jh::sync::ipc::process_shm_obj< S, T, HighPriv > Class Template Reference

Cross-process shared-memory container for a single POD-like object. More...

#include <jh/synchronous/ipc/process_shm_obj.h>

Public Member Functions
	process_shm_obj (const process_shm_obj &)=delete
process_shm_obj &	operator= (const process_shm_obj &)=delete
T *	ptr () noexcept
	Obtain non-const pointer to the shared object.
const T *	ptr () const noexcept
	Obtain const pointer to the shared object.
T &	ref () noexcept
	Obtain non-const reference to the shared object.
const T &	ref () const noexcept
	Obtain const reference to the shared object.
T *	operator-> () noexcept
	Operator-> convenience accessor.
const T *	operator-> () const noexcept
	Const Operator-> convenience accessor.
T &	operator* () noexcept
	Operator* convenience accessor.
const T &	operator* () const noexcept
	Const Operator* convenience accessor.
lock_t &	lock () noexcept
	Accessor for the inter-process mutex protecting this shared object.

Static Public Member Functions
static process_shm_obj &	instance ()
	Singleton accessor.
static void	flush_acquire () noexcept
	Acquire fence ensuring visibility of preceding writes by other processes.
static void	flush_release () noexcept
	Release fence ensuring visibility of local writes to other processes.
static void	flush_seq () noexcept
	Sequential-consistency fence for full memory ordering.
static void	unlink ()
	Remove the shared-memory region and associated mutexes (POSIX only).
static void	unlink ()=delete
	Disabled if HighPriv == false. Non-privileged variants cannot call unlink().

Detailed Description

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>
requires (limits::valid_object_name<S, limits::max_name_length - 4>())
class jh::sync::ipc::process_shm_obj< S, T, HighPriv >

Cross-process shared-memory container for a single POD-like object.

Provides a memory-mapped instance of T visible to all processes sharing the same name S. Synchronization and initialization are managed internally via named process-level mutexes.

Template Parameters

S	Shared-memory name literal (letters, digits, dot, dash, underscore).
T	POD-like type satisfying cv_free_pod_like.
HighPriv	Enables privileged operations (e.g. unlink()).

Member Function Documentation

flush_acquire()

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

void jh::sync::ipc::process_shm_obj< S, T, HighPriv >::flush_acquire ( )

inlinestaticnoexcept

Acquire fence ensuring visibility of preceding writes by other processes.

Use this before reading from the shared object to guarantee memory ordering.

flush_release()

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

void jh::sync::ipc::process_shm_obj< S, T, HighPriv >::flush_release ( )

inlinestaticnoexcept

Release fence ensuring visibility of local writes to other processes.

Call this before releasing the lock after modifying the shared object.

flush_seq()

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

void jh::sync::ipc::process_shm_obj< S, T, HighPriv >::flush_seq ( )

inlinestaticnoexcept

Sequential-consistency fence for full memory ordering.

Equivalent to std::atomic_thread_fence(std::memory_order_seq_cst).

lock()

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

lock_t & jh::sync::ipc::process_shm_obj< S, T, HighPriv >::lock ( )

inlinenodiscardnoexcept

Accessor for the inter-process mutex protecting this shared object.

Returns

Reference to the internal process_mutex<S + ".loc">.

operator*() [1/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

const T & jh::sync::ipc::process_shm_obj< S, T, HighPriv >::operator* ( ) const

inlinenodiscardnoexcept

Const Operator* convenience accessor.

Returns

Const reference to the shared object.

operator*() [2/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

T & jh::sync::ipc::process_shm_obj< S, T, HighPriv >::operator* ( )

inlinenodiscardnoexcept

Operator* convenience accessor.

Returns

Reference to the shared object.

operator->() [1/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

const T * jh::sync::ipc::process_shm_obj< S, T, HighPriv >::operator-> ( ) const

inlinenodiscardnoexcept

Const Operator-> convenience accessor.

Returns

Const pointer to the shared object.

operator->() [2/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

T * jh::sync::ipc::process_shm_obj< S, T, HighPriv >::operator-> ( )

inlinenodiscardnoexcept

Operator-> convenience accessor.

Returns

Pointer to the shared object.

ptr() [1/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

const T * jh::sync::ipc::process_shm_obj< S, T, HighPriv >::ptr ( ) const

inlinenodiscardnoexcept

Obtain const pointer to the shared object.

Returns

Const pointer to the mapped shared instance.

ptr() [2/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

T * jh::sync::ipc::process_shm_obj< S, T, HighPriv >::ptr ( )

inlinenodiscardnoexcept

Obtain non-const pointer to the shared object.

Returns

Pointer to the mapped shared instance of T.

ref() [1/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

const T & jh::sync::ipc::process_shm_obj< S, T, HighPriv >::ref ( ) const

inlinenodiscardnoexcept

Obtain const reference to the shared object.

Returns

Const reference to the shared instance.

ref() [2/2]

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

T & jh::sync::ipc::process_shm_obj< S, T, HighPriv >::ref ( )

inlinenodiscardnoexcept

Obtain non-const reference to the shared object.

Returns

Reference to the shared instance.

unlink()

template<jh::meta::TStr S, jh::pod::cv_free_pod_like T, bool HighPriv = false>

void jh::sync::ipc::process_shm_obj< S, T, HighPriv >::unlink ( )

inlinestatic

Remove the shared-memory region and associated mutexes (POSIX only).

Semantics

• Calls shm_unlink() for the mapped object name.
• Then removes both process_mutex and process_mutex<S + ".loc">.
• Ignores ENOENT if the object does not exist.
• Throws std::runtime_error on other errors.

Idempotency

The operation is idempotent and safe to call multiple times. Once all processes unmap, the region is destroyed by the OS.

Windows

Windows provides no explicit unlink; shared handles are released automatically when all processes close them.

---

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

• include/jh/synchronous/ipc/process_shm_obj.h