|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Member functions | ||||
| Exclusive locking | ||||
| Shared locking | ||||
Defined in header <shared_mutex> | ||
class shared_timed_mutex; | (since C++14) | |
Theshared_timed_mutex class is a synchronization primitive that can be used to protect shared data from being simultaneously accessed by multiple threads. In contrast to other mutex types which facilitate exclusive access, ashared_timed_mutex has two levels of access:
Shared mutexes are usually used in situations when multiple readers can access the same resource at the same time without causing data races, but only one writer can do so.
In a manner similar totimed_mutex,shared_timed_mutex provides the ability to attempt to claim ownership of ashared_timed_mutex with a timeout via thetry_lock_for(),try_lock_until(),try_lock_shared_for(),try_lock_shared_until() member functions.
Theshared_timed_mutex class satisfies all requirements ofSharedTimedMutex andStandardLayoutType.
Contents |
| constructs the mutex (public member function)[edit] | |
| destroys the mutex (public member function)[edit] | |
operator= [deleted] | not copy-assignable (public member function)[edit] |
Exclusive locking | |
| locks the mutex, blocks if the mutex is not available (public member function)[edit] | |
| tries to lock the mutex, returns if the mutex is not available (public member function)[edit] | |
| tries to lock the mutex, returns if the mutex has been unavailable for the specified timeout duration (public member function)[edit] | |
| tries to lock the mutex, returns if the mutex has been unavailable until specified time point has been reached (public member function)[edit] | |
| unlocks the mutex (public member function)[edit] | |
Shared locking | |
| locks the mutex for shared ownership, blocks if the mutex is not available (public member function)[edit] | |
| tries to lock the mutex for shared ownership, returns if the mutex is not available (public member function)[edit] | |
| tries to lock the mutex for shared ownership, returns if the mutex has been unavailable for the specified timeout duration (public member function)[edit] | |
| tries to lock the mutex for shared ownership, returns if the mutex has been unavailable until specified time point has been reached (public member function)[edit] | |
| unlocks the mutex (shared ownership) (public member function)[edit] | |
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_shared_timed_mutex | 201402L | (C++14) | std::shared_timed_mutex |
| This section is incomplete Reason: build a motivating example |
A copy assignment operator for a class that holds resources that can handle multiple readers, but only one writer.
#include <mutex>#include <shared_mutex> class R{ mutable std::shared_timed_mutex mut;/* data */public: R& operator=(const R& other){// requires exclusive ownership to write to *thisstd::unique_lock<std::shared_timed_mutex> lhs(mut,std::defer_lock);// requires shared ownership to read from otherstd::shared_lock<std::shared_timed_mutex> rhs(other.mut,std::defer_lock);std::lock(lhs, rhs);/* assign data */return*this;}}; int main(){ R r;}
