android surfaceflinger(1)-启动初始化1

  从本篇文章起，将对Android display系统框架进行分析，分析Android display必然涉及到surfaceflinger,故先分析一下，surfaceflinger的启动初始化流程。若文中有什么分析不对的，希望大家多多指出分享。谢谢！

1、surfaceflinger启动触发

  surfaceflinger是Android系统的一个重要后台本地服务，它是有init进程去启动的。

1.1 祖先进程init入口

system/core/init/init.cpp

int main(int argc, char** argv) {.......    init_parse_config_file("/init.rc");//解析init.rc文件    action_for_each_trigger("late-init",action_add_queue_tail);//启动服务    return 0;}

1.2 init.rc解析

在init.rc文件中，late-init->trigger boot-> class_start->surfaceflinger中的class core。依赖关系如下所示：

on late-init    trigger early-fs    trigger fs    trigger post-fs    trigger early-boot    trigger boot  on boot    class_start coreservice surfaceflinger /system/bin/surfaceflinger    class core    user system    group graphics drmrpc    onrestart restart zygote

在1.1节中，init_parse_config_file函数对init.rc解析完成后会将service类放在一个队列中，后面执行action_for_each_trigger（“late-init”,action_add_queue_tail）就会去启动对应的服务。

2、surfaceflinger进程启动

时序图如下：

  当init进程触发启动surfaceflinger服务时，系统就会fork一个surfaceflinger进程；进程入口为：
framwork/native/services/surfaceflinger/main_surfaceflinger.cpp

int main(int, char**) {    //限制binder 线程池最多可有4个线程    ProcessState::self()->setThreadPoolMaxThreadCount(4);    ALOGD("=zsx=  start surfaceflinger");    // start the thread pool    sp<ProcessState> ps(ProcessState::self());    ps->startThreadPool();    // 创建surfaceflinger实例    sp<SurfaceFlinger> flinger = new SurfaceFlinger();//见2.1节    // initialize before clients can connect    flinger->init();//见2.3节    // publish surface flinger    sp<IServiceManager> sm(defaultServiceManager());    sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false);//加入到ServiceManager服务管理器    // run in this thread    flinger->run();    return 0;}

2.1 创建surfaceflinger实例

new surfaceflinger时会去调用构造函数，第一次创建时还会执行onFirstRef();

SurfaceFlinger::SurfaceFlinger()    :   BnSurfaceComposer(),        mTransactionFlags(0),        mTransactionPending(false),        mAnimTransactionPending(false),        mLayersRemoved(false),        mRepaintEverything(0),        mRenderEngine(NULL),        mBootTime(systemTime()),        mVisibleRegionsDirty(false),        mHwWorkListDirty(false),        mAnimCompositionPending(false),        mDebugRegion(0),        mDebugDDMS(0),        mDebugDisableHWC(0),        mDebugDisableTransformHint(0),        mDebugInSwapBuffers(0),        mLastSwapBufferTime(0),        mDebugInTransaction(0),        mLastTransactionTime(0),        mBootFinished(false),        mForceFullDamage(false),        mPrimaryHWVsyncEnabled(false),        mHWVsyncAvailable(false),        mDaltonize(false),        mHasColorMatrix(false),        mHasPoweredOff(false),        mFrameBuckets(),        mTotalTime(0),        mLastSwapTime(0),        mDebugFps(0){    ALOGI("SurfaceFlinger is starting");    // debugging stuff...    char value[PROPERTY_VALUE_MAX];    property_get("ro.bq.gpu_to_cpu_unsupported", value, "0");    mGpuToCpuSupported = !atoi(value);    property_get("debug.sf.drop_missed_frames", value, "0");    mDropMissedFrames = atoi(value);    property_get("debug.sf.showupdates", value, "0");    mDebugRegion = atoi(value);    property_get("debug.sf.ddms", value, "0");    mDebugDDMS = atoi(value);    if (mDebugDDMS) {        if (!startDdmConnection()) {            // start failed, and DDMS debugging not enabled            mDebugDDMS = 0;        }    }    property_get("debug.sf.showfps", value, "0");    mDebugFps = atoi(value);    ALOGI_IF(mDebugRegion, "showupdates enabled");    ALOGI_IF(mDebugDDMS, "DDMS debugging enabled");    ALOGI_IF(mDebugFps,  "showfps enabled");}void SurfaceFlinger::onFirstRef(){    mEventQueue.init(this);//见2.2节}

