org.apache.flink.runtime.io.disk.iomanager

Class ChannelWriterOutputView

java.lang.Object

org.apache.flink.runtime.memory.AbstractPagedOutputView

org.apache.flink.runtime.io.disk.iomanager.ChannelWriterOutputView

All Implemented Interfaces:

DataOutput, DataOutputView

public final class ChannelWriterOutputView
extends AbstractPagedOutputView

A DataOutputView that is backed by a BlockChannelWriter, making it effectively a data output stream. The view writes its data in blocks to the underlying channel, adding a minimal header to each block. The data can be re-read by a ChannelReaderInputView, if it uses the same block size.

Field Summary

Fields

Modifier and Type	Field and Description
protected static short	FLAG_LAST_BLOCK The flag marking a block as the last block.
protected static int	HEAD_BLOCK_LENGTH_OFFSET The offset to the header field indicating the number of bytes in the block
protected static int	HEADER_FLAGS_OFFSET The offset to the flags in the header;
protected static int	HEADER_LENGTH The length of the header put into the blocks.
protected static short	HEADER_MAGIC_NUMBER The magic number that identifies blocks as blocks from a ChannelWriterOutputView.

Fields inherited from class org.apache.flink.runtime.memory.AbstractPagedOutputView

headerLength, segmentSize

Constructor Summary

Constructors

Constructor and Description
ChannelWriterOutputView(BlockChannelWriter<MemorySegment> writer, int segmentSize) Creates an new ChannelWriterOutputView that writes to the given channel.
ChannelWriterOutputView(BlockChannelWriter<MemorySegment> writer, List<MemorySegment> memory, int segmentSize) Creates an new ChannelWriterOutputView that writes to the given channel and buffers data in the given memory segments.

Method Summary

Modifier and Type	Method and Description
List<MemorySegment>	close() Closes this OutputView, closing the underlying writer and returning all memory segments.
int	getBlockCount() Gets the number of blocks used by this view.
long	getBytesMemoryUsed() Gets the number of bytes used by this output view, including written bytes and header bytes.
long	getBytesWritten() Gets the number of pay-load bytes already written.
protected MemorySegment	nextSegment(MemorySegment current, int posInSegment) This method must return a segment.

Methods inherited from class org.apache.flink.runtime.memory.AbstractPagedOutputView

advance, clear, getCurrentPositionInSegment, getCurrentSegment, getSegmentSize, seekOutput, skipBytesToWrite, write, write, write, write, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeDouble, writeFloat, writeInt, writeLong, writeShort, writeUTF

Methods inherited from class java.lang.Object

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

Field Detail

HEADER_MAGIC_NUMBER

protected static final short HEADER_MAGIC_NUMBER

The magic number that identifies blocks as blocks from a ChannelWriterOutputView.

See Also:

Constant Field Values

HEADER_LENGTH

protected static final int HEADER_LENGTH

The length of the header put into the blocks.

See Also:

Constant Field Values

HEADER_FLAGS_OFFSET

protected static final int HEADER_FLAGS_OFFSET

The offset to the flags in the header;

See Also:

Constant Field Values

HEAD_BLOCK_LENGTH_OFFSET

protected static final int HEAD_BLOCK_LENGTH_OFFSET

The offset to the header field indicating the number of bytes in the block

See Also:

Constant Field Values

FLAG_LAST_BLOCK

protected static final short FLAG_LAST_BLOCK

The flag marking a block as the last block.

See Also:

Constant Field Values

Constructor Detail

ChannelWriterOutputView

public ChannelWriterOutputView(BlockChannelWriter<MemorySegment> writer,
                               List<MemorySegment> memory,
                               int segmentSize)

Creates an new ChannelWriterOutputView that writes to the given channel and buffers data in the given memory segments. If the given memory segments are null, the writer takes its buffers directly from the return queue of the writer. Note that this variant locks if no buffers are contained in the return queue.

Parameters:

writer - The writer to write to.

memory - The memory used to buffer data, or null, to utilize solely the return queue.

segmentSize - The size of the memory segments.

ChannelWriterOutputView

public ChannelWriterOutputView(BlockChannelWriter<MemorySegment> writer,
                               int segmentSize)

Creates an new ChannelWriterOutputView that writes to the given channel. It uses only a single memory segment for the buffering, which it takes from the writer's return queue. Note that this variant locks if no buffers are contained in the return queue.

Parameters:

writer - The writer to write to.

segmentSize - The size of the memory segments.

Method Detail

close

public List<MemorySegment> close()
                          throws IOException

Closes this OutputView, closing the underlying writer and returning all memory segments.

Returns:

A list containing all memory segments originally supplied to this view.

Throws:

IOException - Thrown, if the underlying writer could not be properly closed.

getBlockCount

public int getBlockCount()

Gets the number of blocks used by this view.

Returns:

The number of blocks used.

getBytesWritten

public long getBytesWritten()

Gets the number of pay-load bytes already written. This excludes the number of bytes spent on headers in the segments.

Returns:

The number of bytes that have been written to this output view.

getBytesMemoryUsed

public long getBytesMemoryUsed()

Gets the number of bytes used by this output view, including written bytes and header bytes.

Returns:

The number of bytes that have been written to this output view.

nextSegment

protected final MemorySegment nextSegment(MemorySegment current,
                                          int posInSegment)
                                   throws IOException

Description copied from class: AbstractPagedOutputView

This method must return a segment. If no more segments are available, it must throw an EOFException.

Specified by:

nextSegment in class AbstractPagedOutputView

Parameters:

current - The current memory segment

posInSegment - The position in the segment, one after the last valid byte.

Returns:

The next memory segment.

Throws:

IOException