dsm_registry.c File Reference

#include "postgres.h"
#include "lib/dshash.h"
#include "storage/dsm_registry.h"
#include "storage/lwlock.h"
#include "storage/shmem.h"
#include "utils/memutils.h"

Include dependency graph for dsm_registry.c:

Go to the source code of this file.

Data Structures
struct	DSMRegistryCtxStruct
struct	DSMRegistryEntry

Typedefs
typedef struct DSMRegistryCtxStruct	DSMRegistryCtxStruct
typedef struct DSMRegistryEntry	DSMRegistryEntry

Functions
Size	DSMRegistryShmemSize (void)
void	DSMRegistryShmemInit (void)
static void	init_dsm_registry (void)
void *	GetNamedDSMSegment (const char *name, size_t size, void(*init_callback)(void *ptr), bool *found)

Variables
static DSMRegistryCtxStruct *	DSMRegistryCtx
static const dshash_parameters	dsh_params
static dsa_area *	dsm_registry_dsa
static dshash_table *	dsm_registry_table

Typedef Documentation

DSMRegistryCtxStruct

typedef struct DSMRegistryCtxStruct DSMRegistryCtxStruct

DSMRegistryEntry

typedef struct DSMRegistryEntry DSMRegistryEntry

Function Documentation

DSMRegistryShmemInit()

void DSMRegistryShmemInit

(

void

)

Definition at line 69 of file dsm_registry.c.

{
    bool        found;
 
    DSMRegistryCtx = (DSMRegistryCtxStruct *)
        ShmemInitStruct("DSM Registry Data",
                        DSMRegistryShmemSize(),
                        &found);
 
    if (!found)
    {
        DSMRegistryCtx->dsah = DSA_HANDLE_INVALID;
        DSMRegistryCtx->dshh = DSHASH_HANDLE_INVALID;
    }
}

References DSA_HANDLE_INVALID, DSMRegistryCtxStruct::dsah, DSHASH_HANDLE_INVALID, DSMRegistryCtxStruct::dshh, DSMRegistryCtx, DSMRegistryShmemSize(), and ShmemInitStruct().

Referenced by CreateOrAttachShmemStructs().

DSMRegistryShmemSize()

Size DSMRegistryShmemSize

(

void

)

Definition at line 63 of file dsm_registry.c.

{
    return MAXALIGN(sizeof(DSMRegistryCtxStruct));
}

References MAXALIGN.

Referenced by CalculateShmemSize(), and DSMRegistryShmemInit().

GetNamedDSMSegment()

void* GetNamedDSMSegment	(	const char *	name,
		size_t	size,
		void(*)(void *ptr)	init_callback,
		bool *	found
	)

Definition at line 131 of file dsm_registry.c.

{
    DSMRegistryEntry *entry;
    MemoryContext oldcontext;
    void       *ret;
 
    Assert(found);
 
    if (!name || *name == '\0')
        ereport(ERROR,
                (errmsg("DSM segment name cannot be empty")));
 
    if (strlen(name) >= offsetof(DSMRegistryEntry, handle))
        ereport(ERROR,
                (errmsg("DSM segment name too long")));
 
    if (size == 0)
        ereport(ERROR,
                (errmsg("DSM segment size must be nonzero")));
 
    /* Be sure any local memory allocated by DSM/DSA routines is persistent. */
    oldcontext = MemoryContextSwitchTo(TopMemoryContext);
 
    /* Connect to the registry. */
    init_dsm_registry();
 
    entry = dshash_find_or_insert(dsm_registry_table, name, found);
    if (!(*found))
    {
        /* Initialize the segment. */
        dsm_segment *seg = dsm_create(size, 0);
 
        dsm_pin_segment(seg);
        dsm_pin_mapping(seg);
        entry->handle = dsm_segment_handle(seg);
        entry->size = size;
        ret = dsm_segment_address(seg);
 
        if (init_callback)
            (*init_callback) (ret);
    }
    else if (entry->size != size)
    {
        ereport(ERROR,
                (errmsg("requested DSM segment size does not match size of "
                        "existing segment")));
    }
    else
    {
        dsm_segment *seg = dsm_find_mapping(entry->handle);
 