2.2 消息队列初始化

void MessageQueue::init(const sp<SurfaceFlinger>& flinger){    mFlinger = flinger;    mLooper = new Looper(true);//实例化Looper    mHandler = new Handler(*this);//创建消息MessageQueue处理者Handler}

2.3 surfaceflinger类初始化

void SurfaceFlinger::init() {    Mutex::Autolock _l(mStateLock);    // initialize EGL for the default display    mEGLDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);    eglInitialize(mEGLDisplay, NULL, NULL);    // start the EventThread    sp<VSyncSource> vsyncSrc = new DispSyncSource(&mPrimaryDispSync,            vsyncPhaseOffsetNs, true, "app");    mEventThread = new EventThread(vsyncSrc);    sp<VSyncSource> sfVsyncSrc = new DispSyncSource(&mPrimaryDispSync,            sfVsyncPhaseOffsetNs, true, "sf");    mSFEventThread = new EventThread(sfVsyncSrc);    mEventQueue.setEventThread(mSFEventThread);    // 实例化硬件抽象层    mHwc = new HWComposer(this,            *static_cast<HWComposer::EventHandler *>(this));    // get a RenderEngine for the given display / config (can't fail)    mRenderEngine = RenderEngine::create(mEGLDisplay, mHwc->getVisualID());    // retrieve the EGL context that was selected/created    mEGLContext = mRenderEngine->getEGLContext();    LOG_ALWAYS_FATAL_IF(mEGLContext == EGL_NO_CONTEXT,            "couldn't create EGLContext");    // initialize our non-virtual displays    for (size_t i=0 ; i<DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES ; i++) {        DisplayDevice::DisplayType type((DisplayDevice::DisplayType)i);        // set-up the displays that are already connected        if (mHwc->isConnected(i) || type==DisplayDevice::DISPLAY_PRIMARY) {            // All non-virtual displays are currently considered secure.            bool isSecure = true;            createBuiltinDisplayLocked(type);            wp<IBinder> token = mBuiltinDisplays[i];            sp<IGraphicBufferProducer> producer;            sp<IGraphicBufferConsumer> consumer;            BufferQueue::createBufferQueue(&producer, &consumer,                    new GraphicBufferAlloc());            sp<FramebufferSurface> fbs = new FramebufferSurface(*mHwc, i,                    consumer);            int32_t hwcId = allocateHwcDisplayId(type);            sp<DisplayDevice> hw = new DisplayDevice(this,                    type, hwcId, mHwc->getFormat(hwcId), isSecure, token,                    fbs, producer,                    mRenderEngine->getEGLConfig());            if (i > DisplayDevice::DISPLAY_PRIMARY) {                hw->setPowerMode(HWC_POWER_MODE_NORMAL);            }            mDisplays.add(token, hw);        }    }    // make the GLContext current so that we can create textures when creating Layers    // (which may happens before we render something)    getDefaultDisplayDevice()->makeCurrent(mEGLDisplay, mEGLContext);    mEventControlThread = new EventControlThread(this);    mEventControlThread->run("EventControl", PRIORITY_URGENT_DISPLAY);    // set a fake vsync period if there is no HWComposer    if (mHwc->initCheck() != NO_ERROR) {        mPrimaryDispSync.setPeriod(16666667);    }    // initialize our drawing state    mDrawingState = mCurrentState;    // set initial conditions (e.g. unblank default device)    initializeDisplays();    // start boot animation    startBootAnim();}

SurfaceFlinger::init()里面做了很多初始化操作，后面将逐步分析。未完待续。。。