org.apache.druid.frame.write

Interface FrameWriter

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

ColumnarFrameWriter, RowBasedFrameWriter

public interface FrameWriter
extends Closeable

Writer for Frame. See that class for format information. Generally obtained through a FrameWriters.makeFrameWriterFactory(org.apache.druid.frame.FrameType, org.apache.druid.frame.allocation.MemoryAllocatorFactory, org.apache.druid.segment.column.RowSignature, java.util.List<org.apache.druid.frame.key.KeyColumn>).

Method Summary

Modifier and Type	Method and Description
boolean	addSelection() Write the current row to the frame that is under construction, if there is enough space to do so.
void	close()
int	getNumRows() Returns the number of rows written so far.
long	getTotalSize() Returns the number of bytes that would be written by writeTo(org.apache.datasketches.memory.WritableMemory, long) if called now.
default byte[]	toByteArray() Returns a frame as a newly-allocated byte array.
long	writeTo(org.apache.datasketches.memory.WritableMemory memory, long position) Writes the frame to the provided memory location, which must have at least getTotalSize() bytes available.

Method Detail

addSelection

boolean addSelection()

Write the current row to the frame that is under construction, if there is enough space to do so.

If this method returns false on an empty frame, or in a situation where starting a new frame is impractical, it is conventional (although not required) for the caller to throw FrameRowTooLargeException.

Returns:

true if the row was written, false if there was not enough space

getNumRows

int getNumRows()

Returns the number of rows written so far.

getTotalSize

long getTotalSize()

Returns the number of bytes that would be written by writeTo(org.apache.datasketches.memory.WritableMemory, long) if called now.

writeTo

long writeTo(org.apache.datasketches.memory.WritableMemory memory,
             long position)

Writes the frame to the provided memory location, which must have at least getTotalSize() bytes available. Once this method is called, the frame writer is no longer usable and must be closed. Returns the number of bytes written, which will equal getTotalSize().

Throws:

IllegalStateException - if the provided memory does not have sufficient space to write this frame.

toByteArray

default byte[] toByteArray()

Returns a frame as a newly-allocated byte array. Once this method is called, the frame writer is no longer usable and must be closed. In general, it is more efficient to write a frame into a pre-existing buffer, but this method is provided as a convenience.

close

void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable