int main(int, char**) {
　　 //忽略了SIGPIPE信号，因为在SurfaceFlinger的Client-Server模型中，或者说IPC机制中，很可能会触发SIGPIPE信号，而这个信号的默认动作是终止进程
　　////当客户端/服务端的socket关闭时,防止进程退出
    signal(SIGPIPE, SIG_IGN);
    // When SF is launched in its own process, limit the number of
    // binder threads to 4.即SF进程开启后，线程池限制最大数量为4
    ProcessState::self()->setThreadPoolMaxThreadCount(4);
 
    // start the thread pool即启动线程池
　　//大多数程序都是需要IPC的，这里也需要，但是使用Binder机制是很繁琐的，所以Android为程序进程使用Binder机制封装了两个实现类：ProcessState、IPCThreadState
　　//其中ProcessState负责打开Binder驱动，进行mmap等准备工作；IPCThreadState负责具体线程跟Binder驱动进行命令交互。

    sp<processstate> ps(ProcessState::self());
    ps->startThreadPool();
 
    // instantiate surfaceflinger即实例化，以及设置进程优先级、事物处理策略
    sp<surfaceflinger> flinger = new SurfaceFlinger();
 
    setpriority(PRIO_PROCESS, 0, PRIORITY_URGENT_DISPLAY);
 
    set_sched_policy(0, SP_FOREGROUND);
 
#ifdef ENABLE_CPUSETS
    // Put most SurfaceFlinger threads in the system-background cpuset
    // Keeps us from unnecessarily using big cores
    // Do this after the binder thread pool init
    set_cpuset_policy(0, SP_SYSTEM);
#endif
 
    // initialize before clients can connect即初始化
    flinger->init();
 
    // publish surface flinger即发布SF，注册到ServiceManager，sp是strongponiter强指针（sp对象的析构函数调用RefBase的decStrong来减少强弱引用指针计数）
    sp<iservicemanager> sm(defaultServiceManager());
    sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false);
 
    // publish GpuService即注册GPUservice
    sp<gpuservice> gpuservice = new GpuService();
    sm->addService(String16(GpuService::SERVICE_NAME), gpuservice, false);
 
    struct sched_param param = {0};
    param.sched_priority = 2;
    if (sched_setscheduler(0, SCHED_FIFO, ¶m) != 0) {
        ALOGE("Couldn't set SCHED_FIFO");
    }
 
    // run surface flinger in this thread即运行当前线程
    flinger->run();
 
    return 0;
}