org.apache.flink.streaming.api.windowing.policy

Interface ActiveEvictionPolicy<DATA>

All Superinterfaces:

EvictionPolicy<DATA>, Serializable

All Known Implementing Classes:

ActiveCloneableEvictionPolicyWrapper, ActiveEvictionPolicyWrapper, CloneableMultiEvictionPolicy, MultiEvictionPolicy, TimeEvictionPolicy

public interface ActiveEvictionPolicy<DATA>
extends EvictionPolicy<DATA>

This interface is used for active eviction policies. beside the functionality inherited from EvictionPolicy it provides a method which gets called to notify on fake elements. In case an eviction policy implements this interface instead of the EvictionPolicy interface, not only the real but also fake data points will cause a notification of the eviction. Fake data points are mostly used in windowing based on time to trigger and evict even if no element arrives at all during a windows duration.

Method Summary

Modifier and Type	Method and Description
int	notifyEvictionWithFakeElement(Object datapoint, int bufferSize) Proves if and how many elements should be deleted from the element buffer.

Methods inherited from interface org.apache.flink.streaming.api.windowing.policy.EvictionPolicy

notifyEviction

Method Detail

notifyEvictionWithFakeElement

int notifyEvictionWithFakeElement(Object datapoint,
                                  int bufferSize)

Proves if and how many elements should be deleted from the element buffer. The eviction takes place after the trigger and after the call to the UDF. This method is only called with fake elements. Note: Fake elements are always considered as triggered. Therefore this method does not have a triggered parameter.

Parameters:

datapoint - the current fake data point

bufferSize - the current size of the buffer (only real elements are counted)

Returns:

the number of elements to delete from the buffer (only real elements are counted)