std::condition_variable_any::wait

 

C++

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Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Discussione libreria di supporto

Threads Original: Threads The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
thread (C++11)
this_thread spazio dei nomi Original: this_thread namespace The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
get_id (C++11) yield (C++11)	sleep_for (C++11) sleep_until (C++11)
Mutua esclusione Original: Mutual exclusion The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
mutex (C++11) timed_mutex (C++11)	recursive_mutex (C++11) recursive_timed_mutex (C++11)
Blocco di gestione generico Original: Generic lock management The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lock_guard (C++11) unique_lock (C++11) defer_lock_t try_to_lock_t adopt_lock_t (C++11) (C++11) (C++11)	lock (C++11) try_lock (C++11) defer_lock try_to_lock adopt_lock (C++11) (C++11) (C++11)
Condizioni variabili Original: Condition variables The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
condition_variable (C++11)
condition_variable_any (C++11)
notify_all_at_thread_exit (C++11)
cv_status (C++11)
Futures Original: Futures The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
promise (C++11) future (C++11) shared_future (C++11) packaged_task (C++11) async (C++11)	launch (C++11) future_status (C++11) future_error (C++11) future_category (C++11) future_errc (C++11)

 

std::condition_variable_any

Membri funzioni Original: Member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

condition_variable_any::condition_variable_any

condition_variable_any::~condition_variable_any

Notifica Original: Notification The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

condition_variable_any::notify_one

condition_variable_any::notify_all

In attesa Original: Waiting The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

condition_variable_any::wait

condition_variable_any::wait_for

condition_variable_any::wait_until

 

template<class Lock > void wait( Lock& lock );	(1)	(dal C++11)
template<class Lock, class Predicate > void wait( Lock& lock, Predicate pred );	(2)	(dal C++11)

wait causa il blocco del thread corrente finchè la condiction variable non riceve una notifica (notify_one/notify_all) o si verifichi un risveglio spurio, opzionalmente il ciclo continua fino a che il predicato non è soddisfatto.

Original:

wait causes the current thread to block until the condition variable is notified or a spurious wakeup occurs, optionally looping until some predicate is satisfied.

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1)

Rilascia atomico lock, blocca il thread corrente di esecuzione, e lo aggiunge alla lista di thread in attesa su *this. Il filo sarà sbloccato quando notify_all() o notify_one() viene eseguito. Essa può anche essere sbloccato spurio. Quando sbloccato, indipendentemente dal motivo, lock è riacquisito ed esce wait. Se questa funzione termina via eccezionale, lock anche riacquistata.

Original:

Atomically releases lock, blocks the current executing thread, and adds it to the list of threads waiting on *this. The thread will be unblocked when notify_all() or notify_one() is executed. It may also be unblocked spuriously. When unblocked, regardless of the reason, lock is reacquired and wait exits. If this function exits via exception, lock is also reacquired.

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2)

Equivalente a

Original:

Equivalent to

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while(!pred()){
  wait(lock);
}

Questo overload può essere utilizzato per ignorare risvegli spuri in attesa di una condizione specifica per diventare vero.

Original:

This overload may be used to ignore spurious awakenings while waiting for a specific condition to become true.

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Parametri

lock	-	un oggetto di tipo Lock che soddisfi i requisiti BasicLockable, che devono essere bloccati dal thread corrente Original: an object of type Lock that meets the BasicLockable requirements, which must be locked by the current thread The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
pred	-	predicate which returns ​false se l'attesa deve essere continuato Original: if the waiting should be continued The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. . The signature of the predicate function should be equivalent to the following:  bool pred();​

Valore di ritorno

(Nessuno)

Original:

(none)

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Eccezioni

Può lanciare std::system_error, può anche propagare eccezioni generate dal lock.lock() o lock.unlock().

Original:

May throw std::system_error, may also propagate exceptions thrown by lock.lock() or lock.unlock().

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Note

Chiamare questa funzione se lock.mutex() non è bloccato dal thread corrente è un comportamento indefinito.

Original:

Calling this function if lock.mutex() is not locked by the current thread is undefined behavior.

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Chiamare questa funzione se lock.mutex() non è lo stesso mutex come quello utilizzato da tutti gli altri thread che sono attualmente in attesa sulla variabile stessa condizione è un comportamento indefinito.

Original:

Calling this function if lock.mutex() is not the same mutex as the one used by all other threads that are currently waiting on the same condition variable is undefined behavior.

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Esempio

#include <iostream>#include <condition_variable>#include <thread>#include <chrono>   std::condition_variable_any cv;std::mutex cv_m;int i =0;   void waits(){std::unique_lock<std::mutex> lk(cv_m);std::cerr<<"Waiting... \n"; cv.wait(lk, [](){return i ==1;});std::cerr<<"...finished waiting. i == 1\n";}   void signals(){std::this_thread::sleep_for(std::chrono::seconds(1));std::cerr<<"Notifying...\n"; cv.notify_all();std::this_thread::sleep_for(std::chrono::seconds(1)); i =1;std::cerr<<"Notifying again...\n"; cv.notify_all();}   int main(){std::thread t1(waits), t2(waits), t3(waits), t4(signals); t1.join(); t2.join(); t3.join(); t4.join();}

Output:

Waiting... Waiting... Waiting... Notifying... Notifying again... ...finished waiting. i == 1 ...finished waiting. i == 1 ...finished waiting. i == 1

Vedi anche

wait_for	Blocca il thread corrente fino a quando la variabile di condizione è svegliato o dopo la durata del timeout specificato Original: blocks the current thread until the condition variable is woken up or after the specified timeout duration The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)
wait_until	blocca il thread corrente fino a quando la variabile di condizione è svegliato o fino a che punto nel tempo specificato è stato raggiunto Original: blocks the current thread until the condition variable is woken up or until specified time point has been reached The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)