shmem.h File Reference

#include "utils/hsearch.h"

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Data Structures
struct	ShmemStructOpts
struct	ShmemHashOpts
struct	ShmemCallbacks

Macros
#define	SHMEM_ATTACH_UNKNOWN_SIZE   (-1)
#define	SHMEM_CALLBACKS_ALLOW_AFTER_STARTUP   0x00000001
#define	ShmemRequestStruct(...)    ShmemRequestStructWithOpts(&(ShmemStructOpts){__VA_ARGS__})
#define	ShmemRequestHash(...)    ShmemRequestHashWithOpts(&(ShmemHashOpts){__VA_ARGS__})

Typedefs
typedef struct ShmemStructOpts	ShmemStructOpts
typedef struct ShmemHashOpts	ShmemHashOpts
typedef void(*	ShmemRequestCallback) (void *opaque_arg)
typedef void(*	ShmemInitCallback) (void *opaque_arg)
typedef void(*	ShmemAttachCallback) (void *opaque_arg)
typedef struct ShmemCallbacks	ShmemCallbacks

Functions
void	RegisterShmemCallbacks (const ShmemCallbacks *callbacks)
bool	ShmemAddrIsValid (const void *addr)
void	ShmemRequestStructWithOpts (const ShmemStructOpts *options)
void	ShmemRequestHashWithOpts (const ShmemHashOpts *options)
void *	ShmemInitStruct (const char *name, Size size, bool *foundPtr)
HTAB *	ShmemInitHash (const char *name, int64 nelems, HASHCTL *infoP, int hash_flags)
void *	ShmemAlloc (Size size)
void *	ShmemAllocNoError (Size size)
PGDLLIMPORT Size	pg_get_shmem_pagesize (void)
void	RequestAddinShmemSpace (Size size)

Macro Definition Documentation

SHMEM_ATTACH_UNKNOWN_SIZE

#define SHMEM_ATTACH_UNKNOWN_SIZE   (-1)

Definition at line 69 of file shmem.h.

SHMEM_CALLBACKS_ALLOW_AFTER_STARTUP

#define SHMEM_CALLBACKS_ALLOW_AFTER_STARTUP   0x00000001

Definition at line 167 of file shmem.h.

ShmemRequestHash

#define ShmemRequestHash

(

...

)

ShmemRequestHashWithOpts(&(ShmemHashOpts){__VA_ARGS__})

Definition at line 179 of file shmem.h.

                                             {__VA_ARGS__})

ShmemRequestStruct

#define ShmemRequestStruct

(

...

)

ShmemRequestStructWithOpts(&(ShmemStructOpts){__VA_ARGS__})

Definition at line 176 of file shmem.h.

                                                 {__VA_ARGS__})

Typedef Documentation

ShmemAttachCallback

typedef void(* ShmemAttachCallback) (void *opaque_arg)

Definition at line 114 of file shmem.h.

ShmemCallbacks

typedef struct ShmemCallbacks ShmemCallbacks

ShmemHashOpts

typedef struct ShmemHashOpts ShmemHashOpts

ShmemInitCallback

typedef void(* ShmemInitCallback) (void *opaque_arg)

Definition at line 113 of file shmem.h.

ShmemRequestCallback

typedef void(* ShmemRequestCallback) (void *opaque_arg)

Definition at line 112 of file shmem.h.

ShmemStructOpts

typedef struct ShmemStructOpts ShmemStructOpts

Function Documentation

pg_get_shmem_pagesize()

PGDLLIMPORT Size pg_get_shmem_pagesize ( void  )

extern

Definition at line 1273 of file shmem.c.

{
    Size        os_page_size;
#ifdef WIN32
    SYSTEM_INFO sysinfo;
 
    GetSystemInfo(&sysinfo);
    os_page_size = sysinfo.dwPageSize;
#else
    os_page_size = sysconf(_SC_PAGESIZE);
#endif
 
    Assert(IsUnderPostmaster);
    Assert(huge_pages_status != HUGE_PAGES_UNKNOWN);
 
    if (huge_pages_status == HUGE_PAGES_ON)
        GetHugePageSize(&os_page_size, NULL);
 
    return os_page_size;
}

RegisterShmemCallbacks()

void RegisterShmemCallbacks ( const ShmemCallbacks *  callbacks )

extern

Definition at line 873 of file shmem.c.

{
    if (shmem_request_state == SRS_DONE && IsUnderPostmaster)
    {
        /*
         * After-startup initialization or attachment.  Call the appropriate
         * callbacks immediately.
         */
        if ((callbacks->flags & SHMEM_CALLBACKS_ALLOW_AFTER_STARTUP) == 0)
            elog(ERROR, "cannot request shared memory at this time");
 
        CallShmemCallbacksAfterStartup(callbacks);
    }
    else
    {
        /* Remember the callbacks for later */
        registered_shmem_callbacks = lappend(registered_shmem_callbacks,
                                             (void *) callbacks);
    }
}

References CallShmemCallbacksAfterStartup(), elog, ERROR, ShmemCallbacks::flags, IsUnderPostmaster, lappend(), registered_shmem_callbacks, SHMEM_CALLBACKS_ALLOW_AFTER_STARTUP, and SRS_DONE.

Referenced by _PG_init().

RequestAddinShmemSpace()

void RequestAddinShmemSpace ( Size  size )

extern

Definition at line 45 of file ipci.c.

