org.apache.druid.frame.write

Class RowBasedFrameWriter

java.lang.Object

org.apache.druid.frame.write.RowBasedFrameWriter

All Implemented Interfaces:

Closeable, AutoCloseable, FrameWriter

public class RowBasedFrameWriter
extends Object
implements FrameWriter

Write row-based frames: type FrameType.ROW_BASED. Row-based frames have two regions: an offset region and data region. The offset region has one integer per row containing the ending position of each row within the data region. The data region has each row laid out back to back. Each row has a header section with one int per field, containing the end position of that field relative to the start of the row. This header is followed by the fields.

Field Summary

Fields

Modifier and Type	Field and Description
static int	NUM_REGIONS
static int	ROW_DATA_REGION
static int	ROW_OFFSET_REGION

Constructor Summary

Constructors

Constructor and Description
RowBasedFrameWriter(RowSignature signature, List<KeyColumn> sortColumns, List<FieldWriter> fieldWriters, Supplier<MemoryRange<org.apache.datasketches.memory.Memory>> rowMemorySupplier, AppendableMemory rowOrderMemory, AppendableMemory rowOffsetMemory, AppendableMemory dataMemory)

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 FrameWriter.writeTo(org.apache.datasketches.memory.WritableMemory, long) if called now.
long	writeTo(org.apache.datasketches.memory.WritableMemory memory, long startPosition) Writes the frame to the provided memory location, which must have at least FrameWriter.getTotalSize() bytes available.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.frame.write.FrameWriter

toByteArray

Field Detail

ROW_OFFSET_REGION

public static final int ROW_OFFSET_REGION

See Also:

Constant Field Values

ROW_DATA_REGION

public static final int ROW_DATA_REGION

See Also:

Constant Field Values

NUM_REGIONS

public static final int NUM_REGIONS

See Also:

Constant Field Values

Constructor Detail

RowBasedFrameWriter

public RowBasedFrameWriter(RowSignature signature,
                           List<KeyColumn> sortColumns,
                           List<FieldWriter> fieldWriters,
                           @Nullable
                           Supplier<MemoryRange<org.apache.datasketches.memory.Memory>> rowMemorySupplier,
                           @Nullable
                           AppendableMemory rowOrderMemory,
                           AppendableMemory rowOffsetMemory,
                           AppendableMemory dataMemory)

Method Detail

addSelection

public boolean addSelection()

Description copied from interface: FrameWriter

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.

Specified by:

addSelection in interface FrameWriter

Returns:

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

getNumRows

public int getNumRows()

Description copied from interface: FrameWriter

Returns the number of rows written so far.

Specified by:

getNumRows in interface FrameWriter

getTotalSize

public long getTotalSize()

Description copied from interface: FrameWriter

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

Specified by:

getTotalSize in interface FrameWriter

writeTo

public long writeTo(org.apache.datasketches.memory.WritableMemory memory,
                    long startPosition)

Description copied from interface: FrameWriter

Writes the frame to the provided memory location, which must have at least FrameWriter.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 FrameWriter.getTotalSize().

Specified by:

writeTo in interface FrameWriter

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface FrameWriter