org.apache.storm.policy

Class WaitStrategyProgressive

java.lang.Object

org.apache.storm.policy.WaitStrategyProgressive

All Implemented Interfaces:

IWaitStrategy

public class WaitStrategyProgressive
extends Object
implements IWaitStrategy

A Progressive Wait Strategy.

Has three levels of idling. Stays in each level for a configured number of iterations before entering the next level. Level 1 - No idling. Returns immediately. Stays in this level for level1Count iterations. Level 2 - Calls LockSupport.parkNanos(1). Stays in this level for level2Count iterations Level 3 - Calls Thread.sleep(). Stays in this level until wait situation changes.

The initial spin can be useful to prevent downstream bolt from repeatedly sleeping/parking when the upstream component is a bit relatively slower. Allows downstream bolt can enter deeper wait states only if the traffic to it appears to have reduced.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.storm.policy.IWaitStrategy

IWaitStrategy.WaitSituation

Constructor Summary

Constructors

Constructor and Description
WaitStrategyProgressive()

Method Summary

Modifier and Type	Method and Description
int	idle(int idleCounter) Implementations of this method should be thread-safe (preferably no side-effects and lock-free).
void	prepare(Map<String,Object> conf, IWaitStrategy.WaitSituation waitSituation)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.storm.policy.IWaitStrategy

createBackPressureWaitStrategy

Constructor Detail

WaitStrategyProgressive

public WaitStrategyProgressive()

Method Detail

prepare

public void prepare(Map<String,Object> conf,
                    IWaitStrategy.WaitSituation waitSituation)

Specified by:

prepare in interface IWaitStrategy

idle

public int idle(int idleCounter)
         throws InterruptedException

Description copied from interface: IWaitStrategy

Implementations of this method should be thread-safe (preferably no side-effects and lock-free).

Supports static or dynamic backoff. Dynamic backoff relies on idleCounter to estimate how long caller has been idling.

   int idleCounter = 0;  int consumeCount = consumeFromQ();  while (consumeCount==0) {  idleCounter = strategy.idle(idleCounter);  consumeCount = consumeFromQ();  }  

Specified by:

idle in interface IWaitStrategy

Parameters:

idleCounter - managed by the idle method until reset

Returns:

new counter value to be used on subsequent idle cycle

Throws:

InterruptedException