{
    if (!process_shmem_requests_in_progress)
        elog(FATAL, "cannot request additional shared memory outside shmem_request_hook");
    total_addin_request = add_size(total_addin_request, size);
}

References add_size(), elog, FATAL, process_shmem_requests_in_progress, and total_addin_request.

ShmemAddrIsValid()

bool ShmemAddrIsValid ( const void *  addr )

extern

Definition at line 849 of file shmem.c.

{
    return (addr >= ShmemBase) && (addr < ShmemEnd);
}

References ShmemBase, and ShmemEnd.

Referenced by ReleasePredXact().

ShmemAlloc()

void * ShmemAlloc ( Size  size )

extern

Definition at line 763 of file shmem.c.

{
    void       *newSpace;
    Size        allocated_size;
 
    newSpace = ShmemAllocRaw(size, 0, &allocated_size);
    if (!newSpace)
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory (%zu bytes requested)",
                        size)));
    return newSpace;
}

References ereport, errcode(), errmsg, ERROR, fb(), and ShmemAllocRaw().

Referenced by InitShmemAllocator().

ShmemAllocNoError()

void * ShmemAllocNoError ( Size  size )

extern

Definition at line 783 of file shmem.c.

{
    Size        allocated_size;
 
    return ShmemAllocRaw(size, 0, &allocated_size);
}

References ShmemAllocRaw().

ShmemInitHash()

HTAB * ShmemInitHash ( const char *  name, int64  nelems, HASHCTL *  infoP, int  hash_flags  )

extern

Definition at line 117 of file shmem_hash.c.

{
    bool        found;
    size_t      size;
    void       *location;
 
    size = hash_estimate_size(nelems, infoP->entrysize);
 
    /*
     * Look it up in the shmem index or allocate.
     *
     * NOTE: The area is requested internally as SHMEM_KIND_STRUCT instead of
     * SHMEM_KIND_HASH.  That's correct because we do the hash table
     * initialization by calling shmem_hash_create() ourselves.  (We don't
     * expose the request kind to users; if we did, that would be confusing.)
     */
    location = ShmemInitStruct(name, size, &found);
 
    return shmem_hash_create(location, size, found,
                             name, nelems, infoP, hash_flags);
}

References fb(), hash_estimate_size(), name, shmem_hash_create(), and ShmemInitStruct().

ShmemInitStruct()

void * ShmemInitStruct ( const char *  name, Size  size, bool *  foundPtr  )

extern

Definition at line 1010 of file shmem.c.

{
    void       *ptr = NULL;
    ShmemStructOpts options = {
        .name = name,
        .size = size,
        .ptr = &ptr,
    };
    ShmemRequest request = {&options, SHMEM_KIND_STRUCT};
 
    Assert(shmem_request_state == SRS_DONE ||
           shmem_request_state == SRS_INITIALIZING ||
           shmem_request_state == SRS_REQUESTING);
 
    LWLockAcquire(ShmemIndexLock, LW_EXCLUSIVE);
 
    /*
     * During postmaster startup, look up the existing entry if any.
     */
    *foundPtr = false;
    if (IsUnderPostmaster)
        *foundPtr = AttachShmemIndexEntry(&request, true);
 
    /* Initialize it if not found */
    if (!*foundPtr)
        InitShmemIndexEntry(&request);
 
    LWLockRelease(ShmemIndexLock);
 
    Assert(ptr != NULL);
    return ptr;
}

References Assert, AttachShmemIndexEntry(), fb(), InitShmemIndexEntry(), IsUnderPostmaster, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), name, SHMEM_KIND_STRUCT, ShmemIndexLock, SRS_DONE, SRS_INITIALIZING, and SRS_REQUESTING.

Referenced by ShmemInitHash().

ShmemRequestHashWithOpts()

void ShmemRequestHashWithOpts ( const ShmemHashOpts *  options )

extern

Definition at line 44 of file shmem_hash.c.

{
    ShmemHashOpts *options_copy;
 
    Assert(options->name != NULL);
 
    options_copy = MemoryContextAlloc(TopMemoryContext,
                                      sizeof(ShmemHashOpts));
    memcpy(options_copy, options, sizeof(ShmemHashOpts));
 
    /* Set options for the fixed-size area holding the hash table */
    options_copy->base.name = options->name;
    options_copy->base.size = hash_estimate_size(options_copy->nelems,
                                                 options_copy->hash_info.entrysize);
 
    ShmemRequestInternal(&options_copy->base, SHMEM_KIND_HASH);
}

References Assert, fb(), hash_estimate_size(), memcpy(), MemoryContextAlloc(), SHMEM_KIND_HASH, ShmemRequestInternal(), and TopMemoryContext.

ShmemRequestStructWithOpts()

void ShmemRequestStructWithOpts ( const ShmemStructOpts *  options )

extern

Definition at line 315 of file shmem.c.

{
    ShmemStructOpts *options_copy;
 
    options_copy = MemoryContextAlloc(TopMemoryContext,
                                      sizeof(ShmemStructOpts));
    memcpy(options_copy, options, sizeof(ShmemStructOpts));
 
    ShmemRequestInternal(options_copy, SHMEM_KIND_STRUCT);
}

References fb(), memcpy(), MemoryContextAlloc(), SHMEM_KIND_STRUCT, ShmemRequestInternal(), and TopMemoryContext.