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      1 /*
      2  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
      3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
      4  *
      5  * This code is free software; you can redistribute it and/or modify it
      6  * under the terms of the GNU General Public License version 2 only, as
      7  * published by the Free Software Foundation.  Oracle designates this
      8  * particular file as subject to the "Classpath" exception as provided
      9  * by Oracle in the LICENSE file that accompanied this code.
     10  *
     11  * This code is distributed in the hope that it will be useful, but WITHOUT
     12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14  * version 2 for more details (a copy is included in the LICENSE file that
     15  * accompanied this code).
     16  *
     17  * You should have received a copy of the GNU General Public License version
     18  * 2 along with this work; if not, write to the Free Software Foundation,
     19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
     20  *
     21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
     22  * or visit www.oracle.com if you need additional information or have any
     23  * questions.
     24  */
     25 
     26 package sun.nio.ch;
     27 
     28 import java.util.concurrent.Future;
     29 import java.util.concurrent.TimeUnit;
     30 import java.util.concurrent.ExecutionException;
     31 import java.io.IOException;
     32 
     33 /**
     34  * A Future representing the result of an I/O operation that has already
     35  * completed.
     36  */
     37 
     38 final class CompletedFuture<V> implements Future<V> {
     39     private final V result;
     40     private final Throwable exc;
     41 
     42     private CompletedFuture(V result, Throwable exc) {
     43         this.result = result;
     44         this.exc = exc;
     45     }
     46 
     47     static <V> CompletedFuture<V> withResult(V result) {
     48         return new CompletedFuture<V>(result, null);
     49     }
     50 
     51     static <V> CompletedFuture<V> withFailure(Throwable exc) {
     52         // exception must be IOException or SecurityException
     53         if (!(exc instanceof IOException) && !(exc instanceof SecurityException))
     54             exc = new IOException(exc);
     55         return new CompletedFuture<V>(null, exc);
     56     }
     57 
     58     static <V> CompletedFuture<V> withResult(V result, Throwable exc) {
     59         if (exc == null) {
     60             return withResult(result);
     61         } else {
     62             return withFailure(exc);
     63         }
     64     }
     65 
     66     @Override
     67     public V get() throws ExecutionException {
     68         if (exc != null)
     69             throw new ExecutionException(exc);
     70         return result;
     71     }
     72 
     73     @Override
     74     public V get(long timeout, TimeUnit unit) throws ExecutionException {
     75         if (unit == null)
     76             throw new NullPointerException();
     77         if (exc != null)
     78             throw new ExecutionException(exc);
     79         return result;
     80     }
     81 
     82     @Override
     83     public boolean isCancelled() {
     84         return false;
     85     }
     86 
     87     @Override
     88     public boolean isDone() {
     89         return true;
     90     }
     91 
     92     @Override
     93     public boolean cancel(boolean mayInterruptIfRunning) {
     94         return false;
     95     }
     96 }
     97