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From Peter <j...@zeus.net.au>
Subject Re: TaskManager as an ExecutorService
Date Sat, 04 Jan 2014 23:51:16 GMT
The problem is with TaskManager's public api method Task.runAfter.  This is well documented
in River-344.

The fix requires changing every class that uses it

As a thread pool TaskManager is correct provided that no ordering dependencies exist between
tasks.

TaskManager doesn't compare to Doug Lee's ExecutorService implementations, it should be consigned
to history, lets clean our code up.

What configuration choice did we originally have anyway?  Any Executor you like as long as
it's TaskManager?

TaskManager is not part of our public api, it's an implementation detail in com.sun.*

Regards,

Peter.
----- Original message -----
> 
> I’d like you to make a reasonable case for why TaskManager needs to be
> replaced, requiring changes to many other classes that depend on
> TaskManager, rather than stating what the problem is with TaskManager
> and seeking to fix it, which would only affect TaskManager and not
> require modifying and then debugging other code.
> 
> Greg.
> 
> On Jan 4, 2014, at 5:53 AM, Peter Firmstone <jini@zeus.net.au> wrote:
> 
> > Would you like me to add this class, so that existing configurations
> > utilising a TaskManager can also be used?   This might be useful for
> > retaining backward compatibility with existing configurations?
> > 
> > Regards,
> > 
> > Peter.
> > 
> > 
> > /*
> > * Licensed to the Apache Software Foundation (ASF) under one
> > * or more contributor license agreements.   See the NOTICE file
> > * distributed with this work for additional information
> > * regarding copyright ownership. The ASF licenses this file
> > * to you under the Apache License, Version 2.0 (the
> > * "License"); you may not use this file except in compliance
> > * with the License. You may obtain a copy of the License at
> > *
> > *           http://www.apache.org/licenses/LICENSE-2.0
> > *
> > * Unless required by applicable law or agreed to in writing, software
> > * distributed under the License is distributed on an "AS IS" BASIS,
> > * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
> > implied. * See the License for the specific language governing
> > permissions and * limitations under the License.
> > */
> > 
> > package com.sun.jini.thread;
> > 
> > import com.sun.jini.thread.TaskManager.Task;
> > import java.util.List;
> > import java.util.concurrent.AbstractExecutorService;
> > import java.util.concurrent.ExecutorService;
> > import java.util.concurrent.RejectedExecutionException;
> > import java.util.concurrent.TimeUnit;
> > 
> > /**
> > *
> > * @author peter
> > */
> > public class TaskManagerWrapper extends AbstractExecutorService
> > implements ExecutorService {
> > 
> > private final TaskManager tm;
> > private final PosionPill pill;
> > private volatile boolean isShutdown;
> > 
> > public TaskManagerWrapper(TaskManager manager){
> > tm = manager;
> > isShutdown = false;
> > pill = new PosionPill(manager);
> > }
> > 
> > @Override
> > public void shutdown() {
> > isShutdown = true;
> > tm.add(pill);
> > }
> > 
> > @Override
> > public List<Runnable> shutdownNow() {
> > isShutdown = true;
> > tm.terminate();
> > return tm.getPending();
> > }
> > 
> > @Override
> > public boolean isShutdown() {
> > return isShutdown;
> > }
> > 
> > @Override
> > public boolean isTerminated() {
> > return isShutdown;
> > }
> > 
> > @Override
> > public boolean awaitTermination(long timeout, TimeUnit unit) throws
> > InterruptedException { long start = System.currentTimeMillis();
> > long duration = unit.toMillis(timeout);
> > synchronized (pill){
> > while (!pill.terminated){
> > wait(duration);
> > if (pill.terminated) return true;
> > long elapsed = System.currentTimeMillis() - start;
> > if (elapsed >= duration) return false;
> > duration = duration - elapsed;
> > }
> > }
> > return true; // pill was terminated.
> > }
> > 
> > @Override
> > public void execute(Runnable command) {
> > if (isShutdown) throw new RejectedExecutionException("TaskManager
> > terminated"); }
> > 
> > private static class PosionPill implements Task {
> > 
> > private final TaskManager tm;
> > boolean terminated;
> > 
> > PosionPill(TaskManager tm){
> > this.tm = tm;
> > terminated = false;
> > }
> > 
> > @Override
> > public boolean runAfter(List tasks, int size) {
> > if (!tasks.isEmpty()) return true; // Make sure we always run last.
> > return false;
> > }
> > 
> > @Override
> > public void run() {
> > tm.terminate(); // Bye.
> > synchronized (this){
> > terminated = true;
> > notifyAll();
> > }
> > }
> > 
> > }
> > 
> > }
> 


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