Package org.agrona.concurrent

Class BusySpinIdleStrategy

java.lang.Object

org.agrona.concurrent.BusySpinIdleStrategy

All Implemented Interfaces:

IdleStrategy

public final class BusySpinIdleStrategy
extends Object
implements IdleStrategy

Busy spin strategy targeted at lowest possible latency. This strategy will monopolise a thread to achieve the lowest possible latency. Useful for creating bubbles in the execution pipeline of tight busy spin loops with no other logic than status checks on progress.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	ALIAS	Name to be returned from alias().
static final BusySpinIdleStrategy	INSTANCE	As there is no instance state then this object can be used to save on allocation.

Constructor Summary

Constructors

Constructor	Description
BusySpinIdleStrategy()	Create a new instance.

Method Summary

Modifier and Type	Method	Description
String	alias()	Simple name by which the strategy can be identified.
void	idle()	Perform current idle action (e.g.
void	idle(int workCount)	Note: this implementation will result in no safepoint poll once inlined.
void	reset()	Reset the internal state in preparation for entering an idle state again.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

ALIAS

public static final String ALIAS

Name to be returned from alias().

See Also:

• Constant Field Values

INSTANCE

public static final BusySpinIdleStrategy INSTANCE

As there is no instance state then this object can be used to save on allocation.

Constructor Details

BusySpinIdleStrategy

public BusySpinIdleStrategy()

Create a new instance.

Method Details

idle

public void idle(int workCount)

Note: this implementation will result in no safepoint poll once inlined.

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());
 }
 
 

Specified by:

idle in interface IdleStrategy

Parameters:

workCount - performed in last duty cycle.

idle

public void idle()

Perform current idle action (e.g. nothing/yield/sleep). To be used in conjunction with IdleStrategy.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();
 }
 
 

Specified by:

idle in interface IdleStrategy

reset

public void reset()

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

Specified by:

reset in interface IdleStrategy

alias

public String alias()

Simple name by which the strategy can be identified.

Specified by:

alias in interface IdleStrategy

Returns:

simple name by which the strategy can be identified.

toString

public String toString()

Overrides:

toString in class Object