std::mutex::lock
De cppreference.com
<metanoindex/>
<tbody> </tbody> void lock(); |
(desde C++11) | |
Bloqueia o mutex. Se outro segmento já tenha travado o mutex, uma chamada para
lock irá bloquear a execução até que o bloqueio é adquirido.Original:
Locks the mutex. If another thread has already locked the mutex, a call to
lock will block execution until the lock is acquired.The text has been machine-translated via Google Translate.
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Parâmetros
(Nenhum)
Original:
(none)
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Valor de retorno
(Nenhum)
Original:
(none)
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Exceções
Lança std::system_error quando ocorrem erros, incluindo erros do sistema operacional subjacente que impediriam
lock de cumprir suas especificações.Original:
Throws std::system_error when errors occur, including errors from the underlying operating system that would prevent
lock from meeting its specifications.The text has been machine-translated via Google Translate.
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Note
A program may deadlock if a thread that already owns a mutex calls lock on that mutex. Alternatively, if an implementation can detect the deadlock, a resource_deadlock_would_occur error condition may be observed.
Exemplo
Este exemplo mostra como
lock unlock e pode ser utilizado para proteger os dados compartilhados .
Original:
This example shows how
lock and unlock can be used to protect shared data.
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#include <iostream>
#include <chrono>
#include <thread>
#include <mutex>
int g_num = 0; // protected by g_num_mutex
std::mutex g_num_mutex;
void slow_increment(int id)
{
for (int i = 0; i < 3; ++i) {
g_num_mutex.lock();
++g_num;
std::cout << id << " => " << g_num << '\n';
g_num_mutex.unlock();
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
int main()
{
std::thread t1(slow_increment, 0);
std::thread t2(slow_increment, 1);
t1.join();
t2.join();
}
Potencial saída:
0 => 1
1 => 2
0 => 3
1 => 4
0 => 5
1 => 6