SharedMemSegment Class Reference

Handles a shared memory segment with metadata (the segment size) More...

#include <sharedmem.h>

Inheritance diagram for SharedMemSegment:

Public Member Functions
	SharedMemSegment (const char *name, std::size_t n_bytes, bool is_server=false)
	Default constructor. More...
virtual	~SharedMemSegment ()
	Default destructor.
virtual std::size_t	getSize ()=0
	Client: return size of payload.
virtual void	put (std::vector< uint8_t > &inp_payload, void *meta_)=0
	Server: copy byte chunk into payload accompanied with metadata. Corrent typecast in child class methods.
virtual void	put (uint8_t *buf_, void *meta_)=0
virtual void	copyMetaFrom (void *meta_)=0
	Dereference metadata pointer correctly and copy the contents into this memory segment's metadata.
virtual void	copyMetaTo (void *meta_)=0
	Dereference metadata pointer correctly and copy the contents from this memory segment's metadata.
void	init ()
	Must be called after construction. Reserves shmem payload and correct metadata (depending on the subclass)
void	close_ ()
	Must be called before destruction. Releases correct amount of metadata bytes (depending on the subclass)
bool	getClientState ()
	Was the shmem acquisition succesfull?

Public Attributes
uint8_t *	payload
	Pointer to payload.
std::size_t	n_bytes
	Maximum size of the payload (this much is reserved)

Protected Member Functions
virtual void	serverInit ()=0
	Server: Uses shmem_open with write rights. used by the constructor if is_server=true. Init with correct metadata serialization.
virtual bool	clientInit ()=0
	Client: Uses shmem_open with read-only rights. Init with correct metadata serialization.
virtual void	serverClose ()=0
	Erases the shmem segment. used by the constructor if is_server=true.
virtual void	clientClose ()=0

Protected Attributes
std::string	name
	Name to identify the posix objects.
std::string	payload_name
	Name to identify the posix memory mapped file.
std::string	meta_name
	Name to identify the posix memory mapped file for the metadata.
bool	is_server
	Client or server process?
void *	ptr
void *	ptr_
	Raw pointers to shared memory.
bool	client_state
	Was the shmem acquisition succesfull?

Detailed Description

Handles a shared memory segment with metadata (the segment size)

First, instantiate a shared memory segment in the server side, with is_server=true

Second, from another process, instantiate shared memory segment with the same name, but with is_server=false

Never instantiate both server and client side from the same process.

This is a virtual class. Child classes should define metadata and its serialization. This is done in serverInit, serverClose, clientInit and clientClose

Constructor & Destructor Documentation

SharedMemSegment()

SharedMemSegment::SharedMemSegment	(	const char *	name,
		std::size_t	n_bytes,
		bool	is_server = false
	)

Default constructor.

Parameters

name	String identifying the shmem segment in the posix shmem system
n_bytes	Size of the byte buffer
is_server	In the server side, instantiate with true, in client side, instantiate with false

---

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

• /home/sampsa/C/valkka/include/sharedmem.h
• /home/sampsa/C/valkka/src/sharedmem.cpp