Cubietruck---20.SurfaceFlinger创建过程分析

一.surfaceFlinger的启动过程
1. 阻止system_init启动SF
在init.rc中

1. # Set this property so surfaceflinger is not started by system_init
   
2.     setprop system_init.startsurfaceflinger 0

即然上面说了要阻止system_init把surfaceFlinger启动,那就看一下是如何阻止的吧.
在frameworks/base/cmds/system_server/library/system_init.cpp中

1. extern "C" status_t system_init()
   
2. {
3.     char propBuf[PROPERTY_VALUE_MAX];
   
4.     property_get("system_init.startsurfaceflinger", propBuf, "1");
   
5.     if (strcmp(propBuf, "1") == 0) {
   
6.         SurfaceFlinger::instantiate();
   
7.     } 
   
8. }
   

获取system_init.startsurfaceflinger这个属性的值,如果为1的话,就启动sf.
但是在init.rc中把这个属性值设为了0,这个就不会启动sf了.
2. SF的真正启动过程
还是在init.rc中

1. service surfaceflinger /system/bin/surfaceflinger
   
2.     class main
   
3.     user system
   
4.     group graphics
   
5.     onrestart restart zygote

在frameworks/native/cmds/surfaceflinger/main_surfaceflinger.cpp中

1. int main(int argc, char** argv) {
   
2.     SurfaceFlinger::publishAndJoinThreadPool(true);
   
3.     ProcessState::self()->setThreadPoolMaxThreadCount(4);
   
4.     return 0;
   
5. }

在frameworks/native/include/binder/BinderService.h中

1. static void publishAndJoinThreadPool(bool allowIsolated = false) {
   
2.     sp<IServiceManager> sm(defaultServiceManager());
   
3.     sm->addService(String16(SERVICE::getServiceName()), new SERVICE(), allowIsolated);
   
4.     ProcessState::self()->startThreadPool();
   
5.     IPCThreadState::self()->joinThreadPool();
   
6. }

其中的new SERVICE就是new一个surfaceflinger,进入surfaceflinger的构造函数
3. onFirstRef启动主线程
因为SurfaceFlinger继承自class Thread, Thread又继承自RefBase
在 frameworks/native/include/utils/Thread.h中, class Thread : virtual public RefBase

1. void SurfaceFlinger::onFirstRef()
   
2. {
   
3.     mEventQueue.init(this);              //消息队列初始化
   
4.     run("SurfaceFlinger", PRIORITY_URGENT_DISPLAY);  //启动工作线程
   
5.     mReadyToRunBarrier.wait();   //等侍标志
   
6. }

1. status_t SurfaceFlinger::readyToRun()
   
2. {
   
3.     mEGLDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
   
4.     eglInitialize(mEGLDisplay, NULL, NULL);
5. 
   
6.     mHwc = new HWComposer(this, *static_cast<HWComposer::EventHandler *>(this));
   
7. 
   
8.     EGLint format = mHwc->getVisualID();
   
9.     mEGLConfig = selectEGLConfig(mEGLDisplay, format);
   
10.     mEGLContext = createGLContext(mEGLDisplay, mEGLConfig);
    
11. 
    
12. 
    
13.     for (size_t i=0 ; i<DisplayDevice::NUM_DISPLAY_TYPES ; i++) {
    
14.         DisplayDevice::DisplayType type((DisplayDevice::DisplayType)i);
    
15.         mDefaultDisplays[i] = new BBinder();
    
16.         wp<IBinder> token = mDefaultDisplays[i];
17. 
    
18.         if (mHwc->isConnected(i) || type==DisplayDevice::DISPLAY_PRIMARY) {
19.             bool isSecure = true;
    
20.             mCurrentState.displays.add(token, DisplayDeviceState(type));
    
21.             sp<FramebufferSurface> fbs = new FramebufferSurface(*mHwc, i);
    
22.             sp<SurfaceTextureClient> stc = new SurfaceTextureClient(static_cast< sp<ISurfaceTexture> >(fbs->getBufferQueue()));
    
23.             sp<DisplayDevice> hw = new DisplayDevice(this, type, isSecure, token, stc, fbs, mEGLConfig);
    
24.             if (i > DisplayDevice::DISPLAY_PRIMARY)
    
25.                 hw->acquireScreen();            
    
26.             mDisplays.add(token, hw);
    
27.         }
    
28.     }
    
29.     sp<const DisplayDevice> hw(getDefaultDisplayDevice());
    
30. 
    
31.     DisplayDevice::makeCurrent(mEGLDisplay, hw, mEGLContext);
    
32.     initializeGL(mEGLDisplay);
    
33. 
    
34.     mEventThread = new EventThread(this);
    
35.     mEventQueue.setEventThread(mEventThread);
    
36. 
    
37.     mDrawingState = mCurrentState;
38. 
    
39.     mReadyToRunBarrier.open();
40. 
    
41.     initializeDisplays();
42. 
    
43.     startBootAnim();
    
44. 
    
45.     return NO_ERROR;
    
46. }

a. 初始化egl
b. 新建 HWComposer
c. 新建 DisplayDevice
    

1. DisplayDevice::DisplayDevice(const sp<SurfaceFlinger>& flinger, ...)
   
2. {
   
3.     init(config);
4.     mDisplayDispatcher = new DisplayDispatcher(mFlinger); //新建一个DisplayDispatcher
   
5. }