sirius.kernel.async

Class BackgroundLoop

java.lang.Object

sirius.kernel.async.BackgroundLoop

Direct Known Subclasses:

DelayLine

public abstract class BackgroundLoop
extends Object

Represents a background worker which is constantly processing a set of tasks (if available).

Often a system needs all kinds of cleanup jobs which run constantly in the background, without ever affecting the system performance.

Therefore a BackgroundLoop is called repeatedly to perform some work. If no work is available the loop automatically throttles itself to a certain frequency so that no system resources are wasted.

By default the doWork() method is at most executed every ten seconds. The can be changed by overriding maxCallFrequency().

Note that subclasses must wear an Register annotation like this: @Register(classes = BackgroundLoop.class) to be visible to the framework.

Constructor Summary

Constructors

Constructor and Description
BackgroundLoop()

Method Summary

Modifier and Type	Method and Description
protected String	determineExecutor() Determines the executor (thread pool) used to execute the actual work.
protected abstract void	doWork() Executes the actual work.
String	getExecutionInfo() Contains the timestamp and duration of the last execution for monitoring purposes.
abstract String	getName() Returns the name of the loop.
protected void	loop() Calls executeWork() in the determined executor.
protected double	maxCallFrequency() Determines the maximal call frequency of doWork() in Hertz (ticks per second).
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

BackgroundLoop

public BackgroundLoop()

Method Detail

getName

@Nonnull
public abstract String getName()

Returns the name of the loop.

Returns:

the name of the loop for reporting and logging

doWork

protected abstract void doWork()
                        throws Exception

Executes the actual work.

Throws:

Exception - in case of any error. The outer loop has a catch all rule to log exceptions.

maxCallFrequency

protected double maxCallFrequency()

Determines the maximal call frequency of doWork() in Hertz (ticks per second).

Returns:

the maximal call frequency in Hertz.

determineExecutor

@Nonnull
protected String determineExecutor()

Determines the executor (thread pool) used to execute the actual work.

By default the background executor is used.

Returns:

the name of the executor to use when calling doWork.

loop

protected void loop()

Calls executeWork() in the determined executor.

This is kind of the main loop, as executeWork() will call loop() once the computation (doWork() is finished. Using ExecutionBuilder.frequency(Object, double) this is limited to the call frequency as determined by maxCallFrequency().

toString

public String toString()

Overrides:

toString in class Object

getExecutionInfo

public String getExecutionInfo()

Contains the timestamp and duration of the last execution for monitoring purposes.

Returns:

a formatted timestamp and duration for logging and monitoring purposes.