content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.example.android.persistence.migrations;
  
  import android.os.Handler;
  import android.os.Looper;
  import androidx.annotation.NonNull;
  import java.util.concurrent.Executor;
  import java.util.concurrent.Executors;
  
  /**
   * Global executor pools for the whole application.
   * <p>
   * Grouping tasks like this avoids the effects of task starvation (e.g. disk reads don't wait behind
   * webservice requests).
   */
  public class AppExecutors {
  
      private static final int THREAD_COUNT = 3;
  
      private final Executor diskIO;
  
      private final Executor networkIO;
  
      private final Executor mainThread;
  
      AppExecutors(Executor diskIO, Executor networkIO, Executor mainThread) {
          this.diskIO = diskIO;
          this.networkIO = networkIO;
          this.mainThread = mainThread;
      }
  
      public AppExecutors() {
          this(Executors.newSingleThreadExecutor(), Executors.newFixedThreadPool(THREAD_COUNT),
                  new MainThreadExecutor());
      }
  
      public Executor diskIO() {
          return diskIO;
      }
  
      public Executor networkIO() {
          return networkIO;
      }
  
      public Executor mainThread() {
          return mainThread;
      }
  
      private static class MainThreadExecutor implements Executor {
          private final Handler mainThreadHandler = new Handler(Looper.getMainLooper());
  
          @Override
          public void execute(@NonNull Runnable command) {
              mainThreadHandler.post(command);
          }
      }
  }
  