org.apache.hadoop.hbase

Class ScheduledChore

java.lang.Object

org.apache.hadoop.hbase.ScheduledChore

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

BalancerChore, CatalogJanitor, CleanerChore, ClusterStatusChore, ClusterStatusPublisher, HealthCheckChore, HRegionServer.MovedRegionsCleaner, ReplicationZKLockCleanerChore, StorefileRefresherChore

@InterfaceAudience.Private
public abstract class ScheduledChore
extends Object
implements Runnable

ScheduledChore is a task performed on a period in hbase. ScheduledChores become active once scheduled with a ChoreService via ChoreService.scheduleChore(ScheduledChore). The chore is run in a ScheduledThreadPoolExecutor and competes with other ScheduledChores for access to the threads in the core thread pool. If an unhandled exception occurs, the chore cancellation is logged. Implementers should consider whether or not the Chore will be able to execute within the defined period. It is bad practice to define a ScheduledChore whose execution time exceeds its period since it will try to hog one of the threads in the ChoreService's thread pool.

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

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ScheduledChore() This constructor is for test only.
	ScheduledChore(String name, Stoppable stopper, int period)
	ScheduledChore(String name, Stoppable stopper, int period, long initialDelay)
	ScheduledChore(String name, Stoppable stopper, int period, long initialDelay, TimeUnit unit)

Method Summary

Methods

Modifier and Type	Method and Description
void	cancel()
void	cancel(boolean mayInterruptIfRunning)
protected abstract void	chore() The task to execute on each scheduled execution of the Chore
void	choreForTesting()
protected void	cleanup() Override to run cleanup tasks when the Chore encounters an error and must stop running
long	getInitialDelay()
String	getName()
int	getPeriod()
Stoppable	getStopper()
TimeUnit	getTimeUnit()
protected boolean	initialChore() Override to run a task before we start looping.
boolean	isInitialChoreComplete()
boolean	isScheduled()
void	run()
String	toString()
boolean	triggerNow()

Methods inherited from class java.lang.Object

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

Constructor Detail

ScheduledChore

protected ScheduledChore()

This constructor is for test only. It allows us to create an object and to call chore() on it.

ScheduledChore

public ScheduledChore(String name,
              Stoppable stopper,
              int period)

Parameters:

name - Name assigned to Chore. Useful for identification amongst chores of the same type

stopper - When Stoppable.isStopped() is true, this chore will cancel and cleanup

period - Period in millis with which this Chore repeats execution when scheduled.

ScheduledChore

public ScheduledChore(String name,
              Stoppable stopper,
              int period,
              long initialDelay)

Parameters:

name - Name assigned to Chore. Useful for identification amongst chores of the same type

stopper - When Stoppable.isStopped() is true, this chore will cancel and cleanup

period - Period in millis with which this Chore repeats execution when scheduled.

initialDelay - Delay before this Chore begins to execute once it has been scheduled. A value of 0 means the chore will begin to execute immediately. Negative delays are invalid and will be corrected to a value of 0.

ScheduledChore

public ScheduledChore(String name,
              Stoppable stopper,
              int period,
              long initialDelay,
              TimeUnit unit)

Parameters:

name - Name assigned to Chore. Useful for identification amongst chores of the same type

stopper - When Stoppable.isStopped() is true, this chore will cancel and cleanup

period - Period in Timeunit unit with which this Chore repeats execution when scheduled.

initialDelay - Delay in Timeunit unit before this Chore begins to execute once it has been scheduled. A value of 0 means the chore will begin to execute immediately. Negative delays are invalid and will be corrected to a value of 0.

unit - The unit that is used to measure period and initialDelay

Method Detail

run

public void run()

Specified by:

run in interface Runnable

See Also:

Thread.run()

triggerNow

public boolean triggerNow()

Returns:

false when the Chore is not currently scheduled with a ChoreService

cancel

public void cancel()

cancel

public void cancel(boolean mayInterruptIfRunning)

getName

public String getName()

getStopper

public Stoppable getStopper()

getPeriod

public int getPeriod()

Returns:

period to execute chore in getTimeUnit() units

getInitialDelay

public long getInitialDelay()

Returns:

initial delay before executing chore in getTimeUnit() units

getTimeUnit

public TimeUnit getTimeUnit()

isInitialChoreComplete

public boolean isInitialChoreComplete()

isScheduled

public boolean isScheduled()

Returns:

true when this Chore is scheduled with a ChoreService

choreForTesting

public void choreForTesting()

chore

protected abstract void chore()

The task to execute on each scheduled execution of the Chore

initialChore

protected boolean initialChore()

Override to run a task before we start looping.

Returns:

true if initial chore was successful

cleanup

protected void cleanup()

Override to run cleanup tasks when the Chore encounters an error and must stop running

toString

public String toString()

Overrides:

toString in class Object