org.apache.flink.table.runtime.operators.aggregate.window.buffers

Interface WindowBuffer

All Known Implementing Classes:

RecordsWindowBuffer

@Internal
public interface WindowBuffer

A buffer that buffers data in memory and flushes many values to state together at a time to avoid frequently accessing state, or flushes to output to reduce shuffling data.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	WindowBuffer.Factory A factory that creates a WindowBuffer.
static interface	WindowBuffer.LocalFactory A factory that creates a WindowBuffer.

Method Summary

Modifier and Type	Method and Description
void	addElement(RowData key, long window, RowData element) Adds an element with associated key into the buffer.
void	advanceProgress(long progress) Advances the progress time, the progress time is watermark if working in event-time mode, or current processing time if working in processing-time mode.
void	close() Release resources allocated by this buffer.
void	flush() Flushes all intermediate buffered data to the underlying backend or output stream.

Method Detail

addElement

void addElement(RowData key,
                long window,
                RowData element)
         throws Exception

Adds an element with associated key into the buffer. The buffer may temporarily buffer the element, or immediately write it to the stream.

It may be that adding this element fills up an internal buffer and causes the buffer flushing of a batch of internally buffered elements.

Parameters:

key - the key associated with the element

element - The element to add.

Throws:

Exception - Thrown, if the element cannot be added to the buffer, or if the flushing throws an exception.

advanceProgress

void advanceProgress(long progress)
              throws Exception

Advances the progress time, the progress time is watermark if working in event-time mode, or current processing time if working in processing-time mode.

This will potentially flush buffered data into states or to the output stream, because the watermark advancement may be in a very small step, but we don't need to flush buffered data for every watermark advancement.

Parameters:

progress - the current progress time

Throws:

Exception

flush

void flush()
    throws Exception

Flushes all intermediate buffered data to the underlying backend or output stream.

Throws:

Exception - Thrown if the buffer cannot be flushed, or if the output stream throws an exception.

close

void close()
    throws Exception

Release resources allocated by this buffer.

Throws:

Exception