std::lock

 

C++

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Algoritmi

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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)

 

Defined in header <mutex>
template< class Lockable1, class Lockable2, class LockableN... > void lock( Lockable1& lock1, Lockable2& lock2, LockableN& lockn... );		(dal C++11)

Blocca la data Lockable oggetti lock1, lock2, ..., lockn utilizzando un algoritmo di evitare deadlock per evitare situazione di stallo.

Original:

Locks the given Lockable objects lock1, lock2, ..., lockn using a deadlock avoidance algorithm to avoid deadlock.

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Gli oggetti sono bloccati da una serie non precisata di chiamate verso lock, try_lock, unlock. Se una chiamata a lock o unlock genera un'eccezione, unlock si chiama per tutti gli oggetti bloccati prima rethrowing.

Original:

The objects are locked by an unspecified series of calls to lock, try_lock, unlock. If a call to lock or unlock results in an exception, unlock is called for any locked objects before rethrowing.

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Parametri

lock1, lock2, ... , lockn

-

il Lockable oggetti da bloccare Original: the Lockable objects to lock The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valore di ritorno

(Nessuno)

Original:

(none)

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Esempio

Nell'esempio seguente viene utilizzato per bloccare std::lock coppie di mutex senza stallo .

Original:

The following example uses std::lock to lock pairs of mutexes without deadlock.

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#include <mutex>
#include <thread>
#include <iostream>
#include <vector>
#include <functional>
#include <chrono>
 
struct Employee {
    Employee(int id) : id(id) {}
    int id;
    std::vector<int> lunch_partners;
    std::mutex m;
};
 
void send_mail(Employee &e1, Employee &e2)
{
    // simulate a time-consuming messaging operation
    std::this_thread::sleep_for(std::chrono::seconds(1));
}
 
void assign_lunch_partner(Employee &e1, Employee &e2)
{
    // use std::lock to acquire two locks without worrying about 
    // other calls to assign_lunch_partner deadlocking us
    std::lock(e1.m, e2.m);
 
    e1.lunch_partners.push_back(e2.id);
    e2.lunch_partners.push_back(e1.id);
 
    e1.m.unlock();
    e2.m.unlock();
 
    send_mail(e1, e2);
    send_mail(e2, e1);
}
 
int main()
{
    Employee alice(0), bob(1), christina(2), dave(3);
 
    // assign in parallel threads because mailing users about lunch assignments
    // takes a long time
    std::vector<std::thread> threads;
    threads.emplace_back(assign_lunch_partner, std::ref(alice), std::ref(bob));
    threads.emplace_back(assign_lunch_partner, std::ref(christina), std::ref(bob));
    threads.emplace_back(assign_lunch_partner, std::ref(christina), std::ref(alice));
    threads.emplace_back(assign_lunch_partner, std::ref(dave), std::ref(bob));
 
    for (auto &thread : threads) thread.join();
}

Vedi anche

try_lock (C++11)	tentativi di ottenere la proprietà del mutex con ripetute chiamate a try_lock Original: attempts to obtain ownership of mutexes via repeated calls to try_lock The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)