jna-master/contrib/platform/src/com/sun/jna/platform/win32/COM/util/ComThread.java
/* Copyright (c) 2014 Dr David H. Akehurst (itemis), All Rights Reserved
 *
 * The contents of this file is dual-licensed under 2
 * alternative Open Source/Free licenses: LGPL 2.1 or later and
 * Apache License 2.0. (starting with JNA version 4.0.0).
 *
 * You can freely decide which license you want to apply to
 * the project.
 *
 * You may obtain a copy of the LGPL License at:
 *
 * http://www.gnu.org/licenses/licenses.html
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "LGPL2.1".
 *
 * You may obtain a copy of the Apache License at:
 *
 * http://www.apache.org/licenses/
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "AL2.0".
 */
package com.sun.jna.platform.win32.COM.util;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import com.sun.jna.platform.win32.Ole32;
import com.sun.jna.platform.win32.WinNT;
import com.sun.jna.platform.win32.COM.COMUtils;

public class ComThread {
    private static ThreadLocal<Boolean> isCOMThread = new ThreadLocal<Boolean>();

    ExecutorService executor;
    Runnable firstTask;
    boolean requiresInitialisation;
    long timeoutMilliseconds;
    UncaughtExceptionHandler uncaughtExceptionHandler;

    public ComThread(final String threadName, long timeoutMilliseconds, UncaughtExceptionHandler uncaughtExceptionHandler) {
        this(threadName, timeoutMilliseconds, uncaughtExceptionHandler, Ole32.COINIT_MULTITHREADED);
    }

    public ComThread(final String threadName, long timeoutMilliseconds, UncaughtExceptionHandler uncaughtExceptionHandler, final int coinitialiseExFlag) {
        this.requiresInitialisation = true;
        this.timeoutMilliseconds = timeoutMilliseconds;
        this.uncaughtExceptionHandler = uncaughtExceptionHandler;
        this.firstTask = new Runnable() {
            @Override
            public void run() {
                try {
                    //If we do not use COINIT_MULTITHREADED, it is necessary to have
                    // a message loop see -
                    // [http://www.codeguru.com/cpp/com-tech/activex/apts/article.php/c5529/Understanding-COM-Apartments-Part-I.htm]
                    // [http://www.codeguru.com/cpp/com-tech/activex/apts/article.php/c5533/Understanding-COM-Apartments-Part-II.htm]
                    WinNT.HRESULT hr = Ole32.INSTANCE.CoInitializeEx(null, coinitialiseExFlag);
                    isCOMThread.set(true);
                    COMUtils.checkRC(hr);
                    ComThread.this.requiresInitialisation = false;
                } catch (Throwable t) {
                    ComThread.this.uncaughtExceptionHandler.uncaughtException(Thread.currentThread(), t);
                }
            }
        };
        executor = Executors.newSingleThreadExecutor(new ThreadFactory() {

            @Override
            public Thread newThread(Runnable r) {
                if (!ComThread.this.requiresInitialisation) {
                    // something has gone wrong!
                    throw new RuntimeException("ComThread executor has a problem.");
                }
                Thread thread = new Thread(r, threadName);
                //make sure this is a daemon thread, or it will stop JVM existing
                // if program does not call terminate();
                thread.setDaemon(true);

                thread.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
                    @Override
                    public void uncaughtException(Thread t, Throwable e) {
                        ComThread.this.requiresInitialisation = true;
                        ComThread.this.uncaughtExceptionHandler.uncaughtException(t, e);
                    }
                });

                return thread;
            }
        });

    }

    /**
     * Stop the COM Thread.
     *
     * @param timeoutMilliseconds
     *            number of milliseconds to wait for a clean shutdown before a
     *            forced shutdown is attempted
     */
    public void terminate(long timeoutMilliseconds) {
        try {

            executor.submit(new Runnable() {
                @Override
                public void run() {
                    Ole32.INSTANCE.CoUninitialize();
                }
            }).get(timeoutMilliseconds, TimeUnit.MILLISECONDS);

            executor.shutdown();

        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (TimeoutException e) {
            executor.shutdownNow();
        }
    }

    @Override
    protected void finalize() throws Throwable {
        if (!executor.isShutdown()) {
            this.terminate(100);
        }
    }

    static void setComThread(boolean value) {
        isCOMThread.set(value);
    }

    public <T> T execute(Callable<T> task) throws TimeoutException, InterruptedException, ExecutionException {
        // If the call is done on a COM thread, invoke directly
        // if the call comes from outside the invokation is dispatched
        // into the Dispatch Thread.
        Boolean comThread = isCOMThread.get();
        if (comThread == null) {
            comThread = false;
        }
        if (comThread) {
            try {
                return task.call();
            } catch (Exception ex) {
                throw new ExecutionException(ex);
            }
        } else {
            if (this.requiresInitialisation) {
                executor.execute(firstTask);
            }
            return executor.submit(task).get(this.timeoutMilliseconds, TimeUnit.MILLISECONDS);
        }
    }

}