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Prepare DSM registry for upcoming changes to LWLock tranche names.

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A proposed patch would place a limit of NAMEDATALEN-1 (i.e., 63)
bytes on the names of dynamically-allocated LWLock tranches, but
GetNamedDSA() and GetNamedDSHash() may register tranches with
longer names.  This commit lowers the maximum DSM registry entry
name length to NAMEDATALEN-1 bytes and modifies GetNamedDSHash() to
create only one tranche, thereby allowing us to keep the DSM
registry's tranche names below NAMEDATALEN bytes.

Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/aKzIg1JryN1qhNuy%40nathan
This commit is contained in:
Nathan Bossart
2025-08-29 20:34:53 -05:00
parent f727b63e81
commit 5487058b56
1 changed files with 19 additions and 38 deletions
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57
src/backend/storage/ipc/dsm_registry.c
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@@ -48,12 +48,6 @@
#include "utils/builtins.h"
#include "utils/memutils.h"
#define DSMR_NAME_LEN 128
#define DSMR_DSA_TRANCHE_SUFFIX " DSA"
#define DSMR_DSA_TRANCHE_SUFFIX_LEN (sizeof(DSMR_DSA_TRANCHE_SUFFIX) - 1)
#define DSMR_DSA_TRANCHE_NAME_LEN (DSMR_NAME_LEN + DSMR_DSA_TRANCHE_SUFFIX_LEN)
typedef struct DSMRegistryCtxStruct
{
dsa_handle dsah;
@@ -72,15 +66,13 @@ typedef struct NamedDSAState
{
dsa_handle handle;
int tranche;
char tranche_name[DSMR_DSA_TRANCHE_NAME_LEN];
} NamedDSAState;
typedef struct NamedDSHState
{
NamedDSAState dsa;
dshash_table_handle handle;
dsa_handle dsa_handle;
dshash_table_handle dsh_handle;
int tranche;
char tranche_name[DSMR_NAME_LEN];
} NamedDSHState;
typedef enum DSMREntryType
@@ -99,7 +91,7 @@ static const char *const DSMREntryTypeNames[] =
typedef struct DSMRegistryEntry
{
char name[DSMR_NAME_LEN];
char name[NAMEDATALEN];
DSMREntryType type;
union
{
@@ -308,8 +300,7 @@ GetNamedDSA(const char *name, bool *found)
/* Initialize the LWLock tranche for the DSA. */
state->tranche = LWLockNewTrancheId();
strcpy(state->tranche_name, name);
LWLockRegisterTranche(state->tranche, state->tranche_name);
LWLockRegisterTranche(state->tranche, name);
/* Initialize the DSA. */
ret = dsa_create(state->tranche);
@@ -331,7 +322,7 @@ GetNamedDSA(const char *name, bool *found)
(errmsg("requested DSA already attached to current process")));
/* Initialize existing LWLock tranche for the DSA. */
LWLockRegisterTranche(state->tranche, state->tranche_name);
LWLockRegisterTranche(state->tranche, name);
/* Attach to existing DSA. */
ret = dsa_attach(state->handle);
@@ -348,11 +339,10 @@ GetNamedDSA(const char *name, bool *found)
* Initialize or attach a named dshash table.
*
* This routine returns the address of the table. The tranche_id member of
* params is ignored; new tranche IDs will be generated if needed. Note that
* the DSA lock tranche will be registered with the provided name with " DSA"
* appended. The dshash lock tranche will be registered with the provided
* name. Also note that this should be called at most once for a given table
* in each backend.
* params is ignored; a new LWLock tranche ID will be generated if needed.
* Note that the lock tranche will be registered with the provided name. Also
* note that this should be called at most once for a given table in each
* backend.
*/
dshash_table *
GetNamedDSHash(const char *name, const dshash_parameters *params, bool *found)
@@ -381,25 +371,18 @@ GetNamedDSHash(const char *name, const dshash_parameters *params, bool *found)
entry = dshash_find_or_insert(dsm_registry_table, name, found);
if (!(*found))
{
NamedDSAState *dsa_state = &entry->data.dsh.dsa;
NamedDSHState *dsh_state = &entry->data.dsh;
dshash_parameters params_copy;
dsa_area *dsa;
entry->type = DSMR_ENTRY_TYPE_DSH;
/* Initialize the LWLock tranche for the DSA. */
dsa_state->tranche = LWLockNewTrancheId();
sprintf(dsa_state->tranche_name, "%s%s", name, DSMR_DSA_TRANCHE_SUFFIX);
LWLockRegisterTranche(dsa_state->tranche, dsa_state->tranche_name);
/* Initialize the LWLock tranche for the dshash table. */
/* Initialize the LWLock tranche for the hash table. */
dsh_state->tranche = LWLockNewTrancheId();
strcpy(dsh_state->tranche_name, name);
LWLockRegisterTranche(dsh_state->tranche, dsh_state->tranche_name);
LWLockRegisterTranche(dsh_state->tranche, name);
/* Initialize the DSA for the hash table. */
dsa = dsa_create(dsa_state->tranche);
dsa = dsa_create(dsh_state->tranche);
dsa_pin(dsa);
dsa_pin_mapping(dsa);
@@ -409,34 +392,32 @@ GetNamedDSHash(const char *name, const dshash_parameters *params, bool *found)
ret = dshash_create(dsa, &params_copy, NULL);
/* Store handles for other backends to use. */
dsa_state->handle = dsa_get_handle(dsa);
dsh_state->handle = dshash_get_hash_table_handle(ret);
dsh_state->dsa_handle = dsa_get_handle(dsa);
dsh_state->dsh_handle = dshash_get_hash_table_handle(ret);
}
else if (entry->type != DSMR_ENTRY_TYPE_DSH)
ereport(ERROR,
(errmsg("requested DSHash does not match type of existing entry")));
else
{
NamedDSAState *dsa_state = &entry->data.dsh.dsa;
NamedDSHState *dsh_state = &entry->data.dsh;
dsa_area *dsa;
/* XXX: Should we verify params matches what table was created with? */
if (dsa_is_attached(dsa_state->handle))
if (dsa_is_attached(dsh_state->dsa_handle))
ereport(ERROR,
(errmsg("requested DSHash already attached to current process")));
/* Initialize existing LWLock tranches for the DSA and dshash table. */
LWLockRegisterTranche(dsa_state->tranche, dsa_state->tranche_name);
LWLockRegisterTranche(dsh_state->tranche, dsh_state->tranche_name);
/* Initialize existing LWLock tranche for the hash table. */
LWLockRegisterTranche(dsh_state->tranche, name);
/* Attach to existing DSA for the hash table. */
dsa = dsa_attach(dsa_state->handle);
dsa = dsa_attach(dsh_state->dsa_handle);
dsa_pin_mapping(dsa);
/* Attach to existing dshash table. */
ret = dshash_attach(dsa, params, dsh_state->handle, NULL);
ret = dshash_attach(dsa, params, dsh_state->dsh_handle, NULL);
}
dshash_release_lock(dsm_registry_table, entry);