std::condition_variable::notify_all

 

C++

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Technical Specifications

 

Thread support library

Threads
thread (C++11)
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Condition variables
condition_variable (C++11)
condition_variable_any (C++11)
notify_all_at_thread_exit (C++11)
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std::condition_variable

Member functions

condition_variable::condition_variable

condition_variable::~condition_variable

Notification

condition_variable::notify_one

condition_variable::notify_all

Waiting

condition_variable::wait

condition_variable::wait_for

condition_variable::wait_until

Native handle

condition_variable::native handle

 

void notify_all();		(since C++11)

Unblocks all threads currently waiting for *this.

Parameters

(none)

Return value

(none)

Exceptions

noexcept specification:  

noexcept

  

Notes

The effects of notify_one()/notify_all() and each of the three atomic parts of wait()/wait_for()/wait_until() (unlock+wait, wakeup, and lock) take place in a single total order that can be viewed as modification order of an atomic variable: the order is specific to this individual condition_variable. This makes it impossible for notify_one() to, for example, be delayed and unblock a thread that started waiting just after the call to notify_one() was made.

The notifying thread does not need to hold the lock on the same mutex as the one held by the waiting thread(s); in fact doing so is a pessimization, since the notified thread would immediately block again, waiting for the notifying thread to release the lock.