        /* If the existing segment is not already attached, attach it now. */
        if (seg == NULL)
        {
            seg = dsm_attach(entry->handle);
            if (seg == NULL)
                elog(ERROR, "could not map dynamic shared memory segment");
 
            dsm_pin_mapping(seg);
        }
 
        ret = dsm_segment_address(seg);
    }
 
    dshash_release_lock(dsm_registry_table, entry);
    MemoryContextSwitchTo(oldcontext);
 
    return ret;
}

References Assert, dshash_find_or_insert(), dshash_release_lock(), dsm_attach(), dsm_create(), dsm_find_mapping(), dsm_pin_mapping(), dsm_pin_segment(), dsm_registry_table, dsm_segment_address(), dsm_segment_handle(), elog, ereport, errmsg(), ERROR, DSMRegistryEntry::handle, init_dsm_registry(), MemoryContextSwitchTo(), name, DSMRegistryEntry::size, size, and TopMemoryContext.

Referenced by apw_init_shmem(), injection_init_shmem(), and tdr_attach_shmem().

init_dsm_registry()

static void init_dsm_registry ( void  )

static

Definition at line 91 of file dsm_registry.c.

{
    /* Quick exit if we already did this. */
    if (dsm_registry_table)
        return;
 
    /* Otherwise, use a lock to ensure only one process creates the table. */
    LWLockAcquire(DSMRegistryLock, LW_EXCLUSIVE);
 
    if (DSMRegistryCtx->dshh == DSHASH_HANDLE_INVALID)
    {
        /* Initialize dynamic shared hash table for registry. */
        dsm_registry_dsa = dsa_create(LWTRANCHE_DSM_REGISTRY_DSA);
        dsa_pin(dsm_registry_dsa);
        dsa_pin_mapping(dsm_registry_dsa);
        dsm_registry_table = dshash_create(dsm_registry_dsa, &dsh_params, NULL);
 
        /* Store handles in shared memory for other backends to use. */
        DSMRegistryCtx->dsah = dsa_get_handle(dsm_registry_dsa);
        DSMRegistryCtx->dshh = dshash_get_hash_table_handle(dsm_registry_table);
    }
    else
    {
        /* Attach to existing dynamic shared hash table. */
        dsm_registry_dsa = dsa_attach(DSMRegistryCtx->dsah);
        dsa_pin_mapping(dsm_registry_dsa);
        dsm_registry_table = dshash_attach(dsm_registry_dsa, &dsh_params,
                                           DSMRegistryCtx->dshh, NULL);
    }
 
    LWLockRelease(DSMRegistryLock);
}

References dsa_attach(), dsa_create, dsa_get_handle(), dsa_pin(), dsa_pin_mapping(), DSMRegistryCtxStruct::dsah, dsh_params, dshash_attach(), dshash_create(), dshash_get_hash_table_handle(), DSHASH_HANDLE_INVALID, DSMRegistryCtxStruct::dshh, dsm_registry_dsa, dsm_registry_table, DSMRegistryCtx, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), and LWTRANCHE_DSM_REGISTRY_DSA.

Referenced by GetNamedDSMSegment().

Variable Documentation

dsh_params

const dshash_parameters dsh_params

static

Initial value:

= {
    offsetof(DSMRegistryEntry, handle),
    sizeof(DSMRegistryEntry),
    dshash_strcmp,
    dshash_strhash,
    dshash_strcpy,
    LWTRANCHE_DSM_REGISTRY_HASH
}

Definition at line 50 of file dsm_registry.c.

Referenced by init_dsm_registry().

dsm_registry_dsa

dsa_area* dsm_registry_dsa

static

Definition at line 59 of file dsm_registry.c.

Referenced by init_dsm_registry().

dsm_registry_table

dshash_table* dsm_registry_table

static

Definition at line 60 of file dsm_registry.c.

Referenced by GetNamedDSMSegment(), and init_dsm_registry().

DSMRegistryCtx

DSMRegistryCtxStruct* DSMRegistryCtx

static

Definition at line 41 of file dsm_registry.c.

Referenced by DSMRegistryShmemInit(), and init_dsm_registry().