#include <userver/engine/condition_variable.hpp>

Detailed Description

std::condition_variable replacement for asynchronous tasks

Example usage:

    engine::Mutex mutex;
    engine::ConditionVariable cv;
    bool ok = false;
 
    auto task = engine::AsyncNoSpan([&] {
        std::unique_lock<engine::Mutex> lock(mutex);
        EXPECT_TRUE(cv.Wait(lock, [&ok] { return ok; }));
    });
 
    engine::Yield();
    EXPECT_FALSE(task.IsFinished());
 
    ok = true;
    cv.NotifyAll();
    engine::Yield();
    EXPECT_TRUE(task.IsFinished());

See also: Synchronization Primitives

Definition at line 27 of file condition_variable.hpp.

Public Member Functions
	ConditionVariable (const ConditionVariable &)=delete

	ConditionVariable (ConditionVariable &&)=delete

ConditionVariable &	operator= (const ConditionVariable &)=delete

ConditionVariable &	operator= (ConditionVariable &&)=delete

CvStatus	Wait (std::unique_lock< Mutex > &lock)

template<typename Predicate>
bool	Wait (std::unique_lock< Mutex > &lock, Predicate &&predicate)
	Suspends execution until the predicate is `true` when notification is received or the task is cancelled.

template<typename Rep, typename Period>
CvStatus	WaitFor (std::unique_lock< Mutex > &lock, std::chrono::duration< Rep, Period > timeout)
	Suspends execution until notified or until the timeout expires or until the task is cancelled.

template<typename Rep, typename Period, typename Predicate>
bool	WaitFor (std::unique_lock< Mutex > &lock, std::chrono::duration< Rep, Period > timeout, Predicate &&predicate)
	Suspends execution until the predicate is `true` when notified or the timeout expires or the task is cancelled.

template<typename Clock, typename Duration>
CvStatus	WaitUntil (std::unique_lock< Mutex > &lock, std::chrono::time_point< Clock, Duration > until)
	Suspends execution until notified or the time point is reached or the task is cancelled.

CvStatus	WaitUntil (std::unique_lock< Mutex > &lock, Deadline deadline)
	Suspends execution until notified or the deadline is reached or the task is cancelled.

template<typename Clock, typename Duration, typename Predicate>
bool	WaitUntil (std::unique_lock< Mutex > &lock, std::chrono::time_point< Clock, Duration > until, Predicate &&predicate)
	Suspends execution until the predicate is `true` when notified or the time point is reached or the task is cancelled.

template<typename Predicate>
bool	WaitUntil (std::unique_lock< Mutex > &lock, Deadline deadline, Predicate &&predicate)
	Suspends execution until the predicate is `true` when notified or the deadline is reached or the task is cancelled.

void	NotifyOne ()
	Notifies one of the waiting tasks.

void	NotifyAll ()
	Notifies all waiting tasks.

Member Function Documentation

◆ Wait() [1/2]

CvStatus engine::ConditionVariable::Wait ( std::unique_lock< Mutex > & lock )

nodiscard

Suspends execution until notified or cancelled

Returns: CvStatus::kNoTimeout if variable was notified; CvStatus::kCancelled if current task is being cancelled

◆ Wait() [2/2]

template<typename Predicate>

bool engine::ConditionVariable::Wait	(	std::unique_lock< Mutex > &	lock,
		Predicate &&	predicate )

nodiscard

Suspends execution until the predicate is true when notification is received or the task is cancelled.

Returns: the value of the predicate

Definition at line 101 of file condition_variable.hpp.

◆ WaitFor() [1/2]

template<typename Rep, typename Period>

CvStatus engine::ConditionVariable::WaitFor	(	std::unique_lock< Mutex > &	lock,
		std::chrono::duration< Rep, Period >	timeout )

Suspends execution until notified or until the timeout expires or until the task is cancelled.

Returns: CvStatus::kNoTimeout if variable was notified; CvStatus::kTimeout if timeout has expired; CvStatus::kCancelled if current task is being cancelled

Definition at line 106 of file condition_variable.hpp.

◆ WaitFor() [2/2]

template<typename Rep, typename Period, typename Predicate>

bool engine::ConditionVariable::WaitFor	(	std::unique_lock< Mutex > &	lock,
		std::chrono::duration< Rep, Period >	timeout,
		Predicate &&	predicate )

Suspends execution until the predicate is true when notified or the timeout expires or the task is cancelled.

Returns: the value of the predicate

Definition at line 111 of file condition_variable.hpp.

◆ WaitUntil() [1/4]

CvStatus engine::ConditionVariable::WaitUntil	(	std::unique_lock< Mutex > &	lock,
		Deadline	deadline )

Suspends execution until notified or the deadline is reached or the task is cancelled.

Returns: CvStatus::kNoTimeout if variable was notified; CvStatus::kTimeout if deadline was reached; CvStatus::kCancelled if current task is being cancelled

◆ WaitUntil() [2/4]

template<typename Predicate>

bool engine::ConditionVariable::WaitUntil	(	std::unique_lock< Mutex > &	lock,
		Deadline	deadline,
		Predicate &&	predicate )

Suspends execution until the predicate is true when notified or the deadline is reached or the task is cancelled.

Returns: the value of the predicate

Definition at line 134 of file condition_variable.hpp.

◆ WaitUntil() [3/4]

template<typename Clock, typename Duration>

CvStatus engine::ConditionVariable::WaitUntil	(	std::unique_lock< Mutex > &	lock,
		std::chrono::time_point< Clock, Duration >	until )

Suspends execution until notified or the time point is reached or the task is cancelled.

Returns: CvStatus::kNoTimeout if variable was notified; CvStatus::kTimeout if until time point was reached; CvStatus::kCancelled if current task is being cancelled

Definition at line 120 of file condition_variable.hpp.

◆ WaitUntil() [4/4]

template<typename Clock, typename Duration, typename Predicate>

bool engine::ConditionVariable::WaitUntil	(	std::unique_lock< Mutex > &	lock,
		std::chrono::time_point< Clock, Duration >	until,
		Predicate &&	predicate )

Suspends execution until the predicate is true when notified or the time point is reached or the task is cancelled.

Returns: the value of the predicate

Definition at line 125 of file condition_variable.hpp.

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

userver/engine/condition_variable.hpp