org.apache.flink.table.runtime.operators.window.slicing

接口 SliceSharedAssigner

所有超级接口:

Serializable, SliceAssigner

所有已知实现类:

SliceAssigners.CumulativeSliceAssigner, SliceAssigners.HoppingSliceAssigner, SliceAssigners.SlicedSharedSliceAssigner

@Internal
public interface SliceSharedAssigner
extends SliceAssigner

A SliceAssigner which shares slices for windows, which means a window is divided into multiple slices and need to merge the slices into windows when emitting windows.

Classical window of SliceSharedAssigner is hopping window.

嵌套类概要

嵌套类

限定符和类型	接口和说明
static interface	SliceSharedAssigner.MergeCallback Callback to be used in mergeSlices(long, MergeCallback) for specifying which slices should be merged.

方法概要

限定符和类型	方法和说明
void	mergeSlices(long sliceEnd, SliceSharedAssigner.MergeCallback callback) Determines which slices (if any) should be merged.
Optional<Long>	nextTriggerWindow(long windowEnd, java.util.function.Supplier<Boolean> isWindowEmpty) Returns the optional end timestamp of next window which should be triggered.

从接口继承的方法 org.apache.flink.table.runtime.operators.window.slicing.SliceAssigner

assignSliceEnd, expiredSlices, getLastWindowEnd, getSliceEndInterval, getWindowStart, isEventTime

方法详细资料

mergeSlices

void mergeSlices(long sliceEnd,
                 SliceSharedAssigner.MergeCallback callback)
          throws Exception

Determines which slices (if any) should be merged.

参数:

sliceEnd - the triggered slice, identified by end timestamp

callback - a callback that can be invoked to signal which slices should be merged.

抛出:

Exception

nextTriggerWindow

Optional<Long> nextTriggerWindow(long windowEnd,
                                 java.util.function.Supplier<Boolean> isWindowEmpty)

Returns the optional end timestamp of next window which should be triggered. Empty if no following window to trigger for now.

The purpose of this method is avoid register too many timers for each hopping and cumulative slice, e.g. HOP(1day, 10s) needs register 8640 timers for every slice. In order to improve this, we only register one timer for the next window. For hopping windows we don't register next window if current window is empty (i.e. no records in current window). That means we will have one more unnecessary window triggered for hopping windows if no elements arrives for a key for a long time. We will skip to emit window result for the triggered empty window, see SliceSharedWindowAggProcessor.fireWindow(Long).

参数:

windowEnd - the current triggered window, identified by end timestamp

isWindowEmpty - a supplier that can be invoked to get whether the triggered window is empty (i.e. no records in the window).