Make a memory pool that is based on System V shared memory (shmget(2) etc.). This implementation allows memory to be shared between processes. If your platform doesn't support System V shared memory (e.g., Win32 and many RTOS platforms do not) then you should use ACE_MMAP_Memory_Pool instead of this class. In fact, you should probably use ACE_MMAP_Memory_Pool on platforms that do support System V shared memory since it provides more powerful features, such as persistent backing store and greatly scalability. More...

#include <Shared_Memory_Pool.h>

Inheritance diagram for ACE_Shared_Memory_Pool:

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Collaboration diagram for ACE_Shared_Memory_Pool:

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List of all members.

Classes
struct	SHM_TABLE
	Keeps track of all the segments being used. More...
Public Types
typedef ACE_Shared_Memory_Pool_Options	OPTIONS
Public Member Functions
	ACE_Shared_Memory_Pool (const ACE_TCHAR backing_store_name=0, const OPTIONS options=0)
	Initialize the pool.
virtual	~ACE_Shared_Memory_Pool (void)
virtual void *	init_acquire (size_t nbytes, size_t &rounded_bytes, int &first_time)
	Ask system for initial chunk of local memory.
virtual void *	acquire (size_t nbytes, size_t &rounded_bytes)
virtual int	release (int destroy=1)
	Instruct the memory pool to release all of its resources.
virtual int	sync (ssize_t len=-1, int flags=MS_SYNC)
virtual int	sync (void *addr, size_t len, int flags=MS_SYNC)
	Sync the memory region to the backing store starting at addr.
virtual int	protect (ssize_t len=-1, int prot=PROT_RDWR)
virtual int	protect (void *addr, size_t len, int prot=PROT_RDWR)
virtual void *	base_addr (void) const
virtual void	dump (void) const
	Dump the state of an object.
Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks.
Protected Member Functions
virtual size_t	round_up (size_t nbytes)
virtual int	commit_backing_store_name (size_t rounded_bytes, ACE_OFF_T &offset)
virtual int	find_seg (const void *const searchPtr, ACE_OFF_T &offset, size_t &counter)
	Find the segment that contains the searchPtr.
virtual int	in_use (ACE_OFF_T &offset, size_t &counter)
	Determine how much memory is currently in use.
virtual int	handle_signal (int signum, siginfo_t , ucontext_t )
Protected Attributes
void *	base_addr_
size_t	file_perms_
	File permissions to use when creating/opening a segment.
size_t	max_segments_
	Number of shared memory segments in the <SHM_TABLE> table.
ACE_OFF_T	minimum_bytes_
	What the minimim bytes of the initial segment should be.
size_t	segment_size_
	Shared memory segment size.
key_t	base_shm_key_
	Base shared memory key for the segment.
ACE_Sig_Handler	signal_handler_
	Handles SIGSEGV.

Detailed Description

Make a memory pool that is based on System V shared memory (shmget(2) etc.). This implementation allows memory to be shared between processes. If your platform doesn't support System V shared memory (e.g., Win32 and many RTOS platforms do not) then you should use ACE_MMAP_Memory_Pool instead of this class. In fact, you should probably use ACE_MMAP_Memory_Pool on platforms that do support System V shared memory since it provides more powerful features, such as persistent backing store and greatly scalability.

Member Typedef Documentation

typedef ACE_Shared_Memory_Pool_Options ACE_Shared_Memory_Pool::OPTIONS

Constructor & Destructor Documentation

ACE_Shared_Memory_Pool::ACE_Shared_Memory_Pool	(	const ACE_TCHAR *	backing_store_name = `0`,
		const OPTIONS *	options = `0`
	)

Initialize the pool.

ACE_Shared_Memory_Pool::~ACE_Shared_Memory_Pool ( void )

virtual

Member Function Documentation

void * ACE_Shared_Memory_Pool::acquire	(	size_t	nbytes,
		size_t &	rounded_bytes
	)

virtual

Acquire at least nbytes from the memory pool. rounded_byes is the actual number of bytes allocated. Also acquires an internal semaphore that ensures proper serialization of Memory_Pool initialization across processes.

void * ACE_Shared_Memory_Pool::base_addr ( void ) const

virtual

Return the base address of this memory pool, 0 if base_addr never changes.

int ACE_Shared_Memory_Pool::commit_backing_store_name	(	size_t	rounded_bytes,
		ACE_OFF_T &	offset
	)

protectedvirtual

Commits a new shared memory segment if necessary after an <acquire> or a signal. offset is set to the new offset into the backing store.

void ACE_Shared_Memory_Pool::dump ( void ) const

virtual

Dump the state of an object.

int ACE_Shared_Memory_Pool::find_seg	(	const void *const	searchPtr,
		ACE_OFF_T &	offset,
		size_t &	counter
	)

protectedvirtual

Find the segment that contains the searchPtr.

int ACE_Shared_Memory_Pool::handle_signal	(	int	signum,
		siginfo_t *	siginfo,
		ucontext_t *
	)

protectedvirtual

Handle SIGSEGV and SIGBUS signals to remap shared memory properly.

Reimplemented from ACE_Event_Handler.

int ACE_Shared_Memory_Pool::in_use	(	ACE_OFF_T &	offset,
		size_t &	counter
	)

protectedvirtual

Determine how much memory is currently in use.

void * ACE_Shared_Memory_Pool::init_acquire	(	size_t	nbytes,
		size_t &	rounded_bytes,
		int &	first_time
	)

virtual

Ask system for initial chunk of local memory.

int ACE_Shared_Memory_Pool::protect	(	ssize_t	len = `-1`,
		int	prot = `PROT_RDWR`
	)

virtual

Change the protection of the pages of the mapped region to prot starting at this->base_addr_ up to len bytes. If len == -1 then change protection of all pages in the mapped region.

int ACE_Shared_Memory_Pool::protect	(	void *	addr,
		size_t	len,
		int	prot = `PROT_RDWR`
	)

virtual

Change the protection of the pages of the mapped region to prot starting at addr up to len bytes.

int ACE_Shared_Memory_Pool::release ( int destroy = 1 )

virtual

Instruct the memory pool to release all of its resources.

size_t ACE_Shared_Memory_Pool::round_up ( size_t nbytes )

protectedvirtual

Implement the algorithm for rounding up the request to an appropriate chunksize.

int ACE_Shared_Memory_Pool::sync	(	ssize_t	len = `-1`,
		int	flags = `MS_SYNC`
	)

virtual

Sync the memory region to the backing store starting at this->base_addr_.

int ACE_Shared_Memory_Pool::sync	(	void *	addr,
		size_t	len,
		int	flags = `MS_SYNC`
	)

virtual

Sync the memory region to the backing store starting at addr.

Member Data Documentation

ACE_Shared_Memory_Pool::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

void* ACE_Shared_Memory_Pool::base_addr_

protected

Base address of the shared memory segment. If this has the value of 0 then the OS is free to select any address, otherwise this value is what the OS must try to use to map the shared memory segment.

key_t ACE_Shared_Memory_Pool::base_shm_key_

protected

Base shared memory key for the segment.

size_t ACE_Shared_Memory_Pool::file_perms_

protected

File permissions to use when creating/opening a segment.

size_t ACE_Shared_Memory_Pool::max_segments_

protected

Number of shared memory segments in the <SHM_TABLE> table.

ACE_OFF_T ACE_Shared_Memory_Pool::minimum_bytes_

protected

What the minimim bytes of the initial segment should be.