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      1 /*
      2  * Copyright (C) 2017 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.app.Fragment;
     20 import android.app.FragmentManager;
     21 import android.os.AsyncTask;
     22 import android.os.Bundle;
     23 import android.support.annotation.MainThread;
     24 import android.support.annotation.Nullable;
     25 import com.android.dialer.common.Assert;
     26 import com.android.dialer.common.LogUtil;
     27 import com.android.dialer.common.concurrent.AsyncTaskExecutors.SimpleAsyncTaskExecutor;
     28 import com.android.dialer.common.concurrent.DialerExecutor.FailureListener;
     29 import com.android.dialer.common.concurrent.DialerExecutor.SuccessListener;
     30 import com.android.dialer.common.concurrent.DialerExecutor.Worker;
     31 import java.util.concurrent.ExecutorService;
     32 
     33 /**
     34  * Do not use this class directly. Instead use {@link DialerExecutors}.
     35  *
     36  * @param  the type of the object sent to the task upon execution
     37  * @param  the type of the result of the background computation
     38  */
     39 public final class DialerUiTaskFragment<InputT, OutputT> extends Fragment {
     40 
     41   private String taskId;
     42   private Worker<InputT, OutputT> worker;
     43   private SuccessListener<OutputT> successListener;
     44   private FailureListener failureListener;
     45 
     46   private AsyncTaskExecutor serialExecutor = AsyncTaskExecutors.createAsyncTaskExecutor();
     47   private AsyncTaskExecutor parallelExecutor = AsyncTaskExecutors.createThreadPoolExecutor();
     48 
     49   /**
     50    * Creates a new {@link DialerUiTaskFragment} or gets an existing one in the event that a
     51    * configuration change occurred while the previous activity's task was still running. Must be
     52    * called from onCreate of your activity or fragment.
     53    *
     54    * @param taskId used for the headless fragment ID and task ID
     55    * @param worker a function executed on a worker thread which accepts an {@link InputT} and
     56    *     returns an {@link OutputT}. It should ideally not be an inner class of your
     57    *     activity/fragment (meaning it should not be a lambda, anonymous, or non-static) but it can
     58    *     be a static nested class. The static nested class should not contain any reference to UI,
     59    *     including any activity or fragment or activity context, though it may reference some
     60    *     threadsafe system objects such as the application context.
     61    * @param successListener a function executed on the main thread upon task success. There are no
     62    *     restraints on this as it is executed on the main thread, so lambdas, anonymous, or inner
     63    *     classes of your activity or fragment are all fine.
     64    * @param failureListener a function executed on the main thread upon task failure. The exception
     65    *     is already logged so this can often be a no-op. There are no restraints on this as it is
     66    *     executed on the main thread, so lambdas, anonymous, or inner classes of your activity or
     67    *     fragment are all fine.
     68    * @param  the type of the object sent to the task upon execution
     69    * @param  the type of the result of the background computation
     70    * @return a {@link DialerUiTaskFragment} which may be used to call the "execute*" methods
     71    */
     72   @MainThread
     73   static <InputT, OutputT> DialerUiTaskFragment<InputT, OutputT> create(
     74       FragmentManager fragmentManager,
     75       String taskId,
     76       Worker<InputT, OutputT> worker,
     77       SuccessListener<OutputT> successListener,
     78       FailureListener failureListener,
     79       @Nullable ExecutorService serialExecutorService,
     80       @Nullable ExecutorService parallelExecutorService) {
     81     Assert.isMainThread();
     82 
     83     DialerUiTaskFragment<InputT, OutputT> fragment =
     84         (DialerUiTaskFragment<InputT, OutputT>) fragmentManager.findFragmentByTag(taskId);
     85 
     86     if (fragment == null) {
     87       LogUtil.i("DialerUiTaskFragment.create", "creating new DialerUiTaskFragment");
     88       fragment = new DialerUiTaskFragment<>();
     89       fragmentManager.beginTransaction().add(fragment, taskId).commit();
     90     }
     91     fragment.taskId = taskId;
     92     fragment.worker = worker;
     93     fragment.successListener = successListener;
     94     fragment.failureListener = failureListener;
     95     if (serialExecutorService != null) {
     96       fragment.serialExecutor = new SimpleAsyncTaskExecutor(serialExecutorService);
     97     }
     98     if (parallelExecutorService != null) {
     99       fragment.parallelExecutor = new SimpleAsyncTaskExecutor(parallelExecutorService);
    100     }
    101     return fragment;
    102   }
    103 
    104   @Override
    105   public void onCreate(Bundle savedInstanceState) {
    106     super.onCreate(savedInstanceState);
    107     setRetainInstance(true);
    108   }
    109 
    110   @Override
    111   public void onDetach() {
    112     super.onDetach();
    113     LogUtil.enterBlock("DialerUiTaskFragment.onDetach");
    114     taskId = null;
    115     successListener = null;
    116     failureListener = null;
    117   }
    118 
    119   void executeSerial(InputT input) {
    120     serialExecutor.submit(taskId, new InternalTask(), input);
    121   }
    122 
    123   void executeParallel(InputT input) {
    124     parallelExecutor.submit(taskId, new InternalTask(), input);
    125   }
    126 
    127   void executeOnCustomExecutor(ExecutorService executor, InputT input) {
    128     new SimpleAsyncTaskExecutor(executor).submit(taskId, new InternalTask(), input);
    129   }
    130 
    131   private final class InternalTask extends AsyncTask<InputT, Void, InternalTaskResult<OutputT>> {
    132 
    133     @SafeVarargs
    134     @Override
    135     protected final InternalTaskResult<OutputT> doInBackground(InputT... params) {
    136       try {
    137         return new InternalTaskResult<>(null, worker.doInBackground(params[0]));
    138       } catch (Throwable throwable) {
    139         LogUtil.e("InternalTask.doInBackground", "task failed", throwable);
    140         return new InternalTaskResult<>(throwable, null);
    141       }
    142     }
    143 
    144     @Override
    145     protected void onPostExecute(InternalTaskResult<OutputT> result) {
    146       if (result.throwable != null) {
    147         if (failureListener == null) {
    148           LogUtil.i("InternalTask.onPostExecute", "task failed but UI is dead");
    149         } else {
    150           failureListener.onFailure(result.throwable);
    151         }
    152       } else if (successListener == null) {
    153         LogUtil.i("InternalTask.onPostExecute", "task succeeded but UI is dead");
    154       } else {
    155         successListener.onSuccess(result.result);
    156       }
    157     }
    158   }
    159 
    160   private static class InternalTaskResult<OutputT> {
    161 
    162     private final Throwable throwable;
    163     private final OutputT result;
    164 
    165     InternalTaskResult(Throwable throwable, OutputT result) {
    166       this.throwable = throwable;
    167       this.result = result;
    168     }
    169   }
    170 }
    171