Package 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
    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
    Description
    void
    addElement(org.apache.flink.table.data.RowData key, long window, org.apache.flink.table.data.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 Details

    • addElement

      void addElement(org.apache.flink.table.data.RowData key, long window, org.apache.flink.table.data.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