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// -*- C++ -*-
//=============================================================================
/**
* @file Shared_Memory_Pool.h
*
* @author Dougls C. Schmidt <d.schmidt@vanderbilt.edu>
* @author Prashant Jain <pjain@cs.wustl.edu>
*/
//=============================================================================
#ifndef ACE_SHARED_MEMORY_POOL_H
#define ACE_SHARED_MEMORY_POOL_H
#include /**/ "ace/pre.h"
#include /**/ "ace/ACE_export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#if !defined (ACE_LACKS_SYSV_SHMEM)
#include "ace/ACE.h"
#include "ace/Event_Handler.h"
#include "ace/Sig_Handler.h"
#include "ace/os_include/sys/os_mman.h"
ACE_BEGIN_VERSIONED_NAMESPACE_DECL
/**
* @class ACE_Shared_Memory_Pool_Options
*
* @brief Helper class for Shared Memory Pool constructor options.
*
* This should be a nested class, but that breaks too many
* compilers.
*/
class ACE_Export ACE_Shared_Memory_Pool_Options
{
public:
/// Initialization method.
ACE_Shared_Memory_Pool_Options (
const char *base_addr = ACE_DEFAULT_BASE_ADDR,
size_t max_segments = ACE_DEFAULT_MAX_SEGMENTS,
size_t file_perms = ACE_DEFAULT_FILE_PERMS,
ACE_OFF_T minimum_bytes = 0,
size_t segment_size = ACE_DEFAULT_SEGMENT_SIZE);
/// Base address of the memory-mapped backing store.
const char *base_addr_;
/// Number of shared memory segments to allocate.
size_t max_segments_;
/// What the minimum bytes of the initial segment should be.
ACE_OFF_T minimum_bytes_;
/// File permissions to use when creating/opening a segment.
size_t file_perms_;
/// Shared memory segment size.
size_t segment_size_;
};
/**
* @class ACE_Shared_Memory_Pool
*
* @brief 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.
*/
class ACE_Export ACE_Shared_Memory_Pool : public ACE_Event_Handler
{
public:
typedef ACE_Shared_Memory_Pool_Options OPTIONS;
/// Initialize the pool.
ACE_Shared_Memory_Pool (const ACE_TCHAR *backing_store_name = 0,
const OPTIONS *options = 0);
virtual ~ACE_Shared_Memory_Pool (void);
/// Ask system for initial chunk of local memory.
virtual void *init_acquire (size_t nbytes,
size_t &rounded_bytes,
int &first_time);
/**
* Acquire at least @a nbytes from the memory pool. @a rounded_byes is
* the actual number of bytes allocated. Also acquires an internal
* semaphore that ensures proper serialization of Memory_Pool
* initialization across processes.
*/
virtual void *acquire (size_t nbytes,
size_t &rounded_bytes);
/// Instruct the memory pool to release all of its resources.
virtual int release (int destroy = 1);
/// Sync the memory region to the backing store starting at
/// @c this->base_addr_.
virtual int sync (ssize_t len = -1, int flags = MS_SYNC);
/// Sync the memory region to the backing store starting at @a addr.
virtual int sync (void *addr, size_t len, int flags = MS_SYNC);
/**
* Change the protection of the pages of the mapped region to @a prot
* starting at @c this->base_addr_ up to @a len bytes. If @a len == -1
* then change protection of all pages in the mapped region.
*/
virtual int protect (ssize_t len = -1, int prot = PROT_RDWR);
/// Change the protection of the pages of the mapped region to @a prot
/// starting at @a addr up to @a len bytes.
virtual int protect (void *addr, size_t len, int prot = PROT_RDWR);
/// Return the base address of this memory pool, 0 if base_addr
/// never changes.
virtual void *base_addr () const;
/// Dump the state of an object.
virtual void dump () const;
/// Declare the dynamic allocation hooks.
ACE_ALLOC_HOOK_DECLARE;
protected:
/// Implement the algorithm for rounding up the request to an
/// appropriate chunksize.
virtual size_t round_up (size_t nbytes);
/**
* Commits a new shared memory segment if necessary after an
* acquire() or a signal. @a offset is set to the new offset into
* the backing store.
*/
virtual int commit_backing_store_name (size_t rounded_bytes,
ACE_OFF_T &offset);
/// Keeps track of all the segments being used.
struct SHM_TABLE
{
/// Shared memory segment key.
key_t key_;
/// Shared memory segment internal id.
int shmid_;
/// Is the segment currently used.;
int used_;
};
/**
* 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.
*/
void *base_addr_;
/// File permissions to use when creating/opening a segment.
size_t file_perms_;
/// Number of shared memory segments in the <SHM_TABLE> table.
size_t max_segments_;
/// What the minimim bytes of the initial segment should be.
ACE_OFF_T minimum_bytes_;
/// Shared memory segment size.
size_t segment_size_;
/// Base shared memory key for the segment.
key_t base_shm_key_;
/// Find the segment that contains the @a searchPtr
virtual int find_seg (const void *const searchPtr,
ACE_OFF_T &offset,
size_t &counter);
/// Determine how much memory is currently in use.
virtual int in_use (ACE_OFF_T &offset,
size_t &counter);
/// Handles SIGSEGV.
ACE_Sig_Handler signal_handler_;
/// Handle SIGSEGV and SIGBUS signals to remap shared memory
/// properly.
virtual int handle_signal (int, siginfo_t *siginfo, ucontext_t *);
};
ACE_END_VERSIONED_NAMESPACE_DECL
#endif /* !ACE_LACKS_SYSV_SHMEM */
#include /**/ "ace/post.h"
#endif /* ACE_SHARED_MEMORY_POOL_H */
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