Package org.apache.storm.windowing

Class CountEvictionPolicy<T>

java.lang.Object

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

Type Parameters:

T - the type of event tracked by this policy.

All Implemented Interfaces:

EvictionPolicy<T,Long>

public class CountEvictionPolicy<T>
extends Object
implements EvictionPolicy<T,Long>

An eviction policy that tracks event counts and can evict based on a threshold count.

Nested Class Summary

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

EvictionPolicy.Action

Field Summary

Fields

Modifier and Type	Field	Description
protected AtomicLong	currentCount
protected int	threshold

Constructor Summary

Constructors

Constructor	Description
CountEvictionPolicy(int count)

Method Summary

Modifier and Type	Method	Description
EvictionPolicy.Action	evict(Event<T> event)	Decides if an event should be expired from the window, processed in the current window or kept for later processing.
EvictionContext	getContext()	Returns the current context that is part of this eviction policy.
Long	getState()	Return runtime state to be checkpointed by the framework for restoring the eviction policy in case of failures.
void	reset()	Resets the eviction policy.
void	restoreState(Long state)	Restore the eviction policy from the state that was earlier checkpointed by the framework.
void	setContext(EvictionContext context)	Sets a context in the eviction policy that can be used while evicting the events.
String	toString()
void	track(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

threshold

protected final int threshold

currentCount

protected final AtomicLong currentCount

Constructor Detail

CountEvictionPolicy

public CountEvictionPolicy(int count)

Method Detail

evict

public EvictionPolicy.Action evict(Event<T> event)

Description copied from interface: EvictionPolicy

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,Long>

Parameters:

event - the input event

Returns:

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

track

public void track(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,Long>

Parameters:

event - the input event to be tracked

getContext

public EvictionContext getContext()

Description copied from interface: EvictionPolicy

Returns the current context that is part of this eviction policy.

Specified by:

getContext in interface EvictionPolicy<T,Long>

Returns:

the eviction context

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,Long>

Parameters:

context - the eviction context

toString

public String toString()

Overrides:

toString in class Object

reset

public void reset()

Description copied from interface: EvictionPolicy

Resets the eviction policy.

Specified by:

reset in interface EvictionPolicy<T,Long>

getState

public Long getState()

Description copied from interface: EvictionPolicy

Return runtime state to be checkpointed by the framework for restoring the eviction policy in case of failures.

Specified by:

getState in interface EvictionPolicy<T,Long>

Returns:

the state

restoreState

public void restoreState(Long state)

Description copied from interface: EvictionPolicy

Restore the eviction policy from the state that was earlier checkpointed by the framework.

Specified by:

restoreState in interface EvictionPolicy<T,Long>

Parameters:

state - the state