org.apache.storm.windowing

Class TimeEvictionPolicy<T>

java.lang.Object

org.apache.storm.windowing.TimeEvictionPolicy<T>

All Implemented Interfaces:

EvictionPolicy<T>

Direct Known Subclasses:

WatermarkTimeEvictionPolicy

public class TimeEvictionPolicy<T>
extends Object
implements EvictionPolicy<T>

Eviction policy that evicts events based on time duration.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.storm.windowing.EvictionPolicy

EvictionPolicy.Action

Field Summary

Fields

Modifier and Type	Field and Description
protected EvictionContext	evictionContext
protected Long	referenceTime The reference time in millis for window calculations and expiring events.

Constructor Summary

Constructors

Constructor and Description
TimeEvictionPolicy(int windowLength) Constructs a TimeEvictionPolicy that evicts events older than the given window length in millis

Method Summary

Modifier and Type	Method and Description
EvictionPolicy.Action	evict(org.apache.storm.windowing.Event<T> event) Decides if an event should be expired from the window, processed in the current window or kept for later processing.
void	setContext(EvictionContext context) Sets a context in the eviction policy that can be used while evicting the events.
String	toString()
void	track(org.apache.storm.windowing.Event<T> event) Tracks the event to later decide whether EvictionPolicy.evict(Event) should evict it or not.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

referenceTime

protected Long referenceTime

The reference time in millis for window calculations and expiring events. If not set it will default to System.currentTimeMillis()

evictionContext

protected EvictionContext evictionContext

Constructor Detail

TimeEvictionPolicy

public TimeEvictionPolicy(int windowLength)

Constructs a TimeEvictionPolicy that evicts events older than the given window length in millis

Parameters:

windowLength - the duration in milliseconds

Method Detail

evict

public EvictionPolicy.Action evict(org.apache.storm.windowing.Event<T> event)

Decides if an event should be expired from the window, processed in the current window or kept for later processing.

Specified by:

evict in interface EvictionPolicy<T>

Parameters:

event - the input event

Returns:

the EvictionPolicy.Action to be taken based on the input event

track

public void track(org.apache.storm.windowing.Event<T> event)

Description copied from interface: EvictionPolicy

Tracks the event to later decide whether EvictionPolicy.evict(Event) should evict it or not.

Specified by:

track in interface EvictionPolicy<T>

Parameters:

event - the input event to be tracked

setContext

public void setContext(EvictionContext context)

Description copied from interface: EvictionPolicy

Sets a context in the eviction policy that can be used while evicting the events. E.g. For TimeEvictionPolicy, this could be used to set the reference timestamp.

Specified by:

setContext in interface EvictionPolicy<T>

toString

public String toString()

Overrides:

toString in class Object