std::scoped_lock
From cppreference.com
| Defined in header <mutex>
|
||
| template< class... MutexTypes > class scoped_lock; |
(since C++17) | |
The class scoped_lock is a mutex wrapper that provides a convenient RAII-style mechanism for owning one or more mutexes for the duration of a scoped block.
When a scoped_lock object is created, it attempts to take ownership of the mutexes it is given. When control leaves the scope in which the scoped_lock object was created, the scoped_lock is destructed and the mutexes are released, in reverse order. If several mutexes are given, deadlock avoidance algorithm is used as if by std::lock.
The scoped_lock class is non-copyable.
Template parameters
| MutexTypes | - | the types of the mutexes to lock. The types must meet the Lockable requirements unless sizeof...(MutexTypes)==1, in which case the only type must meet BasicLockable
|
Member types
| Member type | Definition |
mutex_type
|
Mutex |
Member functions
| constructs a scoped_lock, optionally locking the given mutexes (public member function) | |
| destructs the scoped_lock object, unlocks the underlying mutexes (public member function) | |
| operator= [deleted] |
not copy-assignable (public member function) |
Example
| This section is incomplete Reason: should show multiple mutexes |
Run this code
#include <thread> #include <mutex> #include <iostream> int g_i = 0; std::mutex g_i_mutex; // protects g_i void safe_increment() { std::scoped_lock lock{g_i_mutex}; ++g_i; std::cout << std::this_thread::get_id() << ": " << g_i << '\n'; // g_i_mutex is automatically released when lock // goes out of scope } int main() { std::cout << __func__ << ": " << g_i << '\n'; std::thread t1(safe_increment); std::thread t2(safe_increment); t1.join(); t2.join(); std::cout << __func__ << ": " << g_i << '\n'; }
Possible output:
main: 0 140641306900224: 1 140641298507520: 2 main: 2
See also
| (C++11) |
implements movable mutex ownership wrapper (class template) |
| (C++11) |
implements a strictly scope-based mutex ownership wrapper (class template) |