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

Class PunctuationPolicy<IN,DATA>

java.lang.Object

org.apache.flink.streaming.api.windowing.policy.PunctuationPolicy<IN,DATA>

Type Parameters:

IN - The type of the input data handled by this policy. An Extractor can be used to extract DATA for IN.

DATA - The type of the punctuation. An Extractor can be used to extract DATA for IN.

All Implemented Interfaces:

Serializable, Cloneable, CloneableEvictionPolicy<IN>, CloneableTriggerPolicy<IN>, EvictionPolicy<IN>, TriggerPolicy<IN>

public class PunctuationPolicy<IN,DATA>
extends Object
implements CloneableTriggerPolicy<IN>, CloneableEvictionPolicy<IN>

This policy can be used to trigger and evict based on a punctuation which is present within the arriving data. Using this policy, one can react on an externally defined arbitrary windowing semantic. In case this policy is used for eviction, the complete buffer will get deleted in case the punctuation is detected. By default this policy does not react on fake elements. Wrap it in an ActiveEvictionPolicyWrapper to make it react on punctuation even in fake elements.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
PunctuationPolicy(DATA punctuation) Creates the punctuation policy without using any extractor.
PunctuationPolicy(DATA punctuation, Extractor<IN,DATA> extractor) Creates the punctuation policy which uses the specified extractor to isolate the punctuation from the data.

Method Summary

Modifier and Type	Method and Description
PunctuationPolicy<IN,DATA>	clone() This method should return an exact copy of the object it belongs to including the current object state.
boolean	equals(Object other)
int	notifyEviction(IN datapoint, boolean triggered, int bufferSize) Proves if and how many elements should be deleted from the element buffer.
boolean	notifyTrigger(IN datapoint) Proves and returns if a new window should be started.
String	toString()

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PunctuationPolicy

public PunctuationPolicy(DATA punctuation)

Creates the punctuation policy without using any extractor. To make this work IN and DATA must not be different types.

Parameters:

punctuation - the punctuation which leads to trigger/evict.

PunctuationPolicy

public PunctuationPolicy(DATA punctuation,
                         Extractor<IN,DATA> extractor)

Creates the punctuation policy which uses the specified extractor to isolate the punctuation from the data.

Parameters:

punctuation - the punctuation which leads to trigger/evict.

extractor - An Extractor which converts IN to DATA.

Method Detail

notifyEviction

public int notifyEviction(IN datapoint,
                          boolean triggered,
                          int bufferSize)

Description copied from interface: EvictionPolicy

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 but before the adding of the new data point.

Specified by:

notifyEviction in interface EvictionPolicy<IN>

Parameters:

datapoint - data point the data point which arrived

triggered - Information whether the UDF was triggered or not

bufferSize - The current size of the element buffer at the operator

Returns:

The number of elements to be deleted from the buffer

notifyTrigger

public boolean notifyTrigger(IN datapoint)

Description copied from interface: TriggerPolicy

Proves and returns if a new window should be started. In case the trigger occurs (return value true) the UDF will be executed on the current element buffer without the last added element which is provided as parameter. This element will be added to the buffer after the execution of the UDF. There are possibly different strategies for eviction and triggering: 1) including last data point: Better/faster for count eviction 2) excluding last data point: Essentially required for time based eviction and delta rules As 2) is required for some policies and the benefit of using 1) is small for the others, policies are implemented according to 2).

Specified by:

notifyTrigger in interface TriggerPolicy<IN>

Parameters:

datapoint - the data point which arrived

Returns:

true if the current windows should be closed, otherwise false. In true case the given data point will be part of the next window and will not be included in the current one.

clone

public PunctuationPolicy<IN,DATA> clone()

Description copied from interface: CloneableTriggerPolicy

This method should return an exact copy of the object it belongs to including the current object state.

Specified by:

clone in interface CloneableEvictionPolicy<IN>

Specified by:

clone in interface CloneableTriggerPolicy<IN>

Overrides:

clone in class Object

Returns:

a copy of this object

equals

public boolean equals(Object other)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object