Package org.apache.storm.windowing
Interface EvictionPolicy<T,S> 
- Type Parameters:
- T- the type of event that is tracked.
- All Known Implementing Classes:
- CountEvictionPolicy,- TimeEvictionPolicy,- WatermarkCountEvictionPolicy,- WatermarkTimeEvictionPolicy
public interface EvictionPolicy<T,S> 
Eviction policy tracks events and decides whether an event should be evicted from the window or not.
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Nested Class SummaryNested ClassesModifier and TypeInterfaceDescriptionstatic enumThe action to be taken whenevict(Event)is invoked.
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Method SummaryModifier and TypeMethodDescriptionDecides if an event should be expired from the window, processed in the current window or kept for later processing.Returns the current context that is part of this eviction policy.getState()Return runtime state to be checkpointed by the framework for restoring the eviction policy in case of failures.voidreset()Resets the eviction policy.voidrestoreState(S state) Restore the eviction policy from the state that was earlier checkpointed by the framework.voidsetContext(EvictionContext context) Sets a context in the eviction policy that can be used while evicting the events.voidTracks the event to later decide whetherevict(Event)should evict it or not.
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Method Details- 
evictDecides if an event should be expired from the window, processed in the current window or kept for later processing.- Parameters:
- event- the input event
- Returns:
- the EvictionPolicy.Actionto be taken based on the input event
 
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trackTracks the event to later decide whetherevict(Event)should evict it or not.- Parameters:
- event- the input event to be tracked
 
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getContextEvictionContext getContext()Returns the current context that is part of this eviction policy.- Returns:
- the eviction context
 
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setContextSets 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.- Parameters:
- context- the eviction context
 
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resetvoid reset()Resets the eviction policy.
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getStateS getState()Return runtime state to be checkpointed by the framework for restoring the eviction policy in case of failures.- Returns:
- the state
 
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restoreStateRestore the eviction policy from the state that was earlier checkpointed by the framework.- Parameters:
- state- the state
 
 
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