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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Classes
struct	SHM_TABLE
	Keeps track of all the segments being used. More...

Public Types
typedef ACE_Shared_Memory_Pool_Options	OPTIONS

Public Types inherited from ACE_Event_Handler
enum	{ LO_PRIORITY = 0 , HI_PRIORITY = 10 , NULL_MASK = 0 , READ_MASK = (1 << 0) , WRITE_MASK = (1 << 1) , EXCEPT_MASK = (1 << 2) , ACCEPT_MASK = (1 << 3) , CONNECT_MASK = (1 << 4) , TIMER_MASK = (1 << 5) , QOS_MASK = (1 << 6) , GROUP_QOS_MASK = (1 << 7) , SIGNAL_MASK = (1 << 8) , ALL_EVENTS_MASK , RWE_MASK , DONT_CALL = (1 << 9) }

enum	{ ACE_EVENT_HANDLER_NOT_RESUMED = -1 , ACE_REACTOR_RESUMES_HANDLER = 0 , ACE_APPLICATION_RESUMES_HANDLER }

typedef long	Reference_Count
	Reference count type. More...

Public Member Functions
	ACE_Shared_Memory_Pool (const ACE_TCHAR backing_store_name=0, const OPTIONS options=0)
	Initialize the pool. More...

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. More...

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. More...

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. More...

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 () const

virtual void	dump () const
	Dump the state of an object. More...

Public Member Functions inherited from ACE_Event_Handler
virtual	~ACE_Event_Handler ()=default
	Destructor is virtual to enable proper cleanup. More...

virtual ACE_HANDLE	get_handle () const
	Get the I/O handle. More...

virtual void	set_handle (ACE_HANDLE)
	Set the I/O handle. More...

virtual int	priority () const

virtual void	priority (int priority)
	Set the priority of the Event_Handler. More...

virtual int	handle_input (ACE_HANDLE fd=ACE_INVALID_HANDLE)
	Called when input events occur (e.g., connection or data). More...

virtual int	handle_output (ACE_HANDLE fd=ACE_INVALID_HANDLE)

virtual int	handle_exception (ACE_HANDLE fd=ACE_INVALID_HANDLE)
	Called when an exceptional events occur (e.g., SIGURG). More...

virtual int	handle_timeout (const ACE_Time_Value &current_time, const void *act=0)

virtual int	handle_exit (ACE_Process *)
	Called when a process exits. More...

virtual int	handle_close (ACE_HANDLE handle, ACE_Reactor_Mask close_mask)

virtual int	resume_handler ()

virtual int	handle_qos (ACE_HANDLE=ACE_INVALID_HANDLE)

virtual int	handle_group_qos (ACE_HANDLE=ACE_INVALID_HANDLE)

virtual void	reactor (ACE_Reactor *reactor)
	Set the event demultiplexors. More...

virtual ACE_Reactor *	reactor () const
	Get the event demultiplexors. More...

virtual ACE_Reactor_Timer_Interface *	reactor_timer_interface () const
	Get only the reactor's timer related interface. More...

virtual Reference_Count	add_reference ()
	Increment reference count on the handler. More...

virtual Reference_Count	remove_reference ()
	Decrement reference count on the handler. More...

Reference_Counting_Policy &	reference_counting_policy ()
	Current Reference_Counting_Policy. More...

Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks. More...

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. More...

virtual int	in_use (ACE_OFF_T &offset, size_t &counter)
	Determine how much memory is currently in use. More...

virtual int	handle_signal (int, siginfo_t siginfo, ucontext_t )
	Handle SIGSEGV and SIGBUS signals to remap shared memory properly. More...

Protected Member Functions inherited from ACE_Event_Handler
	ACE_Event_Handler (ACE_Reactor *=nullptr, int priority=ACE_Event_Handler::LO_PRIORITY)
	Force ACE_Event_Handler to be an abstract base class. More...

Protected Attributes
void *	base_addr_

size_t	file_perms_
	File permissions to use when creating/opening a segment. More...

