org.agrona.concurrent

Interface IdleStrategy

All Known Implementing Classes:

BackoffIdleStrategy, BusySpinIdleStrategy, ControllableIdleStrategy, NoOpIdleStrategy, SleepingIdleStrategy, SleepingMillisIdleStrategy, YieldingIdleStrategy

public interface IdleStrategy

Idle strategy for use by threads when they do not have work to do.

Note regarding implementor state

Some implementations are known to be stateful, please note that you cannot safely assume implementations to be stateless. Where implementations are stateful it is recommended that implementation state is padded to avoid false sharing.

Note regarding potential for TTSP(Time To Safe Point) issues

If the caller spins in a 'counted' loop, and the implementation does not include a safepoint poll this may cause a TTSP (Time To SafePoint) problem. If this is the case for your application you can solve it by preventing the idle method from being inlined by using a Hotspot compiler command as a JVM argument e.g: -XX:CompileCommand=dontinline,org.agrona.concurrent.NoOpIdleStrategy::idle

Method Summary

Modifier and Type	Method and Description
default String	alias() Simple name by which the strategy can be identified.
void	idle() Perform current idle action (e.g.
void	idle(int workCount) Perform current idle action (e.g.
void	reset() Reset the internal state in preparation for entering an idle state again.

Method Detail

idle

void idle(int workCount)

Perform current idle action (e.g. nothing/yield/sleep). This method signature expects users to call into it on every work 'cycle'. The implementations may use the indication "workCount > 0" to reset internal backoff state. This method works well with 'work' APIs which follow the following rules:

• 'work' returns a value larger than 0 when some work has been done
• 'work' returns 0 when no work has been done
• 'work' may return error codes which are less than 0, but which amount to no work has been done

Callers are expected to follow this pattern:

 
 while (isRunning)
 {
     idleStrategy.idle(doWork());
 }
 
 

Parameters:

workCount - performed in last duty cycle.

idle

void idle()

Perform current idle action (e.g. nothing/yield/sleep). To be used in conjunction with reset() to clear internal state when idle period is over (or before it begins). Callers are expected to follow this pattern:

 
 while (isRunning)
 {
   if (!hasWork())
   {
     idleStrategy.reset();
     while (!hasWork())
     {
       if (!isRunning)
       {
         return;
       }
       idleStrategy.idle();
     }
   }
   doWork();
 }
 
 

reset

void reset()

Reset the internal state in preparation for entering an idle state again.

alias

default String alias()

Simple name by which the strategy can be identified.

Returns:

simple name by which the strategy can be identified.