package com.bigdata.service.proxy;
import java.io.IOException;
import java.io.Serializable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
/**
* {@link Serializable} class wraps a {@link RemoteFuture} delegating
* methods through to the {@link Future} on the remote service while
* masquerading {@link IOException}s so that we can implement the
* {@link Future} API.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
* @param <T>
*/
public class ClientFuture<T> implements Future<T>, Serializable {
protected static final transient Logger log = Logger
.getLogger(ClientFuture.class);
/**
*
*/
private static final long serialVersionUID = -910518634373204705L;
private final RemoteFuture<T> proxy;
/**
* Set <code>true</code> once we know the Future to be done.
*/
private volatile transient boolean done = false;
/**
*
* @param proxy
* A proxy for the {@link RemoteFuture}.
*/
public ClientFuture(final RemoteFuture<T> proxy) {
if (proxy == null)
throw new IllegalArgumentException();
this.proxy = proxy;
}
/**
* Note: I have observed problems where an attempt to cancel a remote future
* fails when DGC is enabled. The stack trace looks like:
*
* <pre>
* java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.rmi.NoSuchObjectException: no such object in table
* at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:232)
* at java.util.concurrent.FutureTask.get(FutureTask.java:91)
* at com.bigdata.service.proxy.RemoteFutureImpl.get(RemoteFutureImpl.java:48)
* at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
* at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
* at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
* at java.lang.reflect.Method.invoke(Method.java:597)
* at net.jini.jeri.BasicInvocationDispatcher.invoke(BasicInvocationDispatcher.java:1126)
* at net.jini.jeri.BasicInvocationDispatcher.dispatch(BasicInvocationDispatcher.java:608)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$6.run(ObjectTable.java:597)
* at net.jini.export.ServerContext.doWithServerContext(ServerContext.java:103)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$Target.dispatch0(ObjectTable.java:595)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$Target.access$700(ObjectTable.java:212)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$5.run(ObjectTable.java:568)
* at java.security.AccessController.doPrivileged(Native Method)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$Target.dispatch(ObjectTable.java:565)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$Target.dispatch(ObjectTable.java:540)
* at com.sun.jini.jeri.internal.runtime.ObjectTable$RD.dispatch(ObjectTable.java:778)
* at net.jini.jeri.connection.ServerConnectionManager$Dispatcher.dispatch(ServerConnectionManager.java:148)
* at com.sun.jini.jeri.internal.mux.MuxServer$2.run(MuxServer.java:244)
* at java.security.AccessController.doPrivileged(Native Method)
* at com.sun.jini.jeri.internal.mux.MuxServer$1.run(MuxServer.java:241)
* at com.sun.jini.thread.ThreadPool$Worker.run(ThreadPool.java:136)
* at java.lang.Thread.run(Thread.java:619)
* at com.sun.jini.jeri.internal.runtime.Util.__________EXCEPTION_RECEIVED_FROM_SERVER__________(Util.java:108)
* at com.sun.jini.jeri.internal.runtime.Util.exceptionReceivedFromServer(Util.java:101)
* at net.jini.jeri.BasicInvocationHandler.unmarshalThrow(BasicInvocationHandler.java:1303)
* at net.jini.jeri.BasicInvocationHandler.invokeRemoteMethodOnce(BasicInvocationHandler.java:832)
* at net.jini.jeri.BasicInvocationHandler.invokeRemoteMethod(BasicInvocationHandler.java:659)
* at net.jini.jeri.BasicInvocationHandler.invoke(BasicInvocationHandler.java:528)
* at $Proxy8.get(Unknown Source)
* at com.bigdata.service.proxy.ClientFuture.get(ClientFuture.java:67)
* at com.bigdata.relation.rule.eval.pipeline.JoinMasterTask.awaitAll(JoinMasterTask.java:528)
* at com.bigdata.relation.rule.eval.pipeline.JoinMasterTask.call(JoinMasterTask.java:378)
* at com.bigdata.relation.rule.eval.pipeline.JoinMasterTask.call(JoinMasterTask.java:236)
