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 core
service 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& 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 vsyncSrc = new DispSyncSource(&mPrimaryDispSync,
vsyncPhaseOffsetNs, true, "app");
mEventThread = new EventThread(vsyncSrc);
sp 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(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// 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 token = mBuiltinDisplays[i];
sp producer;
sp consumer;
BufferQueue::createBufferQueue(&producer, &consumer,
new GraphicBufferAlloc());
sp fbs = new FramebufferSurface(*mHwc, i,
consumer);
int32_t hwcId = allocateHwcDisplayId(type);
sp 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。。。