cuttlefish::HostModeCtrl Class Reference

#include <host_mode_ctrl.h>

Public Types
enum class	ModeType : std::uint8_t { kAndroidMode = 55 , kConfUI_Mode = 77 }

Public Member Functions
	INJECT (HostModeCtrl())
void	WaitAndroidMode ()
void	SetMode (const ModeType mode)
auto	GetMode ()
auto	IsConfirmatioUiMode ()
auto	IsAndroidMode ()

Static Public Member Functions
static HostModeCtrl &	Get ()

Private Attributes
std::mutex	mode_mtx_
std::condition_variable	and_mode_cv_
std::condition_variable	confui_mode_cv_
std::atomic< ModeType >	atomic_mode_

Detailed Description

mechanism to orchestrate concurrent executions of threads that work for screen connector

Within WebRTC service, it tells when it is now in the Android Mode or Confirmation UI mode

Member Enumeration Documentation

ModeType

enum class cuttlefish::HostModeCtrl::ModeType : std::uint8_t

strong

Enumerator
kAndroidMode
kConfUI_Mode

Member Function Documentation

Get()

static HostModeCtrl & cuttlefish::HostModeCtrl::Get ( )

inlinestatic

GetMode()

auto cuttlefish::HostModeCtrl::GetMode ( )

inline

INJECT()

cuttlefish::HostModeCtrl::INJECT ( HostModeCtrl()  )

inline

IsAndroidMode()

auto cuttlefish::HostModeCtrl::IsAndroidMode ( )

inline

IsConfirmatioUiMode()

auto cuttlefish::HostModeCtrl::IsConfirmatioUiMode ( )

inline

SetMode()

void cuttlefish::HostModeCtrl::SetMode ( const ModeType  mode )

inline

WaitAndroidMode()

void cuttlefish::HostModeCtrl::WaitAndroidMode ( )

inline

The thread that enqueues Android frames will call this to wait until the mode is kAndroidMode

Logically, using atomic_mode_ alone is not sufficient. Using mutex alone is logically complete but slow.

Note that most of the time, the mode is kAndroidMode. Also, note that this method is called at every single frame.

As an optimization, we check atomic_mode_ first. If failed, we wait for kAndroidMode with mutex-based lock

The actual synchronization is not at the and_mode_cv_.wait line but at this line: if (atomic_mode_ == ModeType::kAndroidMode) {

This trick reduces the flag checking delays by 70+% on a Gentoo based amd64 desktop, with Linux 5.10

Member Data Documentation

and_mode_cv_

std::condition_variable cuttlefish::HostModeCtrl::and_mode_cv_

private

atomic_mode_

std::atomic<ModeType> cuttlefish::HostModeCtrl::atomic_mode_

private

confui_mode_cv_

std::condition_variable cuttlefish::HostModeCtrl::confui_mode_cv_

private

mode_mtx_

std::mutex cuttlefish::HostModeCtrl::mode_mtx_

private

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The documentation for this class was generated from the following file:

• cuttlefish/host/libs/confui/host_mode_ctrl.h