* at com.bigdata.relation.rule.eval.AbstractStepTask.runOne(AbstractStepTask.java:331)
* at com.bigdata.relation.rule.eval.MutationTask.call(MutationTask.java:113)
* at com.bigdata.relation.rule.eval.MutationTask.call(MutationTask.java:55)
* at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
* at java.util.concurrent.FutureTask.run(FutureTask.java:138)
* at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
* at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
* at java.lang.Thread.run(Thread.java:619)
* Caused by: java.lang.RuntimeException: java.rmi.NoSuchObjectException: no such object in table
* at com.bigdata.service.proxy.ClientFuture.cancel(ClientFuture.java:48)
* at com.bigdata.relation.rule.eval.pipeline.DistributedJoinTask.cancelSinks(DistributedJoinTask.java:956)
* at com.bigdata.relation.rule.eval.pipeline.JoinTask.call(JoinTask.java:511)
* at com.bigdata.relation.rule.eval.pipeline.JoinTask.call(JoinTask.java:128)
* ... 5 more
* Caused by: java.rmi.NoSuchObjectException: no such object in table
* at net.jini.jeri.BasicObjectEndpoint.executeCall(BasicObjectEndpoint.java:420)
* at net.jini.jeri.BasicInvocationHandler.invokeRemoteMethodOnce(BasicInvocationHandler.java:806)
* at net.jini.jeri.BasicInvocationHandler.invokeRemoteMethod(BasicInvocationHandler.java:659)
* at net.jini.jeri.BasicInvocationHandler.invoke(BasicInvocationHandler.java:528)
* at $Proxy9.cancel(Unknown Source)
* at com.bigdata.service.proxy.ClientFuture.cancel(ClientFuture.java:46)
* ... 8 more
* </pre>
*
* This appears to be an RMI/DGC bug where the remote future is somehow
* garbage collected even though this class is holding a reference to its
* {@link RemoteFuture} proxy.
* <p>
* Since the remote future no longer exists we can assume that it is no
* longer running. Therefore, I have modified this method to log a warning
* and return <code>false</code> when this exception is thrown.
* <p>
* Note: I have also seen this problem where the stack trace involves
* <code>java.rmi.ConnectException</code>.
*
* @see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6181943
* @see http://archives.java.sun.com/cgi-bin/wa?A2=ind0509&L=rmi-users&P=617
* @see http://archives.java.sun.com/cgi-bin/wa?A2=ind0512&L=rmi-users&P=3747
* @see http://archives.java.sun.com/cgi-bin/wa?A2=ind0601&L=rmi-users&P=1985
*/
public boolean cancel(final boolean mayInterruptIfRunning) {
if (done) {
/*
* The task could not be cancelled (because it is already known to
* be done).
*/
return false;
}
try {
return proxy.cancel(mayInterruptIfRunning);
} catch (java.rmi.ConnectException ex) {
/*
* Log a warning.
*/
if (log.isEnabledFor(Level.WARN)) {
log.warn(ex.getLocalizedMessage());
}
/*
* Return false since not provably cancelled in response to this
* request.
*/
return false;
} catch (java.rmi.NoSuchObjectException ex) {
/*
* Log a warning.
*/
if (log.isEnabledFor(Level.WARN)) {
log.warn(ex.getLocalizedMessage());
}
/*
* Return false since not provably cancelled in response to this
* request.
*
* Note: if the object is gone, then a likely explanation is that
* the Future completed and has been finalized.
*/
return false;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public T get() throws InterruptedException, ExecutionException {
try {
final T t = proxy.get();
done = true;
return t;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public T get(long timeout, TimeUnit unit) throws InterruptedException,
ExecutionException, TimeoutException {
try {
final T t = proxy.get(timeout, unit);
done = true;
return t;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public boolean isCancelled() {
try {
final boolean t = proxy.isCancelled();
if (t) {
// If cancelled, then also done.
done = true;
}
return t;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public boolean isDone() {
try {
if (done)
return done;
done = proxy.isDone();
return done;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}