1. SurfaceFlinger程序入口
/frameworks/native/services/surfaceflinger/main_surfaceflinger.cpp
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| int main(int, char**) {
signal(SIGPIPE, SIG_IGN);
hardware::configureRpcThreadpool(1 /* maxThreads */,
false /* callerWillJoin */);
startGraphicsAllocatorService();
// When SF is launched in its own process, limit the number of
// binder threads to 4.
ProcessState::self()->setThreadPoolMaxThreadCount(4);
// Set uclamp.min setting on all threads, maybe an overkill but we want
// to cover important threads like RenderEngine.
if (SurfaceFlinger::setSchedAttr(true) != NO_ERROR) {
ALOGW("Couldn't set uclamp.min: %s\n", strerror(errno));
}
// The binder threadpool we start will inherit sched policy and priority
// of (this) creating thread. We want the binder thread pool to have
// SCHED_FIFO policy and priority 1 (lowest RT priority)
// Once the pool is created we reset this thread's priority back to
// original.
int newPriority = 0;
int origPolicy = sched_getscheduler(0);
struct sched_param origSchedParam;
int errorInPriorityModification = sched_getparam(0, &origSchedParam);
if (errorInPriorityModification == 0) {
int policy = SCHED_FIFO;
newPriority = sched_get_priority_min(policy);
struct sched_param param;
param.sched_priority = newPriority;
errorInPriorityModification = sched_setscheduler(0, policy, ¶m);
}
// start the thread pool
sp<ProcessState> ps(ProcessState::self());
ps->startThreadPool();
// Reset current thread's policy and priority
if (errorInPriorityModification == 0) {
errorInPriorityModification = sched_setscheduler(0, origPolicy, &origSchedParam);
} else {
ALOGE("Failed to set SurfaceFlinger binder threadpool priority to SCHED_FIFO");
}
// instantiate surfaceflinger
sp<SurfaceFlinger> flinger = surfaceflinger::createSurfaceFlinger();
// Set the minimum policy of surfaceflinger node to be SCHED_FIFO.
// So any thread with policy/priority lower than {SCHED_FIFO, 1}, will run
// at least with SCHED_FIFO policy and priority 1.
if (errorInPriorityModification == 0) {
flinger->setMinSchedulerPolicy(SCHED_FIFO, newPriority);
}
setpriority(PRIO_PROCESS, 0, PRIORITY_URGENT_DISPLAY);
set_sched_policy(0, SP_FOREGROUND);
// Put most SurfaceFlinger threads in the system-background cpuset
// Keeps us from unnecessarily using big cores
// Do this after the binder thread pool init
if (cpusets_enabled()) set_cpuset_policy(0, SP_SYSTEM);
// initialize before clients can connect
flinger->init();
// publish surface flinger
sp<IServiceManager> sm(defaultServiceManager());
sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false,
IServiceManager::DUMP_FLAG_PRIORITY_CRITICAL | IServiceManager::DUMP_FLAG_PROTO);
startDisplayService(); // dependency on SF getting registered above
if (SurfaceFlinger::setSchedFifo(true) != NO_ERROR) {
ALOGW("Couldn't set to SCHED_FIFO: %s", strerror(errno));
}
// run surface flinger in this thread
flinger->run();/ Use StartPropertySetThread instead.
}
void SurfaceFlinger::onFirstRef() {
// std::unique_ptr<MessageQueue> mEventQueue;
mEventQueue->init(this);
}
void MessageQueue::init(const sp<SurfaceFlinger>& flinger) {
mFlinger = flinger;
mLooper = new Looper(true);
mHandler = new Handler(*this);
} |
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main方法是surfaceflinger的入口。该方法中关注到sp<SurfaceFlinger> flinger = surfaceflinger::createSurfaceFlinger()。这里创建了surfaceFlinger,实际上这里的sp隐含了一个方法调用——onFirstRef()。这个方法有点特殊,在代码层面看不到调用关系。实际上它是当强指针(sp-strong point)第一次被引用时,会被调用。继续可以看到在onFirstRef中执行了mEventQueue的init方法。继续看这个init方法,实际上创建了Looer和handler两个成员。这连个成员的作用是循环接受和发送消息,处理消息的作用。
注意到flinger→init()方法。该方法中调用mCompositionEngine->setRenderEngine(renderengine::RenderEngine::create初始化了renderEngine。renderEngine是用来做软件合成的。
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| // Use StartPropertySetThread instead.
void SurfaceFlinger::init() {
ALOGI( "SurfaceFlinger's main thread ready to run. "
"Initializing graphics H/W...");
Mutex::Autolock _l(mStateLock);
// Get a RenderEngine for the given display / config (can't fail)
// TODO(b/77156734): We need to stop casting and use HAL types when possible.
// Sending maxFrameBufferAcquiredBuffers as the cache size is tightly tuned to single-display.
mCompositionEngine->setRenderEngine(renderengine::RenderEngine::create(
renderengine::RenderEngineCreationArgs::Builder()
.setPixelFormat(static_cast<int32_t>(defaultCompositionPixelFormat))
.setImageCacheSize(maxFrameBufferAcquiredBuffers)
.setUseColorManagerment(useColorManagement)
.setEnableProtectedContext(enable_protected_contents(false))
.setPrecacheToneMapperShaderOnly(false)
.setSupportsBackgroundBlur(mSupportsBlur)
.setContextPriority(
useContextPriority
? renderengine::RenderEngine::ContextPriority::REALTIME
: renderengine::RenderEngine::ContextPriority::MEDIUM)
.build())); |
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最后调用flinger->run()方法,进入消息等待中。