org.apache.hadoop.mapred

Class MapTask.MapOutputBuffer.BlockingBuffer

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

java.io.DataOutputStream

org.apache.hadoop.mapred.MapTask.MapOutputBuffer.BlockingBuffer

All Implemented Interfaces:

Closeable, DataOutput, Flushable, AutoCloseable

Enclosing class:

MapTask.MapOutputBuffer<K,V>

protected class MapTask.MapOutputBuffer.BlockingBuffer
extends DataOutputStream

Inner class managing the spill of serialized records to disk.

Field Summary

Fields inherited from class java.io.DataOutputStream

written

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
BlockingBuffer()

Method Summary

Modifier and Type	Method and Description
int	markRecord() Mark end of record.
protected void	shiftBufferedKey() Set position from last mark to end of writable buffer, then rewrite the data between last mark and kvindex.

Methods inherited from class java.io.DataOutputStream

flush, size, write, write, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeDouble, writeFloat, writeInt, writeLong, writeShort, writeUTF

Methods inherited from class java.io.FilterOutputStream

close, write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.io.DataOutput

write

Constructor Detail

BlockingBuffer

public BlockingBuffer()

Method Detail

markRecord

public int markRecord()

Mark end of record. Note that this is required if the buffer is to cut the spill in the proper place.

shiftBufferedKey

protected void shiftBufferedKey()
                         throws IOException

Set position from last mark to end of writable buffer, then rewrite the data between last mark and kvindex. This handles a special case where the key wraps around the buffer. If the key is to be passed to a RawComparator, then it must be contiguous in the buffer. This recopies the data in the buffer back into itself, but starting at the beginning of the buffer. Note that this method should only be called immediately after detecting this condition. To call it at any other time is undefined and would likely result in data loss or corruption.

Throws:

IOException

See Also:

markRecord()