concurrent::Variable< Data, Mutex > Class Template Reference

#include <userver/concurrent/variable.hpp>

Detailed Description

template<typename Data, typename Mutex = engine::Mutex>
class concurrent::Variable< Data, Mutex >

Container for shared data protected with a mutex of any type (mutex, shared mutex, etc.).

Example usage:

    constexpr auto kTestString = "Test string";
 
    struct Data {
        int x = 0;
        std::string s{};
    };
    // If you do not specify the 2nd template parameter,
    // then by default Variable is protected by engine::Mutex.
    concurrent::Variable<Data, engine::SharedMutex> data;
 
    {
        // We get a smart pointer to the data,
        // the smart pointer stores std::lock_guard
        auto data_ptr = data.Lock();
        data_ptr->s = kTestString;
    }
 
    {
        // We get a smart pointer to the data,
        // the smart pointer stores std::shared_lock
        auto data_ptr = data.SharedLock();
        // we can read data, we cannot write
        ASSERT_EQ(data_ptr->s, kTestString);
    }

See also

Synchronization Primitives

Definition at line 58 of file variable.hpp.

Public Member Functions
template<typename... Arg>
	Variable (Arg &&... arg)
LockedPtr< std::unique_lock< Mutex >, Data >	UniqueLock ()
LockedPtr< std::unique_lock< Mutex >, const Data >	UniqueLock () const
std::optional< LockedPtr< std::unique_lock< Mutex >, const Data > >	UniqueLock (std::try_to_lock_t) const
std::optional< LockedPtr< std::unique_lock< Mutex >, Data > >	UniqueLock (std::try_to_lock_t)
std::optional< LockedPtr< std::unique_lock< Mutex >, const Data > >	UniqueLock (std::chrono::milliseconds try_duration) const
std::optional< LockedPtr< std::unique_lock< Mutex >, Data > >	UniqueLock (std::chrono::milliseconds try_duration)
LockedPtr< std::shared_lock< Mutex >, const Data >	SharedLock () const
LockedPtr< std::shared_lock< Mutex >, Data >	SharedMutableLockUnsafe ()
LockedPtr< std::lock_guard< Mutex >, Data >	Lock ()
LockedPtr< std::lock_guard< Mutex >, const Data >	Lock () const
Mutex &	GetMutexUnsafe () const
Data &	GetDataUnsafe ()
const Data &	GetDataUnsafe () const

Constructor & Destructor Documentation

Variable()

template<typename Data, typename Mutex = engine::Mutex>

template<typename... Arg>

concurrent::Variable< Data, Mutex >::Variable ( Arg &&... arg )

inline

Definition at line 61 of file variable.hpp.

Member Function Documentation

GetDataUnsafe() [1/2]

template<typename Data, typename Mutex = engine::Mutex>

Data & concurrent::Variable< Data, Mutex >::GetDataUnsafe ( )

inline

Get raw data. Use with extreme caution, only for cases where it is impossible to access data with safe methods (e.g. std::scoped_lock with multiple mutexes). For simple use cases call Lock(), UniqueLock(), SharedLock() instead.

Definition at line 102 of file variable.hpp.

GetDataUnsafe() [2/2]

template<typename Data, typename Mutex = engine::Mutex>

const Data & concurrent::Variable< Data, Mutex >::GetDataUnsafe ( ) const

inline

Definition at line 104 of file variable.hpp.

GetMutexUnsafe()

template<typename Data, typename Mutex = engine::Mutex>

Mutex & concurrent::Variable< Data, Mutex >::GetMutexUnsafe ( ) const

inline

Get raw mutex. Use with caution. For simple use cases call Lock(), UniqueLock(), SharedLock() instead.

Definition at line 96 of file variable.hpp.

Lock() [1/2]

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::lock_guard< Mutex >, Data > concurrent::Variable< Data, Mutex >::Lock ( )

inline

Definition at line 90 of file variable.hpp.

Lock() [2/2]

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::lock_guard< Mutex >, const Data > concurrent::Variable< Data, Mutex >::Lock ( ) const

inline

Definition at line 92 of file variable.hpp.

SharedLock()

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::shared_lock< Mutex >, const Data > concurrent::Variable< Data, Mutex >::SharedLock ( ) const

inline

Definition at line 84 of file variable.hpp.

SharedMutableLockUnsafe()

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::shared_lock< Mutex >, Data > concurrent::Variable< Data, Mutex >::SharedMutableLockUnsafe ( )

inline

Useful for grabbing a reference to an object in a node-based container, e.g. std::unordered_map. Values must support concurrent modification.

Definition at line 88 of file variable.hpp.

UniqueLock() [1/6]

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::unique_lock< Mutex >, Data > concurrent::Variable< Data, Mutex >::UniqueLock ( )

inline

Definition at line 63 of file variable.hpp.

UniqueLock() [2/6]

template<typename Data, typename Mutex = engine::Mutex>

LockedPtr< std::unique_lock< Mutex >, const Data > concurrent::Variable< Data, Mutex >::UniqueLock ( ) const

inline

Definition at line 65 of file variable.hpp.

UniqueLock() [3/6]

template<typename Data, typename Mutex = engine::Mutex>

std::optional< LockedPtr< std::unique_lock< Mutex >, Data > > concurrent::Variable< Data, Mutex >::UniqueLock ( std::chrono::milliseconds try_duration )

inline

Definition at line 80 of file variable.hpp.

UniqueLock() [4/6]

template<typename Data, typename Mutex = engine::Mutex>

std::optional< LockedPtr< std::unique_lock< Mutex >, const Data > > concurrent::Variable< Data, Mutex >::UniqueLock ( std::chrono::milliseconds try_duration ) const

inline

Definition at line 75 of file variable.hpp.

UniqueLock() [5/6]

template<typename Data, typename Mutex = engine::Mutex>

std::optional< LockedPtr< std::unique_lock< Mutex >, Data > > concurrent::Variable< Data, Mutex >::UniqueLock ( std::try_to_lock_t )

inline

Definition at line 71 of file variable.hpp.

UniqueLock() [6/6]

template<typename Data, typename Mutex = engine::Mutex>

std::optional< LockedPtr< std::unique_lock< Mutex >, const Data > > concurrent::Variable< Data, Mutex >::UniqueLock ( std::try_to_lock_t ) const

inline

Definition at line 67 of file variable.hpp.

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The documentation for this class was generated from the following file:

• userver/concurrent/variable.hpp