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ACE_Shared_Memory_Pool Class Reference

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 <Memory_Pool.h>

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List of all members.

Public Types

typedef ACE_Shared_Memory_Pool_Options OPTIONS

Public Methods

 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 Methods

virtual size_t round_up (size_t nbytes)
virtual int commit_backing_store_name (size_t rounded_bytes, off_t &offset)
virtual int find_seg (const void *const searchPtr, off_t &offset, size_t &counter)
 Find the segment that contains the searchPtr.

virtual int in_use (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.

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_INLINE 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_BYTES is the actual number of bytes allocated. Also acquires an internal semaphore that ensures proper serialization of Memory_Pool initialization across processes.

ACE_INLINE 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,
off_t &    offset
)  [protected, virtual]
 

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,
off_t &    offset,
size_t &    counter
)  [protected, virtual]
 

Find the segment that contains the searchPtr.

int ACE_Shared_Memory_Pool::handle_signal (  int    signum,
siginfo_t *   ,
ucontext_t *   
)  [protected, virtual]
 

Handle SIGSEGV and SIGBUS signals to remap shared memory properly.

Reimplemented from ACE_Event_Handler.

int ACE_Shared_Memory_Pool::in_use (  off_t &    offset,
size_t &    counter
)  [protected, virtual]
 

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.

ACE_INLINE 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.

ACE_INLINE 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::release (  int    destroy = 1 )  [virtual]
 

Instruct the memory pool to release all of its resources.

ACE_INLINE size_t ACE_Shared_Memory_Pool::round_up (  size_t    nbytes )  [protected, virtual]
 

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

ACE_INLINE 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_>.

ACE_INLINE 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_>.

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.

off_t ACE_Shared_Memory_Pool::minimum_bytes_ [protected]
 

What the minimim bytes of the initial segment should be.

size_t ACE_Shared_Memory_Pool::segment_size_ [protected]
 

Shared memory segment size.

ACE_Sig_Handler ACE_Shared_Memory_Pool::signal_handler_ [protected]
 

Handles SIGSEGV.

The documentation for this class was generated from the following files:
Generated on Wed Jan 14 22:47:51 2004 for ACE by doxygen1.2.18