AndroidO Treble架构下hwservicemanager启动过程

hwservicemanager是hidl服务管理中心，负责管理系统中的所有hidl服务，由init进程启动。

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1. service hwservicemanager /system/bin/hwservicemanager  
2.     user system  
3.     disabled  
4.     group system readproc  
5.     critical  
6.     onrestart setprop hwservicemanager.ready false  
7.     onrestart class_restart hal  
8.     onrestart class_restart early_hal  
9.     writepid /dev/cpuset/system-background/tasks  
10.     class animation  
11.     shutdown critical  

service hwservicemanager /system/bin/hwservicemanager
    user system
    disabled
    group system readproc
    critical
    onrestart setprop hwservicemanager.ready false
    onrestart class_restart hal
    onrestart class_restart early_hal
    writepid /dev/cpuset/system-background/tasks
    class animation
    shutdown critical

hwservicemanager的源码位于：system/hwservicemanager

C:\Source\androido\system\hwservicemanager\service.cpp

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1. int main() {  
2.     configureRpcThreadpool(1, true /* callerWillJoin */);  
3.     //创建ServiceManager对象  
4.     ServiceManager *manager = new ServiceManager();  
5.     //将ServiceManager对象自身注册到mServiceMap表中  
6.     if (!manager->add(serviceName, manager)) {  
7.         ALOGE(”Failed to register hwservicemanager with itself.”);  
8.     }  
9.     //创建TokenManager对象  
10.     TokenManager *tokenManager = new TokenManager();  
11.     //将TokenManager对象自身注册到mServiceMap表中  
12.     if (!manager->add(serviceName, tokenManager)) {  
13.         ALOGE(”Failed to register ITokenManager with hwservicemanager.”);  
14.     }  
15.     //建立消息循环  
16.     sp<Looper> looper(Looper::prepare(0 /* opts */));  
17.   
18.     int binder_fd = -1;  
19.     //将主线程加入binder线程池，并得到/dev/hwbinder句柄  
20.     IPCThreadState::self()->setupPolling(&binder_fd);  
21.     if (binder_fd < 0) {  
22.         ALOGE(”Failed to aquire binder FD. Aborting…”);  
23.         return -1;  
24.     }  
25.     // Flush after setupPolling(), to make sure the binder driver  
26.     // knows about this thread handling commands.  
27.     IPCThreadState::self()->flushCommands();  
28.     //主线程监听EVENT_INPUT，通过回调BinderCallback处理  
29.     sp<BinderCallback> cb(new BinderCallback);  
30.     if (looper->addFd(binder_fd, Looper::POLL_CALLBACK, Looper::EVENT_INPUT, cb,  
31.             nullptr) != 1) {  
32.         ALOGE(”Failed to add hwbinder FD to Looper. Aborting…”);  
33.         return -1;  
34.     }  
35.     //创建BnHwServiceManager对象  
36.     // Tell IPCThreadState we’re the service manager  
37.     sp<BnHwServiceManager> service = new BnHwServiceManager(manager);  
38.     IPCThreadState::self()->setTheContextObject(service);  
39.     // Then tell binder kernel  
40.     ioctl(binder_fd, BINDER_SET_CONTEXT_MGR, 0);  
41.     // Only enable FIFO inheritance for hwbinder  
42.     // FIXME: remove define when in the kernel  
43. #define BINDER_SET_INHERIT_FIFO_PRIO    _IO(‘b’, 10)  
44.   
45.     int rc = ioctl(binder_fd, BINDER_SET_INHERIT_FIFO_PRIO);  
46.     if (rc) {  
47.         ALOGE(”BINDER_SET_INHERIT_FIFO_PRIO failed with error %d\n”, rc);  
48.     }  
49.     //通过属性方式告知其他进程，hwservicemanager已经就绪  
50.     rc = property_set(”hwservicemanager.ready”, “true”);  
51.     if (rc) {  
52.         ALOGE(”Failed to set \”hwservicemanager.ready\” (error %d). ”\  
53.               ”HAL services will not start!\n”, rc);  
54.     }  
55.     //进入消息循环  
56.     while (true) {  
57.         looper->pollAll(-1 /* timeoutMillis */);  
58.     }  
59.   
60.     return 0;  
61. }  

int main() {
    configureRpcThreadpool(1, true /* callerWillJoin */);
    //创建ServiceManager对象
    ServiceManager *manager = new ServiceManager();
    //将ServiceManager对象自身注册到mServiceMap表中
    if (!manager->add(serviceName, manager)) {
        ALOGE("Failed to register hwservicemanager with itself.");
    }
    //创建TokenManager对象
    TokenManager *tokenManager = new TokenManager();
    //将TokenManager对象自身注册到mServiceMap表中
    if (!manager->add(serviceName, tokenManager)) {
        ALOGE("Failed to register ITokenManager with hwservicemanager.");
    }
    //建立消息循环
    sp<Looper> looper(Looper::prepare(0 /* opts */));

    int binder_fd = -1;
    //将主线程加入binder线程池，并得到/dev/hwbinder句柄
    IPCThreadState::self()->setupPolling(&binder_fd);
    if (binder_fd < 0) {
        ALOGE("Failed to aquire binder FD. Aborting...");
        return -1;
    }
    // Flush after setupPolling(), to make sure the binder driver
    // knows about this thread handling commands.
    IPCThreadState::self()->flushCommands();
    //主线程监听EVENT_INPUT，通过回调BinderCallback处理
    sp<BinderCallback> cb(new BinderCallback);
    if (looper->addFd(binder_fd, Looper::POLL_CALLBACK, Looper::EVENT_INPUT, cb,
            nullptr) != 1) {
        ALOGE("Failed to add hwbinder FD to Looper. Aborting...");
        return -1;
    }
    //创建BnHwServiceManager对象
    // Tell IPCThreadState we're the service manager
    sp<BnHwServiceManager> service = new BnHwServiceManager(manager);
    IPCThreadState::self()->setTheContextObject(service);
    // Then tell binder kernel
    ioctl(binder_fd, BINDER_SET_CONTEXT_MGR, 0);
    // Only enable FIFO inheritance for hwbinder
    // FIXME: remove define when in the kernel