Standard library header <shared_mutex>

 

C++

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Concepts library (C++20)

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Technical Specifications

 

Standard Library headers

Language Support
<cstddef> <limits> <climits> <contract>	<cfloat> <cstdint> <new> <coroutine>	<typeinfo> <exception> <initializer_list> <version>	<csignal> <csetjmp> <cstdarg>
Concepts
<concepts>
Diagnostics
<stdexcept>	<cassert>	<cerrno>	<system_error>
General utilities
<utility> <memory> <memory_resource> <scoped_allocator>     <compare>	<bitset> <tuple> <optional> <any> <variant>	<type_traits> <ratio> <chrono> <typeindex> <functional>	<ctime> <cstdlib>
Strings
<string> <string_view>	<cctype> <cwctype>	<cwchar> <cuchar>	<cstring> <charconv>
Localization
<locale>	<codecvt>	<clocale>
Containers
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
Iterators
<iterator>
Ranges
<ranges>
Algorithms
<algorithm>	<execution>
Numerics
<complex> <random>	<valarray> <numeric>	<cfenv> <cmath>	<bit>
Input/Output
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
Regular expressions
<regex>
Filesystem support
<filesystem>
Thread support
<thread> <atomic>	<mutex> <shared_mutex>	<condition_variable> <future>
C compatibility
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

 

This header is part of the thread support library.

Classes
shared_mutex (C++17)	provides shared mutual exclusion facility (class)
shared_timed_mutex (C++14)	provides shared mutual exclusion facility and implements locking with a timeout (class)
shared_lock (C++14)	implements movable shared mutex ownership wrapper (class template)
Functions
std::swap(std::shared_lock)	specialization of std::swap for shared_lock (function template)

Synopsis

namespace std {
    class shared_mutex;
    class shared_timed_mutex;
 
    template <class Mutex> class shared_lock;
 
    template <class Mutex>
    void swap(shared_lock<Mutex>& x, shared_lock<Mutex>& y) noexcept;
}

Class std::shared_mutex

class shared_mutex {
 public:
    typedef /*implementation-defined*/ native_handle_type;
 
    shared_mutex();
    ~shared_mutex();
    shared_mutex(const shared_mutex&) = delete;
    shared_mutex& operator=(const shared_mutex&) = delete;
 
    // Exclusive ownership
    void lock(); // blocking
    bool try_lock();
    void unlock();
 
    // Shared ownership
    void lock_shared(); // blocking
    bool try_lock_shared();
    void unlock_shared();
 
    // Getters
    native_handle_type native_handle();
};

Class std::shared_timed_mutex

class shared_timed_mutex {
 public:
    shared_timed_mutex();
    ~shared_timed_mutex();
    shared_timed_mutex(const shared_timed_mutex&) = delete;
    shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
 
    // Exclusive ownership
    void lock(); // blocking
    bool try_lock();
    template <class Rep, class Period>
    bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
    template <class Clock, class Duration>
    bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
    void unlock();
 
    // Shared ownership
    void lock_shared(); // blocking
    bool try_lock_shared();
    template <class Rep, class Period>
    bool try_lock_shared_for(const chrono::duration<Rep, Period>& rel_time);
    template <class Clock, class Duration>
    bool try_lock_shared_until(const chrono::time_point<Clock, Duration>& abs_time);
    void unlock_shared();
};

Class std::shared_lock

template <class Mutex>
class shared_lock {
 public:
    typedef Mutex mutex_type;
 
    shared_lock() noexcept;
    explicit shared_lock(mutex_type& m); // blocking
    shared_lock(mutex_type& m, defer_lock_t) noexcept;
    shared_lock(mutex_type& m, try_to_lock_t);
    shared_lock(mutex_type& m, adopt_lock_t);
    template <class Clock, class Duration>
    shared_lock(mutex_type& m,
    const chrono::time_point<Clock, Duration>& abs_time);
    template <class Rep, class Period>
    shared_lock(mutex_type& m,
    const chrono::duration<Rep, Period>& rel_time);
    ~shared_lock();
    shared_lock(shared_lock const&) = delete;
    shared_lock& operator=(shared_lock const&) = delete;
    shared_lock(shared_lock&& u) noexcept;
    shared_lock& operator=(shared_lock&& u) noexcept;
 
    void lock(); // blocking
    bool try_lock();
    template <class Rep, class Period>
    bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
    template <class Clock, class Duration>
    bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
    void unlock();
 
    // Setters
    void swap(shared_lock& u) noexcept;
    mutex_type* release() noexcept;
 
    // Getters
    bool owns_lock() const noexcept;
    explicit operator bool () const noexcept;
    mutex_type* mutex() const noexcept;
 
 private:
    mutex_type* pm; // exposition only
    bool owns; // exposition only
};