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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 import com.android.server.am.ActivityManagerService;
     26 
     27 import java.util.ArrayList;
     28 import java.util.List;
     29 import java.util.concurrent.ExecutorService;
     30 import java.util.concurrent.Future;
     31 import java.util.concurrent.TimeUnit;
     32 
     33 /**
     34  * Thread pool used during initialization of system server.
     35  * <p>System services can {@link #submit(Runnable)} tasks for execution during boot.
     36  * The pool will be shut down after {@link SystemService#PHASE_BOOT_COMPLETED}.
     37  * New tasks <em>should not</em> be submitted afterwards.
     38  *
     39  * @hide
     40  */
     41 public class SystemServerInitThreadPool {
     42     private static final String TAG = SystemServerInitThreadPool.class.getSimpleName();
     43     private static final int SHUTDOWN_TIMEOUT_MILLIS = 20000;
     44     private static final boolean IS_DEBUGGABLE = Build.IS_DEBUGGABLE;
     45 
     46     private static SystemServerInitThreadPool sInstance;
     47 
     48     private ExecutorService mService = ConcurrentUtils.newFixedThreadPool(
     49             Runtime.getRuntime().availableProcessors(),
     50             "system-server-init-thread", Process.THREAD_PRIORITY_FOREGROUND);
     51 
     52     private List<String> mPendingTasks = new ArrayList<>();
     53 
     54     public static synchronized SystemServerInitThreadPool get() {
     55         if (sInstance == null) {
     56             sInstance = new SystemServerInitThreadPool();
     57         }
     58         Preconditions.checkState(sInstance.mService != null, "Cannot get " + TAG
     59                 + " - it has been shut down");
     60         return sInstance;
     61     }
     62 
     63     public Future<?> submit(Runnable runnable, String description) {
     64         synchronized (mPendingTasks) {
     65             mPendingTasks.add(description);
     66         }
     67         return mService.submit(() -> {
     68             if (IS_DEBUGGABLE) {
     69                 Slog.d(TAG, "Started executing " + description);
     70             }
     71             try {
     72                 runnable.run();
     73             } catch (RuntimeException e) {
     74                 Slog.e(TAG, "Failure in " + description + ": " + e, e);
     75                 throw e;
     76             }
     77             synchronized (mPendingTasks) {
     78                 mPendingTasks.remove(description);
     79             }
     80             if (IS_DEBUGGABLE) {
     81                 Slog.d(TAG, "Finished executing " + description);
     82             }
     83         });
     84     }
     85 
     86     static synchronized void shutdown() {
     87         if (sInstance != null && sInstance.mService != null) {
     88             sInstance.mService.shutdown();
     89             boolean terminated;
     90             try {
     91                 terminated = sInstance.mService.awaitTermination(SHUTDOWN_TIMEOUT_MILLIS,
     92                         TimeUnit.MILLISECONDS);
     93             } catch (InterruptedException e) {
     94                 Thread.currentThread().interrupt();
     95                 dumpStackTraces();
     96                 throw new IllegalStateException(TAG + " init interrupted");
     97             }
     98             if (!terminated) {
     99                 // dump stack must be called before shutdownNow() to collect stacktrace of threads
    100                 // in the thread pool.
    101                 dumpStackTraces();
    102             }
    103             List<Runnable> unstartedRunnables = sInstance.mService.shutdownNow();
    104             if (!terminated) {
    105                 final List<String> copy = new ArrayList<>();
    106                 synchronized (sInstance.mPendingTasks) {
    107                     copy.addAll(sInstance.mPendingTasks);
    108                 }
    109                 throw new IllegalStateException("Cannot shutdown. Unstarted tasks "
    110                         + unstartedRunnables + " Unfinished tasks " + copy);
    111             }
    112             sInstance.mService = null; // Make mService eligible for GC
    113             sInstance.mPendingTasks = null;
    114             Slog.d(TAG, "Shutdown successful");
    115         }
    116     }
    117 
    118     /**
    119      * A helper function to call ActivityManagerService.dumpStackTraces().
    120      */
    121     private static void dumpStackTraces() {
    122         final ArrayList<Integer> pids = new ArrayList<>();
    123         pids.add(Process.myPid());
    124         ActivityManagerService.dumpStackTraces(pids, null, null,
    125                 Watchdog.getInterestingNativePids());
    126     }
    127 }
    128