pmem::obj::shared_mutex Class Reference

Persistent memory resident shared_mutex implementation. More...

#include <libpmemobj++/shared_mutex.hpp>

Public Types
typedef PMEMrwlock *	native_handle_type
	Implementation defined handle to the native type.

Public Member Functions
	shared_mutex ()
	Default constructor. More...
	~shared_mutex ()=default
	Defaulted destructor.
void	lock ()
	Lock the mutex for exclusive access. More...
void	lock_shared ()
	Lock the mutex for shared access. More...
bool	try_lock ()
	Try to lock the mutex for exclusive access, returns regardless if the lock succeeds. More...
bool	try_lock_shared ()
	Try to lock the mutex for shared access, returns regardless if the lock succeeds. More...
void	unlock ()
	Unlocks the mutex. More...
void	unlock_shared ()
	Unlocks the mutex. More...
native_handle_type	native_handle () noexcept
	Access a native handle to this shared mutex. More...
enum pobj_tx_param	lock_type () const noexcept
	The type of lock needed for the transaction API. More...
shared_mutex &	operator= (const shared_mutex &)=delete
	Deleted assignment operator.
	shared_mutex (const shared_mutex &)=delete
	Deleted copy constructor.

Private Attributes
PMEMrwlock	plock
	A POSIX style PMEM-resident shared_mutex.

Detailed Description

Persistent memory resident shared_mutex implementation.

This class is an implementation of a PMEM-resident share_mutex which mimics in behavior the C++11 std::mutex. This class satisfies all requirements of the SharedMutex and StandardLayoutType concepts. The typical usage would be:

#include <libpmemobj++/persistent_ptr.hpp>
#include <libpmemobj++/pool.hpp>
#include <libpmemobj++/shared_mutex.hpp>
#include <mutex>
 
namespace nvobj = pmem::obj;
 
void
shared_mutex_example()
{
    // pool root structure
    struct root {
        nvobj::shared_mutex pmutex;
    };
 
    // create a pmemobj pool
    auto pop = nvobj::pool<root>::create("poolfile", "layout",
                         PMEMOBJ_MIN_POOL);
    auto proot = pop.root();
 
    // typical usage schemes
    proot->pmutex.lock_shared();
 
    std::unique_lock<nvobj::shared_mutex> guard(proot->pmutex);
}

Constructor & Destructor Documentation

shared_mutex()

pmem::obj::shared_mutex::shared_mutex ( )

inline

Default constructor.

Exceptions

lock_error

when the shared_mutex is not from persistent memory.

Member Function Documentation

lock()

void pmem::obj::shared_mutex::lock ( )

inline

Lock the mutex for exclusive access.

If a different thread already locked this mutex, the calling thread will block. If the same thread tries to lock a mutex it already owns, either in exclusive or shared mode, the behavior is undefined.

Exceptions

lock_error

when an error occurs, this includes all system related errors with the underlying implementation of the mutex.

lock_shared()

void pmem::obj::shared_mutex::lock_shared ( )

inline

Lock the mutex for shared access.

If a different thread already locked this mutex for exclusive access, the calling thread will block. If it was locked for shared access by a different thread, the lock will succeed.

The mutex can be locked for shared access multiple times by the same thread. If so, the same number of unlocks must be made to unlock the mutex.

Exceptions

lock_error

when an error occurs, this includes all system related errors with the underlying implementation of the mutex.

lock_type()

enum pobj_tx_param pmem::obj::shared_mutex::lock_type ( ) const

inlinenoexcept

The type of lock needed for the transaction API.

Returns

TX_PARAM_RWLOCK

native_handle()

native_handle_type pmem::obj::shared_mutex::native_handle ( )

inlinenoexcept

Access a native handle to this shared mutex.

Returns

a pointer to PMEMmutex.

try_lock()

bool pmem::obj::shared_mutex::try_lock ( )

inline

Try to lock the mutex for exclusive access, returns regardless if the lock succeeds.

If the same thread tries to lock a mutex it already owns either in exclusive or shared mode, the behavior is undefined.

Returns

true on successful lock acquisition, false otherwise.

Exceptions

lock_error

when an error occurs, this includes all system related errors with the underlying implementation of the mutex.

try_lock_shared()

bool pmem::obj::shared_mutex::try_lock_shared ( )

inline

Try to lock the mutex for shared access, returns regardless if the lock succeeds.

The mutex can be locked for shared access multiple times by the same thread. If so, the same number of unlocks must be made to unlock the mutex. If the calling thread already owns the mutex in any mode, the behavior is undefined.

Returns

false if a different thread already locked the mutex for exclusive access, true otherwise.

Exceptions

lock_error

when an error occurs, this includes all system related errors with the underlying implementation of the mutex.

unlock()

void pmem::obj::shared_mutex::unlock ( )

inline

Unlocks the mutex.

The mutex must be locked for exclusive access by the calling thread, otherwise results in undefined behavior.

unlock_shared()

void pmem::obj::shared_mutex::unlock_shared ( )

inline

Unlocks the mutex.

The mutex must be locked for shared access by the calling thread, otherwise results in undefined behavior.

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

• libpmemobj++/shared_mutex.hpp