BackoffIdleStrategy (Agrona)

java.lang.Object
- org.agrona.concurrent.BackoffIdleStrategy

All Implemented Interfaces:

IdleStrategy
```
public final class BackoffIdleStrategy
extends Object
implements IdleStrategy
```
Idling strategy for threads when they have no work to do.
Spin for maxSpins, then Thread.yield() for maxYields, then LockSupport.parkNanos(long) on an exponential backoff to maxParkPeriodNs

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`ALIAS` Name to be returned from `alias()`.
`static long`	`DEFAULT_MAX_PARK_PERIOD_NS` Default maximum interval the strategy will park a thread.
`static long`	`DEFAULT_MAX_SPINS` Default number of times the strategy will spin without work before going to next state.
`static long`	`DEFAULT_MAX_YIELDS` Default number of times the strategy will yield without work before going to next state.
`static long`	`DEFAULT_MIN_PARK_PERIOD_NS` Default minimum interval the strategy will park a thread.
`protected long`	`maxParkPeriodNs` Max park period in nanoseconds.
`protected long`	`maxSpins` Max number of spins.
`protected long`	`maxYields` Max number of yields.
`protected long`	`minParkPeriodNs` Min park period in nanoseconds.
`protected static int`	`NOT_IDLE` Denotes a non-idle state.
`protected static int`	`PARKING` Denotes a parking state.
`protected long`	`parkPeriodNs` Park period in nanoseconds.
`protected static int`	`SPINNING` Denotes a spinning state.
`protected long`	`spins` Number of spins.
`protected int`	`state` Current state.
`protected static int`	`YIELDING` Denotes a yielding state.
`protected long`	`yields` Number of yields.

Constructor Summary

Constructors
Constructor and Description
`BackoffIdleStrategy()` Default constructor using `DEFAULT_MAX_SPINS`, `DEFAULT_MAX_YIELDS`, `DEFAULT_MIN_PARK_PERIOD_NS`, and `DEFAULT_MAX_YIELDS`.
`BackoffIdleStrategy(long maxSpins, long maxYields, long minParkPeriodNs, long maxParkPeriodNs)` Create a set of state tracking idle behavior

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`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.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - ALIAS
```
public static final String ALIAS
```
    Name to be returned from alias().
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_SPINS
```
public static final long DEFAULT_MAX_SPINS
```
    Default number of times the strategy will spin without work before going to next state.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_YIELDS
```
public static final long DEFAULT_MAX_YIELDS
```
    Default number of times the strategy will yield without work before going to next state.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MIN_PARK_PERIOD_NS
```
public static final long DEFAULT_MIN_PARK_PERIOD_NS
```
    Default minimum interval the strategy will park a thread.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_PARK_PERIOD_NS
```
public static final long DEFAULT_MAX_PARK_PERIOD_NS
```
    Default maximum interval the strategy will park a thread.
    
    See Also:
    
    Constant Field Values
  - NOT_IDLE
```
protected static final int NOT_IDLE
```
    Denotes a non-idle state.
    
    See Also:
    
    Constant Field Values
  - SPINNING
```
protected static final int SPINNING
```
    Denotes a spinning state.
    
    See Also:
    
    Constant Field Values
  - YIELDING
```
protected static final int YIELDING
```
    Denotes a yielding state.
    
    See Also:
    
    Constant Field Values
  - PARKING
```
protected static final int PARKING
```
    Denotes a parking state.
    
    See Also:
    
    Constant Field Values
  - maxSpins
```
protected final long maxSpins
```
    Max number of spins.
  - maxYields
```
protected final long maxYields
```
    Max number of yields.
  - minParkPeriodNs
```
protected final long minParkPeriodNs
```
    Min park period in nanoseconds.
  - maxParkPeriodNs
```
protected final long maxParkPeriodNs
```
    Max park period in nanoseconds.
  - state
```
protected int state
```
    Current state.
  - spins
```
protected long spins
```
    Number of spins.
  - yields
```
protected long yields
```
    Number of yields.
  - parkPeriodNs
```
protected long parkPeriodNs
```
    Park period in nanoseconds.
- Constructor Detail
  - BackoffIdleStrategy
```
public BackoffIdleStrategy()
```
    Default constructor using DEFAULT_MAX_SPINS, DEFAULT_MAX_YIELDS, DEFAULT_MIN_PARK_PERIOD_NS, and DEFAULT_MAX_YIELDS.
  - BackoffIdleStrategy
```
public BackoffIdleStrategy(long maxSpins,
                           long maxYields,
                           long minParkPeriodNs,
                           long maxParkPeriodNs)
```
    Create a set of state tracking idle behavior
    
    Parameters:
    
    maxSpins - to perform before moving to Thread.yield()
    
    maxYields - to perform before moving to LockSupport.parkNanos(long)
    
    minParkPeriodNs - to use when initiating parking
    
    maxParkPeriodNs - to use when parking
- Method Detail
  - idle
```
public 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());
 }
 
 
```
    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

Class BackoffIdleStrategy

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ALIAS

DEFAULT_MAX_SPINS

DEFAULT_MAX_YIELDS

DEFAULT_MIN_PARK_PERIOD_NS

DEFAULT_MAX_PARK_PERIOD_NS

NOT_IDLE

SPINNING

YIELDING

PARKING

maxSpins

maxYields

minParkPeriodNs

maxParkPeriodNs

state

spins

yields

parkPeriodNs

Constructor Detail

BackoffIdleStrategy

BackoffIdleStrategy

Method Detail

idle

idle

reset

alias

toString