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      1 /*
      2  * Copyright (C) 2011 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.dialer.common.concurrent;
     18 
     19 import android.os.AsyncTask;
     20 import android.support.annotation.MainThread;
     21 import com.android.dialer.common.Assert;
     22 import java.util.concurrent.Executor;
     23 
     24 /**
     25  * Factory methods for creating AsyncTaskExecutors.
     26  *
     27  * <p>All of the factory methods on this class check first to see if you have set a static {@link
     28  * AsyncTaskExecutorFactory} set through the {@link #setFactoryForTest(AsyncTaskExecutorFactory)}
     29  * method, and if so delegate to that instead, which is one way of injecting dependencies for
     30  * testing classes whose construction cannot be controlled such as {@link android.app.Activity}.
     31  */
     32 public final class AsyncTaskExecutors {
     33 
     34   /**
     35    * A single instance of the {@link AsyncTaskExecutorFactory}, to which we delegate if it is
     36    * non-null, for injecting when testing.
     37    */
     38   private static AsyncTaskExecutorFactory mInjectedAsyncTaskExecutorFactory = null;
     39 
     40   /**
     41    * Creates an AsyncTaskExecutor that submits tasks to run with {@link AsyncTask#SERIAL_EXECUTOR}.
     42    */
     43   public static AsyncTaskExecutor createAsyncTaskExecutor() {
     44     synchronized (AsyncTaskExecutors.class) {
     45       if (mInjectedAsyncTaskExecutorFactory != null) {
     46         return mInjectedAsyncTaskExecutorFactory.createAsyncTaskExeuctor();
     47       }
     48       return new SimpleAsyncTaskExecutor(AsyncTask.SERIAL_EXECUTOR);
     49     }
     50   }
     51 
     52   /**
     53    * Creates an AsyncTaskExecutor that submits tasks to run with {@link
     54    * AsyncTask#THREAD_POOL_EXECUTOR}.
     55    */
     56   public static AsyncTaskExecutor createThreadPoolExecutor() {
     57     synchronized (AsyncTaskExecutors.class) {
     58       if (mInjectedAsyncTaskExecutorFactory != null) {
     59         return mInjectedAsyncTaskExecutorFactory.createAsyncTaskExeuctor();
     60       }
     61       return new SimpleAsyncTaskExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     62     }
     63   }
     64 
     65   public static void setFactoryForTest(AsyncTaskExecutorFactory factory) {
     66     synchronized (AsyncTaskExecutors.class) {
     67       mInjectedAsyncTaskExecutorFactory = factory;
     68     }
     69   }
     70 
     71   /** Interface for creating AsyncTaskExecutor objects. */
     72   public interface AsyncTaskExecutorFactory {
     73 
     74     AsyncTaskExecutor createAsyncTaskExeuctor();
     75   }
     76 
     77   static class SimpleAsyncTaskExecutor implements AsyncTaskExecutor {
     78 
     79     private final Executor mExecutor;
     80 
     81     public SimpleAsyncTaskExecutor(Executor executor) {
     82       mExecutor = executor;
     83     }
     84 
     85     @Override
     86     @MainThread
     87     public <T> AsyncTask<T, ?, ?> submit(Object identifer, AsyncTask<T, ?, ?> task, T... params) {
     88       Assert.isMainThread();
     89       return task.executeOnExecutor(mExecutor, params);
     90     }
     91   }
     92 }
     93