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ShmMemoryGrp Class Reference

The ShmMemoryGrp concrete class provides an implementation of MsgMemoryGrp. More...

#include <memshm.h>

Inheritance diagram for ShmMemoryGrp

[legend]Collaboration diagram for ShmMemoryGrp:

[legend]List of all members.

Public Methods
	ShmMemoryGrp (const Ref< MessageGrp > &msg)
	ShmMemoryGrp (const Ref< KeyVal > &)
	~ShmMemoryGrp ()
void	set_localsize (int)
	Set the size of locally held memory. More...
void*	localdata ()
	Returns a pointer to the local data.
void*	obtain_readwrite (distsize_t offset, int size)
	Only one thread can have an unreleased obtain_readwrite at a time. More...
void*	obtain_readonly (distsize_t offset, int size)
	This gives read access to the memory location. No locking is done.
void*	obtain_writeonly (distsize_t offset, int size)
	This gives write access to the memory location. No locking is done.
void	release_readonly (void *data, distsize_t offset, int size)
	This is called when read access is no longer needed.
void	release_writeonly (void *data, distsize_t offset, int size)
	This is called when write access is no longer needed.
void	release_readwrite (void *data, distsize_t offset, int size)
	This is called when read/write access is no longer needed. More...
void	print (std::ostream &o=ExEnv::out()) const
	Prints out information about the object.

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Detailed Description

The ShmMemoryGrp concrete class provides an implementation of MsgMemoryGrp.

It uses SYSV IPC to provided shared memory in a system that provide shared memory in hardware. It is very fast and reliable.

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Member Function Documentation

void* ShmMemoryGrp::obtain_readwrite ( distsize_t offset, int size ) [virtual]

Only one thread can have an unreleased obtain_readwrite at a time. The actual memory region locked can be larger than that requested. If the memory region is already locked this will block. For this reason, data should be held as read/write for as short a time as possible. Reimplemented from MemoryGrp.

void ShmMemoryGrp::release_readwrite ( void * data, distsize_t offset, int size ) [virtual]

This is called when read/write access is no longer needed. The memory will be unlocked. Reimplemented from MemoryGrp.

void ShmMemoryGrp::set_localsize ( int localsize ) [virtual]

Set the size of locally held memory. When memory is accessed using a global offset counting starts at node 0 and proceeds up to node n() - 1. Reimplemented from MsgMemoryGrp.

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

• memshm.h

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