engine::ConditionVariable Class Reference

std::condition_variable replacement for asynchronous tasks More...

#include <userver/engine/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.

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.

Member Function Documentation

Wait() [1/2]

CvStatus engine::ConditionVariable::Wait

(

std::unique_lock< Mutex > &

lock

)

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
	)

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 107 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 113 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 119 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 142 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 127 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 134 of file condition_variable.hpp.

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

• userver/engine/condition_variable.hpp