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

ACE_OFF_T	minimum_bytes_
	What the minimim bytes of the initial segment should be. More...

size_t	segment_size_
	Shared memory segment size. More...

key_t	base_shm_key_
	Base shared memory key for the segment. More...

ACE_Sig_Handler	signal_handler_
	Handles SIGSEGV. More...

Protected Attributes inherited from ACE_Event_Handler
Atomic_Reference_Count	reference_count_
	Reference count. More...

Additional Inherited Members
Static Public Member Functions inherited from ACE_Event_Handler
static ACE_THR_FUNC_RETURN	read_adapter (void *event_handler)

static int	register_stdin_handler (ACE_Event_Handler eh, ACE_Reactor reactor, ACE_Thread_Manager *thr_mgr, int flags=THR_DETACHED)

static int	remove_stdin_handler (ACE_Reactor reactor, ACE_Thread_Manager thr_mgr)
	Performs the inverse of the register_stdin_handler() method. More...

Protected Types inherited from ACE_Event_Handler
typedef std::atomic< Reference_Count >	Atomic_Reference_Count
	Typedef for implementation of reference counting. More...

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

◆ OPTIONS

typedef ACE_Shared_Memory_Pool_Options ACE_Shared_Memory_Pool::OPTIONS

Constructor & Destructor Documentation

◆ ACE_Shared_Memory_Pool()

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::~ACE_Shared_Memory_Pool ( void )

virtual

Member Function Documentation

◆ acquire()

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.

◆ base_addr()

void * ACE_Shared_Memory_Pool::base_addr ( ) const

virtual

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

◆ commit_backing_store_name()

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.

◆ dump()

void ACE_Shared_Memory_Pool::dump ( void ) const

virtual

Dump the state of an object.

◆ find_seg()

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.

◆ handle_signal()

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

protectedvirtual

Handle SIGSEGV and SIGBUS signals to remap shared memory properly.

Reimplemented from ACE_Event_Handler.

◆ in_use()

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

protectedvirtual

Determine how much memory is currently in use.

◆ init_acquire()

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.

◆ protect() [1/2]

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.

◆ protect() [2/2]

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.

◆ release()

int ACE_Shared_Memory_Pool::release ( int destroy = 1 )

virtual

Instruct the memory pool to release all of its resources.

◆ round_up()

size_t ACE_Shared_Memory_Pool::round_up ( size_t nbytes )

protectedvirtual

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

◆ sync() [1/2]

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_.

◆ sync() [2/2]

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_ALLOC_HOOK_DECLARE

ACE_Shared_Memory_Pool::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

◆ base_addr_

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.

◆ base_shm_key_

key_t ACE_Shared_Memory_Pool::base_shm_key_

protected

Base shared memory key for the segment.

◆ file_perms_

size_t ACE_Shared_Memory_Pool::file_perms_

protected

File permissions to use when creating/opening a segment.

◆ max_segments_

size_t ACE_Shared_Memory_Pool::max_segments_

protected

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

◆ minimum_bytes_

ACE_OFF_T ACE_Shared_Memory_Pool::minimum_bytes_

protected

What the minimim bytes of the initial segment should be.

◆ segment_size_

size_t ACE_Shared_Memory_Pool::segment_size_

protected

Shared memory segment size.

◆ signal_handler_

ACE_Sig_Handler ACE_Shared_Memory_Pool::signal_handler_

protected

Handles SIGSEGV.

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

Classes

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ OPTIONS

Constructor & Destructor Documentation

◆ ACE_Shared_Memory_Pool()

◆ ~ACE_Shared_Memory_Pool()

Member Function Documentation

◆ acquire()

◆ base_addr()

◆ commit_backing_store_name()

◆ dump()

◆ find_seg()

◆ handle_signal()

◆ in_use()

◆ init_acquire()

◆ protect() [1/2]

◆ protect() [2/2]

◆ release()

◆ round_up()

◆ sync() [1/2]

◆ sync() [2/2]

Member Data Documentation

◆ ACE_ALLOC_HOOK_DECLARE

◆ base_addr_

◆ base_shm_key_

◆ file_perms_

◆ max_segments_

◆ minimum_bytes_

◆ segment_size_

◆ signal_handler_