org.apache.hadoop.hbase
Class Chore

java.lang.Object
  org.apache.hadoop.hbase.util.HasThread
      org.apache.hadoop.hbase.Chore

All Implemented Interfaces:

Runnable

@InterfaceAudience.Private
public abstract class Chore
extends HasThread

Chore is a task performed on a period in hbase. The chore is run in its own thread. This base abstract class provides while loop and sleeping facility. If an unhandled exception, the threads exit is logged. Implementers just need to add checking if there is work to be done and if so, do it. Its the base of most of the chore threads in hbase.

Don't subclass Chore if the task relies on being woken up for something to do, such as an entry being added to a queue, etc.

Field Summary

protected Stoppable

stopper

Constructor Summary

protected	Chore() This constructor is for test only.
	Chore(String name, int p, Stoppable stopper)

Method Summary

protected abstract void	chore() Look for chores.
void	choreForTesting()
protected void	cleanup() Called when the chore has completed, allowing subclasses to cleanup any extra overhead
protected boolean	initialChore() Override to run a task before we start looping.
void	run()
protected void	sleep() Sleep for period.
void	triggerNow() If the thread is currently sleeping, trigger the core to happen immediately.

Methods inherited from class org.apache.hadoop.hbase.util.HasThread

getName, getThread, interrupt, isAlive, isInterrupted, join, join, join, setDaemon, setName, setPriority, setUncaughtExceptionHandler, start

Methods inherited from class java.lang.Object

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

Field Detail

stopper

protected final Stoppable stopper

Constructor Detail

Chore

public Chore(String name,
             int p,
             Stoppable stopper)

Parameters:

p - Period at which we should run. Will be adjusted appropriately should we find work and it takes time to complete.

stopper - When Stoppable.isStopped() is true, this thread will cleanup and exit cleanly.

Chore

protected Chore()

This constructor is for test only. It allows to create an object and to call chore() on it. There is no sleeper nor stoppable.

Method Detail

run

public void run()

Specified by:

run in interface Runnable

Specified by:

run in class HasThread

See Also:

Thread.run()

triggerNow

public void triggerNow()

If the thread is currently sleeping, trigger the core to happen immediately. If it's in the middle of its operation, will begin another operation immediately after finishing this one.

choreForTesting

public void choreForTesting()

initialChore

protected boolean initialChore()

Override to run a task before we start looping.

Returns:

true if initial chore was successful

chore

protected abstract void chore()

Look for chores. If any found, do them else just return.

sleep

protected void sleep()

Sleep for period.

cleanup

protected void cleanup()

Called when the chore has completed, allowing subclasses to cleanup any extra overhead