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
17package com.android.camera.device;
18
19import com.android.camera.async.Lifetime;
20import com.android.camera.async.SafeCloseable;
21import com.google.common.util.concurrent.ListenableFuture;
22import com.google.common.util.concurrent.SettableFuture;
23
24import java.util.concurrent.atomic.AtomicBoolean;
25
26import 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
33public 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