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Introduce pg_dsm_registry_allocations view.

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This commit adds a new system view that provides information about
entries in the dynamic shared memory (DSM) registry.  Specifically,
it returns the name, type, and size of each entry.  Note that since
we cannot discover the size of dynamic shared memory areas (DSAs)
and hash tables backed by DSAs (dshashes) without first attaching
to them, the size column is left as NULL for those.

Bumps catversion.

Author: Florents Tselai <florents.tselai@gmail.com>
Reviewed-by: Sungwoo Chang <swchangdev@gmail.com>
Discussion: https://postgr.es/m/4D445D3E-81C5-4135-95BB-D414204A0AB4%40gmail.com
This commit is contained in:
Nathan Bossart
2025-07-09 09:17:56 -05:00
parent f5a987c0e5
commit 167ed8082f
10 changed files with 187 additions and 3 deletions
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49
src/backend/storage/ipc/dsm_registry.c
View File

@@ -40,10 +40,12 @@
#include "postgres.h"
#include "funcapi.h"
#include "lib/dshash.h"
#include "storage/dsm_registry.h"
#include "storage/lwlock.h"
#include "storage/shmem.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#define DSMR_NAME_LEN 128
@@ -88,6 +90,13 @@ typedef enum DSMREntryType
DSMR_ENTRY_TYPE_DSH,
} DSMREntryType;
static const char *const DSMREntryTypeNames[] =
{
[DSMR_ENTRY_TYPE_DSM] = "segment",
[DSMR_ENTRY_TYPE_DSA] = "area",
[DSMR_ENTRY_TYPE_DSH] = "hash",
};
typedef struct DSMRegistryEntry
{
char name[DSMR_NAME_LEN];
@@ -435,3 +444,43 @@ GetNamedDSHash(const char *name, const dshash_parameters *params, bool *found)
return ret;
}
Datum
pg_get_dsm_registry_allocations(PG_FUNCTION_ARGS)
{
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
DSMRegistryEntry *entry;
MemoryContext oldcontext;
dshash_seq_status status;
InitMaterializedSRF(fcinfo, MAT_SRF_USE_EXPECTED_DESC);
/* Be sure any local memory allocated by DSM/DSA routines is persistent. */
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
init_dsm_registry();
MemoryContextSwitchTo(oldcontext);
dshash_seq_init(&status, dsm_registry_table, false);
while ((entry = dshash_seq_next(&status)) != NULL)
{
Datum vals[3];
bool nulls[3] = {0};
vals[0] = CStringGetTextDatum(entry->name);
vals[1] = CStringGetTextDatum(DSMREntryTypeNames[entry->type]);
/*
* Since we can't know the size of DSA/dshash entries without first
* attaching to them, return NULL for those.
*/
if (entry->type == DSMR_ENTRY_TYPE_DSM)
vals[2] = Int64GetDatum(entry->data.dsm.size);
else
nulls[2] = true;
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, vals, nulls);
}
dshash_seq_term(&status);
return (Datum) 0;
}