
checkRecNums();
readFile();
readRowSplits(83);
fs.delete(path, true);
}
}

2
src/test/core/org/apache/hadoop/io/file/tfile/TestTFileUnsortedByteArrays.java
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@ -89,7 +89,7 @@ public void testFailureScannerWithKeys() throws IOException {
try {
Scanner scanner =
reader.createScanner("aaa".getBytes(), "zzz".getBytes());
reader.createScannerByKey("aaa".getBytes(), "zzz".getBytes());
Assert
.fail("Failed to catch creating scanner with keys on unsorted file.");
}