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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.camera.device;
     18 
     19 import com.android.camera.async.Lifetime;
     20 import com.android.camera.async.SafeCloseable;
     21 import com.google.common.util.concurrent.ListenableFuture;
     22 import com.google.common.util.concurrent.SettableFuture;
     23 
     24 import java.util.concurrent.atomic.AtomicBoolean;
     25 
     26 import javax.annotation.concurrent.ThreadSafe;
     27 
     28 /**
     29  * ThreadSafe class to deal with the combined future and lifetime
     30  * for a single device request.
     31  */
     32 @ThreadSafe
     33 public class SingleDeviceRequest<TDevice> implements SafeCloseable {
     34     private final SettableFuture<TDevice> mFuture;
     35     private final Lifetime mLifetime;
     36     private final AtomicBoolean mIsClosed;
     37 
     38     public SingleDeviceRequest(Lifetime lifetime) {
     39         mLifetime = lifetime;
     40         mFuture = SettableFuture.create();
     41         mIsClosed = new AtomicBoolean(false);
     42     }
     43 
     44     /**
     45      * Return the future instance for this request.
     46      */
     47     public ListenableFuture<TDevice> getFuture() {
     48         return mFuture;
     49     }
     50 
     51     /**
     52      * Return the lifetime instance for this request.
     53      */
     54     public Lifetime getLifetime() {
     55         return mLifetime;
     56     }
     57 
     58     /**
     59      * If the future has not been set, set the value.
     60      */
     61     public boolean set(TDevice device) {
     62         if (!mIsClosed.get()) {
     63             return mFuture.set(device);
     64         } else {
     65             return false;
     66         }
     67     }
     68 
     69     public boolean isClosed() {
     70         return mIsClosed.get();
     71     }
     72 
     73     public void closeWithException(Throwable throwable) {
     74         if (!mIsClosed.getAndSet(true)) {
     75             mFuture.setException(throwable);
     76             mLifetime.close();
     77         }
     78     }
     79 
     80     @Override
     81     public void close() {
     82         if (!mIsClosed.getAndSet(true)) {
     83             mFuture.cancel(true /* mayInterruptIfRunning */);
     84             mLifetime.close();
     85         }
     86     }
     87 }
     88