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      1 /*
      2  * Copyright (C) 2016 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.server;
     18 
     19 import android.os.Build;
     20 import android.os.Process;
     21 import android.util.Slog;
     22 
     23 import com.android.internal.util.ConcurrentUtils;
     24 import com.android.internal.util.Preconditions;
     25 
     26 import java.util.List;
     27 import java.util.concurrent.Callable;
     28 import java.util.concurrent.ExecutorService;
     29 import java.util.concurrent.Future;
     30 import java.util.concurrent.TimeUnit;
     31 
     32 /**
     33  * Thread pool used during initialization of system server.
     34  * <p>System services can {@link #submit(Runnable)} tasks for execution during boot.
     35  * The pool will be shut down after {@link SystemService#PHASE_BOOT_COMPLETED}.
     36  * New tasks <em>should not</em> be submitted afterwards.
     37  *
     38  * @hide
     39  */
     40 public class SystemServerInitThreadPool {
     41     private static final String TAG = SystemServerInitThreadPool.class.getSimpleName();
     42     private static final int SHUTDOWN_TIMEOUT_MILLIS = 20000;
     43     private static final boolean IS_DEBUGGABLE = Build.IS_DEBUGGABLE;
     44 
     45     private static SystemServerInitThreadPool sInstance;
     46 
     47     private ExecutorService mService = ConcurrentUtils.newFixedThreadPool(4,
     48             "system-server-init-thread", Process.THREAD_PRIORITY_FOREGROUND);
     49 
     50     public static synchronized SystemServerInitThreadPool get() {
     51         if (sInstance == null) {
     52             sInstance = new SystemServerInitThreadPool();
     53         }
     54         Preconditions.checkState(sInstance.mService != null, "Cannot get " + TAG
     55                 + " - it has been shut down");
     56         return sInstance;
     57     }
     58 
     59     public Future<?> submit(Runnable runnable, String description) {
     60         if (IS_DEBUGGABLE) {
     61             return mService.submit(() -> {
     62                 Slog.d(TAG, "Started executing " + description);
     63                 try {
     64                     runnable.run();
     65                 } catch (RuntimeException e) {
     66                     Slog.e(TAG, "Failure in " + description + ": " + e, e);
     67                     throw e;
     68                 }
     69                 Slog.d(TAG, "Finished executing "  + description);
     70             });
     71         }
     72         return mService.submit(runnable);
     73     }
     74 
     75     static synchronized void shutdown() {
     76         if (sInstance != null && sInstance.mService != null) {
     77             sInstance.mService.shutdown();
     78             boolean terminated;
     79             try {
     80                 terminated = sInstance.mService.awaitTermination(SHUTDOWN_TIMEOUT_MILLIS,
     81                         TimeUnit.MILLISECONDS);
     82             } catch (InterruptedException e) {
     83                 Thread.currentThread().interrupt();
     84                 throw new IllegalStateException(TAG + " init interrupted");
     85             }
     86             List<Runnable> unstartedRunnables = sInstance.mService.shutdownNow();
     87             if (!terminated) {
     88                 throw new IllegalStateException("Cannot shutdown. Unstarted tasks "
     89                         + unstartedRunnables);
     90             }
     91             sInstance.mService = null; // Make mService eligible for GC
     92             Slog.d(TAG, "Shutdown successful");
     93         }
     94     }
     95 
     96 }
     97