org.apache.flink.streaming.connectors.kafka.internals

Class ExceptionProxy

java.lang.Object

org.apache.flink.streaming.connectors.kafka.internals.ExceptionProxy

@Internal
public class ExceptionProxy
extends Object

A proxy that communicates exceptions between threads. Typically used if an exception from a spawned thread needs to be recognized by the "parent" (spawner) thread.

The spawned thread would set the exception via reportError(Throwable). The parent would check (at certain points) for exceptions via checkAndThrowException(). Optionally, the parent can pass itself in the constructor to be interrupted as soon as an exception occurs.

 final ExceptionProxy errorProxy = new ExceptionProxy(Thread.currentThread());

 Thread subThread = new Thread() {

     public void run() {
         try {
             doSomething();
         } catch (Throwable t) {
             errorProxy.reportError(
         } finally {
             doSomeCleanup();
         }
     }
 };
 subThread.start();

 doSomethingElse();
 errorProxy.checkAndThrowException();

 doSomethingMore();
 errorProxy.checkAndThrowException();

 try {
     subThread.join();
 } catch (InterruptedException e) {
     errorProxy.checkAndThrowException();
     // restore interrupted status, if not caused by an exception
     Thread.currentThread().interrupt();
 }
 

Constructor Summary

Constructors

Constructor and Description
ExceptionProxy(Thread toInterrupt) Creates an exception proxy that interrupts the given thread upon report of an exception.

Method Summary

Modifier and Type	Method and Description
void	checkAndThrowException() Checks whether an exception has been set via reportError(Throwable).
void	reportError(Throwable t) Sets the exception and interrupts the target thread, if no other exception has occurred so far.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExceptionProxy

public ExceptionProxy(@Nullable
                      Thread toInterrupt)

Creates an exception proxy that interrupts the given thread upon report of an exception. The thread to interrupt may be null.

Parameters:

toInterrupt - The thread to interrupt upon an exception. May be null.

Method Detail

reportError

public void reportError(Throwable t)

Sets the exception and interrupts the target thread, if no other exception has occurred so far.

The exception is only set (and the interruption is only triggered), if no other exception was set before.

Parameters:

t - The exception that occurred

checkAndThrowException

public void checkAndThrowException()
                            throws Exception

Checks whether an exception has been set via reportError(Throwable). If yes, that exception if re-thrown by this method.

Throws:

Exception - This method re-throws the exception, if set.