1 /*
2  * Copyright 2019 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 androidx.camera.core.impl.utils.executor;
18 
19 import androidx.camera.core.CameraXThreads;
20 
21 import org.jspecify.annotations.NonNull;
22 
23 import java.util.Locale;
24 import java.util.concurrent.Executor;
25 import java.util.concurrent.ExecutorService;
26 import java.util.concurrent.Executors;
27 import java.util.concurrent.ThreadFactory;
28 import java.util.concurrent.atomic.AtomicInteger;
29 
30 /**
31  * A singleton executor which should be used for I/O tasks.
32  */
33 // TODO(b/115779693): Make this executor configurable
34 final class IoExecutor implements Executor {
35     private static volatile Executor sExecutor;
36 
37     private final ExecutorService mIoService =
38             Executors.newFixedThreadPool(
39                     2,
40                     new ThreadFactory() {
41                         private static final String THREAD_NAME_STEM =
42                                 CameraXThreads.TAG + "camerax_io_%d";
43 
44                         private final AtomicInteger mThreadId = new AtomicInteger(0);
45 
46                         @Override
47                         public Thread newThread(Runnable r) {
48                             Thread t = new Thread(r);
49                             t.setName(
50                                     String.format(
51                                             Locale.US,
52                                             THREAD_NAME_STEM,
53                                             mThreadId.getAndIncrement()));
54                             return t;
55                         }
56                     });
57 
getInstance()58     static Executor getInstance() {
59         if (sExecutor != null) {
60             return sExecutor;
61         }
62         synchronized (IoExecutor.class) {
63             if (sExecutor == null) {
64                 sExecutor = new IoExecutor();
65             }
66         }
67 
68         return sExecutor;
69     }
70 
71     @Override
execute(@onNull Runnable command)72     public void execute(@NonNull Runnable command) {
73         mIoService.execute(command);
74     }
75 }
76