@GuardedBy注解

参考：https://blog.csdn.net/lihenair/article/details/61913542

在ActivityThread中看到如下的用法：

    @GuardedBy("mResourcesManager")
    final ArrayMap<String, WeakReference<LoadedApk>> mPackages = new ArrayMap<>();
    @GuardedBy("mResourcesManager")
    final ArrayMap<String, WeakReference<LoadedApk>> mResourcePackages = new ArrayMap<>();
    @GuardedBy("mResourcesManager")
    final ArrayList<ActivityClientRecord> mRelaunchingActivities = new ArrayList<>();
    @GuardedBy("mResourcesManager")
    Configuration mPendingConfiguration = null;
    @GuardedBy("mResourcesManager")
    int mLifecycleSeq = 0;

    private final ResourcesManager mResourcesManager;

对这些成员变量加上了注解词@GuardedBy("mResourcesManager")。

根据参考的文章，这个是一个同步锁，只有在线程持有mResourcesManager对象锁时，才能使用这写变量。

如：

    private int getLifecycleSeq() {
        synchronized (mResourcesManager) {
            return mLifecycleSeq++;
        }
    }