mAppConnectionHandle 和mSfConnectionHandle分析

最新推荐文章于 2025-08-13 21:05:35 发布

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何时创建 mAppConnectionHandle ？

在SurfaceFlinger的 initScheduler中：

 mAppConnectionHandle =
            mScheduler->createConnection("app", mFrameTimeline->getTokenManager(),
                                         /*workDuration=*/configs.late.appWorkDuration,
                                         /*readyDuration=*/configs.late.sfWorkDuration,
                                         impl::EventThread::InterceptVSyncsCallback());
    mSfConnectionHandle =
            mScheduler->createConnection("appSf", mFrameTimeline->getTokenManager(),
                                         /*workDuration=*/std::chrono::nanoseconds(vsyncPeriod),
                                         /*readyDuration=*/configs.late.sfWorkDuration,
                                         [this](nsecs_t timestamp) {
                                             mInterceptor->saveVSyncEvent(timestamp);
                                         });

上面创建了2个线程，一个是app线程，一个是appSf线程，
并且创建了这个EventThread对应的EventThreadConnection，此EventThreadConnection是一个 binder对象。

通过：

ConnectionHandle Scheduler::createConnection(std::unique_ptr<EventThread> eventThread) {
    const ConnectionHandle handle = ConnectionHandle{mNextConnectionHandleId++};
    ALOGV("Creating a connection handle with ID %" PRIuPTR, handle.id);

    auto connection = createConnectionInternal(eventThread.get());

    std::lock_guard<std::mutex> lock(mConnectionsLock);
    mConnections.emplace(handle, Connection{connection, std::move(eventThread)});
    return handle;
}

将这个handle 放入 mConnections 中，通过这个 handle就可以找到这个handle对应的eventThread。

客户端的DisplayEventReceiver使用以下代码：

DisplayEventReceiver::DisplayEventReceiver(
        ISurfaceComposer::VsyncSource vsyncSource,
        ISurfaceComposer::EventRegistrationFlags eventRegistration) {
    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
    if (sf != nullptr) {
        mEventConnection = sf->createDisplayEventConnection(vsyncSource, eventRegistration);
        if (mEventConnection != nullptr) {
            mDataChannel = std::make_unique<gui::BitTube>();
            const auto status = mEventConnection->stealReceiveChannel(mDataChannel.get());
            if (!status.isOk()) {
                ALOGE("stealReceiveChannel failed: %s", status.toString8().c_str());
                mInitError = std::make_optional<status_t>(status.transactionError());
                mDataChannel.reset();
                mEventConnection.clear();
            }
        }
    }
}

调用 sf的binder 方法 createDisplayEventConnection：

sp<IDisplayEventConnection> SurfaceFlinger::createDisplayEventConnection(
        ISurfaceComposer::VsyncSource vsyncSource,
        ISurfaceComposer::EventRegistrationFlags eventRegistration) {
    const auto& handle =
            vsyncSource == eVsyncSourceSurfaceFlinger ? mSfConnectionHandle : mAppConnectionHandle;

    return mScheduler->createDisplayEventConnection(handle, eventRegistration);
}

继续到：

sp<EventThreadConnection> Scheduler::createConnectionInternal(
        EventThread* eventThread, ISurfaceComposer::EventRegistrationFlags eventRegistration) {
    return eventThread->createEventConnection([&] { resync(); }, eventRegistration);
}

sp<IDisplayEventConnection> Scheduler::createDisplayEventConnection(
        ConnectionHandle handle, ISurfaceComposer::EventRegistrationFlags eventRegistration) {
    std::lock_guard<std::mutex> lock(mConnectionsLock);
    RETURN_IF_INVALID_HANDLE(handle, nullptr);getEventThreadConnectionCount
    return createConnectionInternal(mConnections[handle].thread.get(), eventRegistration);
}