org.apache.flink.runtime.memory

Class AbstractPagedOutputView

java.lang.Object

org.apache.flink.runtime.memory.AbstractPagedOutputView

All Implemented Interfaces:

DataOutput, DataOutputView

Direct Known Subclasses:

ChannelWriterOutputView, FileChannelOutputView, HashPartition.BuildSideBuffer, RandomAccessOutputView, SerializedUpdateBuffer, SimpleCollectingOutputView, SpillingBuffer

public abstract class AbstractPagedOutputView
extends Object
implements DataOutputView

The base class for all output views that are backed by multiple memory pages. This base class contains all encoding methods to write data to a page and detect page boundary crossing. The concrete sub classes must implement the methods to collect the current page and provide the next memory page once the boundary is crossed.

The paging assumes that all memory segments are of the same size.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	headerLength
protected int	segmentSize

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractPagedOutputView(int segmentSize, int headerLength)
protected	AbstractPagedOutputView(MemorySegment initialSegment, int segmentSize, int headerLength) Creates a new output view that writes initially to the given initial segment.

Method Summary

Modifier and Type	Method and Description
protected void	advance() Moves the output view to the next page.
protected void	clear() Clears the internal state.
int	getCurrentPositionInSegment() Gets the current write position (the position where the next bytes will be written) in the current memory segment.
MemorySegment	getCurrentSegment() Gets the segment that the view currently writes to.
int	getSegmentSize() Gets the size of the segments used by this view.
protected abstract MemorySegment	nextSegment(MemorySegment current, int positionInCurrent) This method must return a segment.
protected void	seekOutput(MemorySegment seg, int position) Sets the internal state to the given memory segment and the given position within the segment.
void	skipBytesToWrite(int numBytes) Skips numBytes bytes memory.
void	write(byte[] b)
void	write(byte[] b, int off, int len)
void	write(DataInputView source, int numBytes) Copies numBytes bytes from the source to this view.
void	write(int b)
void	writeBoolean(boolean v)
void	writeByte(int v)
void	writeBytes(String s)
void	writeChar(int v)
void	writeChars(String s)
void	writeDouble(double v)
void	writeFloat(float v)
void	writeInt(int v)
void	writeLong(long v)
void	writeShort(int v)
void	writeUTF(String str)

Methods inherited from class java.lang.Object

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

Field Detail

segmentSize

protected final int segmentSize

headerLength

protected final int headerLength

Constructor Detail

AbstractPagedOutputView

protected AbstractPagedOutputView(MemorySegment initialSegment,
                                  int segmentSize,
                                  int headerLength)

Creates a new output view that writes initially to the given initial segment. All segments in the view have to be of the given segmentSize. A header of length headerLength is left at the beginning of each segment.

Parameters:

initialSegment - The segment that the view starts writing to.

segmentSize - The size of the memory segments.

headerLength - The number of bytes to skip at the beginning of each segment for the header.

AbstractPagedOutputView

protected AbstractPagedOutputView(int segmentSize,
                                  int headerLength)

Parameters:

segmentSize - The size of the memory segments.

headerLength - The number of bytes to skip at the beginning of each segment for the header.

Method Detail

nextSegment

protected abstract MemorySegment nextSegment(MemorySegment current,
                                             int positionInCurrent)
                                      throws IOException

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

Parameters:

current - The current memory segment

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

Returns:

The next memory segment.

Throws:

IOException

getCurrentSegment

public MemorySegment getCurrentSegment()

Gets the segment that the view currently writes to.

Returns:

The segment the view currently writes to.

getCurrentPositionInSegment

public int getCurrentPositionInSegment()

Gets the current write position (the position where the next bytes will be written) in the current memory segment.

Returns:

The current write offset in the current memory segment.

getSegmentSize

public int getSegmentSize()

Gets the size of the segments used by this view.

Returns:

The memory segment size.

advance

protected void advance()
                throws IOException

Moves the output view to the next page. This method invokes internally the nextSegment(MemorySegment, int) method to give the current memory segment to the concrete subclass' implementation and obtain the next segment to write to. Writing will continue inside the new segment after the header.

Throws:

IOException - Thrown, if the current segment could not be processed or a new segment could not be obtained.

seekOutput

protected void seekOutput(MemorySegment seg,
                          int position)

Sets the internal state to the given memory segment and the given position within the segment.

Parameters:

seg - The memory segment to write the next bytes to.

position - The position to start writing the next bytes to.

clear

protected void clear()

Clears the internal state. Any successive write calls will fail until either advance() or seekOutput(MemorySegment, int) is called.

See Also:

advance(), seekOutput(MemorySegment, int)

write

public void write(int b)
           throws IOException

Specified by:

write in interface DataOutput

Throws:

IOException

write

public void write(byte[] b)
           throws IOException

Specified by:

write in interface DataOutput

Throws:

IOException

write

public void write(byte[] b,
                  int off,
                  int len)
           throws IOException

Specified by:

write in interface DataOutput

Throws:

IOException

writeBoolean

public void writeBoolean(boolean v)
                  throws IOException

Specified by:

writeBoolean in interface DataOutput

Throws:

IOException

writeByte

public void writeByte(int v)
               throws IOException

Specified by:

writeByte in interface DataOutput

Throws:

IOException

writeShort

public void writeShort(int v)
                throws IOException

Specified by:

writeShort in interface DataOutput

Throws:

IOException

writeChar

public void writeChar(int v)
               throws IOException

Specified by:

writeChar in interface DataOutput

Throws:

IOException

writeInt

public void writeInt(int v)
              throws IOException

Specified by:

writeInt in interface DataOutput

Throws:

IOException

writeLong

public void writeLong(long v)
               throws IOException

Specified by:

writeLong in interface DataOutput

Throws:

IOException

writeFloat

public void writeFloat(float v)
                throws IOException

Specified by:

writeFloat in interface DataOutput

Throws:

IOException

writeDouble

public void writeDouble(double v)
                 throws IOException

Specified by:

writeDouble in interface DataOutput

Throws:

IOException

writeBytes

public void writeBytes(String s)
                throws IOException

Specified by:

writeBytes in interface DataOutput

Throws:

IOException

writeChars

public void writeChars(String s)
                throws IOException

Specified by:

writeChars in interface DataOutput

Throws:

IOException

writeUTF

public void writeUTF(String str)
              throws IOException

Specified by:

writeUTF in interface DataOutput

Throws:

IOException

skipBytesToWrite

public void skipBytesToWrite(int numBytes)
                      throws IOException

Description copied from interface: DataOutputView

Skips numBytes bytes memory. If some program reads the memory that was skipped over, the results are undefined.

Specified by:

skipBytesToWrite in interface DataOutputView

Parameters:

numBytes - The number of bytes to skip.

Throws:

IOException - Thrown, if any I/O related problem occurred such that the view could not be advanced to the desired position.

write

public void write(DataInputView source,
                  int numBytes)
           throws IOException

Description copied from interface: DataOutputView

Copies numBytes bytes from the source to this view.

Specified by:

write in interface DataOutputView

Parameters:

source - The source to copy the bytes from.

numBytes - The number of bytes to copy.

Throws:

IOException - Thrown, if any I/O related problem occurred, such that either the input view could not be read, or the output could not be written.