org.apache.spark.storage

Class BlockObjectWriter

Object

org.apache.spark.storage.BlockObjectWriter

Direct Known Subclasses:

DiskBlockObjectWriter

public abstract class BlockObjectWriter
extends Object

An interface for writing JVM objects to some underlying storage. This interface allows appending data to an existing block, and can guarantee atomicity in the case of faults as it allows the caller to revert partial writes.

This interface does not support concurrent writes. Also, once the writer has been opened, it cannot be reopened again.

Constructor Summary

Constructors

Constructor and Description
BlockObjectWriter(BlockId blockId)

Method Summary

Methods

Modifier and Type	Method and Description
BlockId	blockId()
abstract void	close()
abstract void	commitAndClose() Flush the partial writes and commit them as a single atomic block.
abstract FileSegment	fileSegment() Returns the file segment of committed data that this Writer has written.
abstract boolean	isOpen()
abstract BlockObjectWriter	open()
abstract void	revertPartialWritesAndClose() Reverts writes that haven't been flushed yet.
abstract void	write(Object value) Writes an object.

Methods inherited from class Object

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

Constructor Detail

BlockObjectWriter

public BlockObjectWriter(BlockId blockId)

Method Detail

blockId

public BlockId blockId()

open

public abstract BlockObjectWriter open()

close

public abstract void close()

isOpen

public abstract boolean isOpen()

commitAndClose

public abstract void commitAndClose()

Flush the partial writes and commit them as a single atomic block.

revertPartialWritesAndClose

public abstract void revertPartialWritesAndClose()

Reverts writes that haven't been flushed yet. Callers should invoke this function when there are runtime exceptions. This method will not throw, though it may be unsuccessful in truncating written data.

write

public abstract void write(Object value)

Writes an object.

fileSegment

public abstract FileSegment fileSegment()

Returns the file segment of committed data that this Writer has written. This is only valid after commitAndClose() has been called.