mlib::shmem_base Class Reference

Base class for shared memory objects. More...

#include <shmem.h>

Inheritance diagram for mlib::shmem_base:

Public Member Functions
	shmem_base ()
	Default constructor.
	shmem_base (const std::string &name, size_t size)
	Create and open a SMA.
virtual	~shmem_base ()
	Destructor.
virtual bool	open (const std::string &name, size_t size)
	Open a SMA.
virtual bool	close ()
	Close a SMA.
bool	created () const
bool	is_opened () const
	Return true if shared memory is opened.
size_t	size () const
	Return size of shared memory area.
const std::string &	name () const
	Return the name of the shared memory area.
void	wtmo (DWORD msec)
	Set timeout value for write operations.
DWORD	wtmo () const
	Return current write timeout value (in milliseconds)
void	rtmo (DWORD msec)
	Set timeout value for read operations.
DWORD	rtmo () const
	Return current timeout value for read operations (in milliseconds)
virtual bool	write (const void *data)
	Obtain writer lock and update SMA.
virtual bool	read (void *data)
	Obtain a reader lock and retrieve SMA content.

Protected Member Functions
virtual bool	rdlock ()
	Obtain a reader lock on SMA.
virtual void	rdunlock ()
	Release a previously obtained reader lock.
virtual bool	wrlock ()
	Obtain a writer lock on SMA.
virtual void	wrunlock ()
	Release a previously obtained writer lock.
Naked data access functions
Use always together with lock control functions
void	get (void *data) const
	Retrieve current content of SMA.
void	put (const void *data)
	Write new data into the SMA.
const void *	dataptr () const
	Return a pointer to content of SMA (const variant)
void *	dataptr ()
	Return a pointer to content of SMA (non-const variant)

Detailed Description

Base class for shared memory objects.

Constructor & Destructor Documentation

shmem_base() [1/2]

mlib::shmem_base::shmem_base

(

)

Default constructor.

The shared memory area (SMA) must be opened before use.

shmem_base() [2/2]

mlib::shmem_base::shmem_base	(	const std::string &	nam,
		size_t	sz_ )

Create and open a SMA.

Parameters

nam	name of SMA
sz_	size of SMA (not including size of synchronization stuff)

~shmem_base()

mlib::shmem_base::~shmem_base ( )

virtual

Destructor.

If SMA was opened, close it now.

Member Function Documentation

created()

bool mlib::shmem_base::created ( ) const

inline

Return true if this instance has created the shared memory area or false if shared memory existed already.

open()

bool mlib::shmem_base::open ( const std::string & nam, size_t sz_ )

virtual

Open a SMA.

Parameters

nam	name of SMA
sz_	size of SMA (not including size of synchronization stuff)

The SMA is called <nam>.MEM. Additionally, the following objects are created:

• event flag <nam>.EVT
• Mutex <nam>.MUT

rdlock()

bool mlib::shmem_base::rdlock ( )

protectedvirtual

Obtain a reader lock on SMA.

Returns

true if successful, false otherwise

If a write operation is in progress, the function waits for it to complete before acquiring read lock. If it cannot obtain the lock in read timeout set, the function returns false.

read()

bool mlib::shmem_base::read ( void * pData )

virtual

Obtain a reader lock and retrieve SMA content.

Parameters

pData

pointer to data

write()

bool mlib::shmem_base::write ( const void * pData )

virtual

Obtain writer lock and update SMA.

Parameters

pData

pointer to data to write in SMA

wrlock()

bool mlib::shmem_base::wrlock ( )

protectedvirtual

Obtain a writer lock on SMA.

Returns

true if successful, false otherwise

If another operation is in progress, the function waits for it to complete before acquiring write lock. If it cannot obtain the lock in write timeout set, the function returns false.

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

• include/mlib/shmem.h
• src/shmem.cpp