condition_variable_any Class

Use the class condition_variable_any to wait for an event that has any mutex type.

Syntax

class condition_variable_any;

Members

Constructors

Functions

condition_variable_any

Constructs a condition_variable_any object.

condition_variable_any();

Remarks

If not enough memory is available, the constructor throws a system_error object that has a not_enough_memory error code. If the object cannot be constructed because some other resource is not available, the constructor throws a system_error object that has a resource_unavailable_try_again error code.

notify_all

Unblocks all threads that are waiting for the condition_variable_any object.

void notify_all() noexcept;

notify_one

Unblocks one of the threads that are waiting on the condition_variable_any object.

void notify_one() noexcept;

wait

Blocks a thread.

template <class Lock>
void wait(Lock& Lck);

template <class Lock, class Predicate>
void wait(Lock& Lck, Predicate Pred);

Parameters

Lck
A mutex object of any type.

Pred
Any expression that returns true or false.

Remarks

The first method blocks until the condition_variable_any object is signaled by a call to notify_one or notify_all. It can also wake up spuriously.

The second method in effect executes the following code.

while (!Pred())
    wait(Lck);

wait_for

Blocks a thread, and sets a time interval after which the thread unblocks.

template <class Lock, class Rep, class Period>
bool wait_for(Lock& Lck, const chrono::duration<Rep, Period>& Rel_time);

template <class Lock, class Rep, class Period, class Predicate>
bool wait_for(Lock& Lck, const chrono::duration<Rep, Period>& Rel_time, Predicate Pred);

Parameters

Lck
A mutex object of any type.

Rel_time
A chrono::duration object that specifies the amount of time before the thread wakes up.

Pred
Any expression that returns true or false.

Return Value

The first method returns cv_status::timeout if the wait terminates when Rel_time has elapsed. Otherwise, the method returns cv_status::no_timeout.

The second method returns the value of Pred.

Remarks

The first method blocks until the condition_variable_any object is signaled by a call to notify_one or notify_all, or until the time interval Rel_time has elapsed. It can also wake up spuriously.

The second method in effect executes the following code.

while(!Pred())
    if(wait_for(Lck, Rel_time) == cv_status::timeout)
    return Pred();

return true;

wait_until

Blocks a thread, and sets a maximum point in time at which the thread unblocks.

template <class Lock, class Clock, class Duration>
void wait_until(Lock& Lck, const chrono::time_point<Clock, Duration>& Abs_time);

template <class Lock, class Clock, class Duration, class Predicate>
void wait_until(
    Lock& Lck,
    const chrono::time_point<Clock, Duration>& Abs_time,
    Predicate Pred);

template <class Lock>
void wait_until(Lock Lck, const xtime* Abs_time);

template <class Lock, class Predicate>
void wait_until(
    Lock Lck,
    const xtime* Abs_time,
    Predicate Pred);

Parameters

Lck
A mutex object.

Abs_time
A chrono::time_point object.

Pred
Any expression that returns true or false.

Return Value

Methods that return a cv_status type return cv_status::timeout if the wait terminates when Abs_time elapses. Otherwise, the methods return cv_status::no_timeout.

Methods that return a bool return the value of Pred.

Remarks

The first method blocks until the condition_variable object is signaled by a call to notify_one or notify_all, or until Abs_time. It can also wake up spuriously.

The second method in effect executes the following code.

while(!Pred())
    if(wait_until(Lck, Abs_time) == cv_status::timeout)
    return Pred();

return true;

The third and fourth methods use a pointer to an object of type xtime to replace the chrono::time_point object. The xtime object specifies the maximum amount of time to wait for a signal.