org.apache.hadoop.hbase.errorhandling

Class ForeignExceptionDispatcher

java.lang.Object

org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher

All Implemented Interfaces:

ForeignExceptionListener, ForeignExceptionSnare

@InterfaceAudience.Private
public class ForeignExceptionDispatcher
extends Object
implements ForeignExceptionListener, ForeignExceptionSnare

The dispatcher acts as the state holding entity for foreign error handling. The first exception received by the dispatcher get passed directly to the listeners. Subsequent exceptions are dropped.

If there are multiple dispatchers that are all in the same foreign exception monitoring group, ideally all these monitors are "peers" -- any error on one dispatcher should get propagated to all others (via rpc, or some other mechanism). Due to racing error conditions the exact reason for failure may be different on different peers, but the fact that they are in error state should eventually hold on all.

This is thread-safe and must be because this is expected to be used to propagate exceptions from foreign threads.

Field Summary

Fields

Modifier and Type	Field and Description
private ForeignException	exception
protected List<ForeignExceptionListener>	listeners
private static org.slf4j.Logger	LOG
protected String	name

Constructor Summary

Constructors

Constructor and Description
ForeignExceptionDispatcher()
ForeignExceptionDispatcher(String name)

Method Summary

Modifier and Type	Method and Description
void	addListener(ForeignExceptionListener errorable) Listen for failures to a given process.
private void	dispatch(ForeignException e) Sends an exception to all listeners.
ForeignException	getException() Get the value of the captured exception.
String	getName()
boolean	hasException() Non-exceptional form of ForeignExceptionSnare.rethrowException().
void	receive(ForeignException e) Receive a ForeignException.
void	rethrowException() Rethrow an exception currently held by the ForeignExceptionSnare.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

name

protected final String name

listeners

protected final List<ForeignExceptionListener> listeners

exception

private ForeignException exception

Constructor Detail

ForeignExceptionDispatcher

public ForeignExceptionDispatcher(String name)

ForeignExceptionDispatcher

public ForeignExceptionDispatcher()

Method Detail

getName

public String getName()

receive

public void receive(ForeignException e)

Description copied from interface: ForeignExceptionListener

Receive a ForeignException.

Implementers must ensure that this method is thread-safe.

Specified by:

receive in interface ForeignExceptionListener

Parameters:

e - exception causing the error. Implementations must accept and handle null here.

rethrowException

public void rethrowException()
                      throws ForeignException

Description copied from interface: ForeignExceptionSnare

Rethrow an exception currently held by the ForeignExceptionSnare. If there is no exception this is a no-op

Specified by:

rethrowException in interface ForeignExceptionSnare

Throws:

ForeignException - all exceptions from remote sources are procedure exceptions

hasException

public boolean hasException()

Description copied from interface: ForeignExceptionSnare

Non-exceptional form of ForeignExceptionSnare.rethrowException(). Checks to see if any process to which the exception checkers is bound has created an error that would cause a failure.

Specified by:

hasException in interface ForeignExceptionSnare

Returns:

true if there has been an error,false otherwise

getException

public ForeignException getException()

Description copied from interface: ForeignExceptionSnare

Get the value of the captured exception.

Specified by:

getException in interface ForeignExceptionSnare

Returns:

the captured foreign exception or null if no exception captured.

dispatch

private void dispatch(ForeignException e)

Sends an exception to all listeners.

Parameters:

e - ForeignException containing the cause. Can be null.

addListener

public void addListener(ForeignExceptionListener errorable)

Listen for failures to a given process. This method should only be used during initialization and not added to after exceptions are accepted.

Parameters:

errorable - listener for the errors. may be null.