org.apache.hadoop.hbase.procedure2

Class ProcedureEvent<T>

java.lang.Object

org.apache.hadoop.hbase.procedure2.ProcedureEvent<T>

Direct Known Subclasses:

RegionStateNode.AssignmentProcedureEvent

@InterfaceAudience.Private
public class ProcedureEvent<T>
extends Object

Basic ProcedureEvent that contains an "object", which can be a description or a reference to the resource to wait on, and a queue for suspended procedures.

Field Summary

Fields

Modifier and Type	Field and Description
private static org.slf4j.Logger	LOG
private T	object
private boolean	ready
private ProcedureDeque	suspendedProcedures

Constructor Summary

Constructors

Constructor and Description
ProcedureEvent(T object)

Method Summary

Modifier and Type	Method and Description
ProcedureDeque	getSuspendedProcedures() Access to suspendedProcedures is 'synchronized' on this object, but it's fine to return it here for tests.
boolean	isReady()
void	suspend() Mark the event as not ready.
boolean	suspendIfNotReady(Procedure proc) Returns true if event is not ready and adds procedure to suspended queue, else returns false.
String	toString()
void	wake(AbstractProcedureScheduler procedureScheduler) Wakes up the suspended procedures by pushing them back into scheduler queues and sets the event as ready.
static void	wakeEvents(AbstractProcedureScheduler scheduler, ProcedureEvent... events) Wakes up all the given events and puts the procedures waiting on them back into ProcedureScheduler queues.
boolean	wakeIfSuspended(AbstractProcedureScheduler procedureScheduler, Procedure<?> proc) Wakes up the suspended procedures only if the given proc is waiting on this event.
(package private) void	wakeInternal(AbstractProcedureScheduler procedureScheduler) Only to be used by ProcedureScheduler implementations.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

object

private final T object

ready

private boolean ready

suspendedProcedures

private ProcedureDeque suspendedProcedures

Constructor Detail

ProcedureEvent

public ProcedureEvent(T object)

Method Detail

isReady

public boolean isReady()

suspendIfNotReady

public boolean suspendIfNotReady(Procedure proc)

Returns true if event is not ready and adds procedure to suspended queue, else returns false.

suspend

public void suspend()

Mark the event as not ready.

wake

public void wake(AbstractProcedureScheduler procedureScheduler)

Wakes up the suspended procedures by pushing them back into scheduler queues and sets the event as ready. See wakeInternal(AbstractProcedureScheduler) for why this is not synchronized.

wakeIfSuspended

public boolean wakeIfSuspended(AbstractProcedureScheduler procedureScheduler,
                               Procedure<?> proc)

Wakes up the suspended procedures only if the given proc is waiting on this event.

Mainly used by region assignment to reject stale OpenRegionProcedure/CloseRegionProcedure. Use with caution as it will cause performance issue if there are lots of procedures waiting on the event.

wakeEvents

public static void wakeEvents(AbstractProcedureScheduler scheduler,
                              ProcedureEvent... events)

Wakes up all the given events and puts the procedures waiting on them back into ProcedureScheduler queues.

wakeInternal

void wakeInternal(AbstractProcedureScheduler procedureScheduler)

Only to be used by ProcedureScheduler implementations. Reason: To wake up multiple events, locking sequence is schedLock --> synchronized (event) To wake up an event, both schedLock() and synchronized(event) are required. The order is schedLock() --> synchronized(event) because when waking up multiple events simultaneously, we keep the scheduler locked until all procedures suspended on these events have been added back to the queue (Maybe it's not required? Evaluate!) To avoid deadlocks, we want to keep the locking order same even when waking up single event. That's why, wake(AbstractProcedureScheduler) above uses the same code path as used when waking up multiple events. Access should remain package-private.

getSuspendedProcedures

public ProcedureDeque getSuspendedProcedures()

Access to suspendedProcedures is 'synchronized' on this object, but it's fine to return it here for tests.

toString

public String toString()

Overrides:

toString in class Object