Issue #431: Canceling background threads (after timeout, or after user action, e.g new treeitem selected) fixed + small fixes

trunk/src/com/jpexs/helpers/CancellableWorker.java

@@ -0,0 +1,128 @@
+/*
+ *  Copyright (C) 2010-2013 JPEXS
+ * 
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ * 
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ * 
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.jpexs.helpers;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.FutureTask;
+import java.util.concurrent.RunnableFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/**
+ *
+ * @author JPEXS
+ */
+public abstract class CancellableWorker<T> implements RunnableFuture<T> {
+    
+    private static final ExecutorService THREAD_POOL = Executors.newCachedThreadPool();
+    private static List<CancellableWorker> workers = Collections.synchronizedList(new ArrayList<CancellableWorker>());
+    private final FutureTask<T> future;
+    
+    public CancellableWorker() {
+        super();
+        Callable<T> callable =
+                new Callable<T>() {
+                    @Override
+                    public T call() throws Exception {
+                        return doInBackground();
+                    }
+                };
+
+        future = new FutureTask<T>(callable) {
+                       @Override
+                       protected void done() {
+                           workerDone();
+                       }
+                   };
+    }
+
+    protected abstract T doInBackground() throws Exception;
+
+    @Override
+    public final void run() {
+        workers.add(this);
+        future.run();
+    }
+
+    protected void done() {
+    }
+    
+    public final void execute() {
+        THREAD_POOL.execute(this);
+    }
+
+    @Override
+    public final boolean cancel(boolean mayInterruptIfRunning) {
+        return future.cancel(mayInterruptIfRunning);
+    }
+
+    @Override
+    public final boolean isCancelled() {
+        return future.isCancelled();
+    }
+
+    @Override
+    public final boolean isDone() {
+        return future.isDone();
+    }
+
+    @Override
+    public final T get() throws InterruptedException, ExecutionException {
+        return future.get();
+    }
+
+    @Override
+    public final T get(long timeout, TimeUnit unit) throws InterruptedException,
+            ExecutionException, TimeoutException {
+        return future.get(timeout, unit);
+    }
+
+    private void workerDone() {
+        workers.remove(this);
+        done();
+    }
+
+    public static <T> T call(final Callable<T> c, long timeout, TimeUnit timeUnit) throws InterruptedException, ExecutionException, TimeoutException {
+        CancellableWorker<T> worker = new CancellableWorker<T>() {
+
+            @Override
+            protected T doInBackground() throws Exception {
+                return c.call();
+            }
+        };
+        try {
+            worker.execute();
+            return worker.get(timeout, timeUnit);
+        } finally {
+            worker.cancel(true);
+        }
+    }
+    
+    public static void cancelBackgroundThreads() {
+        List<CancellableWorker> oldWorkers = workers;
+        workers = new ArrayList<>();
+        for (CancellableWorker worker : oldWorkers) {
+            worker.cancel(true);
+        }
+    }
+}