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Harden xxx_is_visible() functions against concurrent object drops.

Browse Source 
For the same reasons given in commit 403ac226d, adjust these
functions to not assume that checking SearchSysCacheExists can
guarantee success of a later fetch.

This follows the same internal API choices made in the earlier commit:
add a function XXXExt(oid, is_missing) and use that to eliminate
the need for a separate existence check.  The changes are very
straightforward, though tedious.  For the moment I just made the new
functions static in namespace.c, but we could export them if a need
emerges.

Per bug #18014 from Alexander Lakhin.  Given the lack of hard evidence
that there's a bug in non-debug builds, I'm content to fix this only
in HEAD.

Discussion: https://postgr.es/m/18014-28c81cb79d44295d@postgresql.org
This commit is contained in:
Tom Lane 2023-10-14 16:13:11 -04:00
parent 403ac226dd
commit fcdd6689d0
2 changed files with 343 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

387
src/backend/catalog/namespace.c
View File

@ -183,6 +183,19 @@ char *namespace_search_path = NULL;
/* Local functions */
static bool RelationIsVisibleExt(Oid relid, bool *is_missing);
static bool TypeIsVisibleExt(Oid typid, bool *is_missing);
static bool FunctionIsVisibleExt(Oid funcid, bool *is_missing);
static bool OperatorIsVisibleExt(Oid oprid, bool *is_missing);
static bool OpclassIsVisibleExt(Oid opcid, bool *is_missing);
static bool OpfamilyIsVisibleExt(Oid opfid, bool *is_missing);
static bool CollationIsVisibleExt(Oid collid, bool *is_missing);
static bool ConversionIsVisibleExt(Oid conid, bool *is_missing);
static bool StatisticsObjIsVisibleExt(Oid stxid, bool *is_missing);
static bool TSParserIsVisibleExt(Oid prsId, bool *is_missing);
static bool TSDictionaryIsVisibleExt(Oid dictId, bool *is_missing);
static bool TSTemplateIsVisibleExt(Oid tmplId, bool *is_missing);
static bool TSConfigIsVisibleExt(Oid cfgid, bool *is_missing);
static void recomputeNamespacePath(void);
static void AccessTempTableNamespace(bool force);
static void InitTempTableNamespace(void);
@ -691,6 +704,18 @@ RelnameGetRelid(const char *relname)
*/
bool
RelationIsVisible(Oid relid)
{
return RelationIsVisibleExt(relid, NULL);
}
/*
* RelationIsVisibleExt
* As above, but if the relation isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
RelationIsVisibleExt(Oid relid, bool *is_missing)
{
HeapTuple reltup;
Form_pg_class relform;
@ -699,7 +724,14 @@ RelationIsVisible(Oid relid)
reltup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(reltup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for relation %u", relid);
}
relform = (Form_pg_class) GETSTRUCT(reltup);
recomputeNamespacePath();
@ -799,6 +831,18 @@ TypenameGetTypidExtended(const char *typname, bool temp_ok)
*/
bool
TypeIsVisible(Oid typid)
{
return TypeIsVisibleExt(typid, NULL);
}
/*
* TypeIsVisibleExt
* As above, but if the type isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
TypeIsVisibleExt(Oid typid, bool *is_missing)
{
HeapTuple typtup;
Form_pg_type typform;
@ -807,7 +851,14 @@ TypeIsVisible(Oid typid)
typtup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
if (!HeapTupleIsValid(typtup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for type %u", typid);
}
typform = (Form_pg_type) GETSTRUCT(typtup);
recomputeNamespacePath();
@ -1436,6 +1487,18 @@ MatchNamedCall(HeapTuple proctup, int nargs, List *argnames,
*/
bool
FunctionIsVisible(Oid funcid)
{
return FunctionIsVisibleExt(funcid, NULL);
}
/*
* FunctionIsVisibleExt
* As above, but if the function isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
FunctionIsVisibleExt(Oid funcid, bool *is_missing)
{
HeapTuple proctup;
Form_pg_proc procform;
@ -1444,7 +1507,14 @@ FunctionIsVisible(Oid funcid)
proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
if (!HeapTupleIsValid(proctup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for function %u", funcid);
}
procform = (Form_pg_proc) GETSTRUCT(proctup);
recomputeNamespacePath();
@ -1770,6 +1840,18 @@ OpernameGetCandidates(List *names, char oprkind, bool missing_schema_ok)
*/
bool
OperatorIsVisible(Oid oprid)
{
return OperatorIsVisibleExt(oprid, NULL);
}
/*
* OperatorIsVisibleExt
* As above, but if the operator isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
OperatorIsVisibleExt(Oid oprid, bool *is_missing)
{
HeapTuple oprtup;
Form_pg_operator oprform;
@ -1778,7 +1860,14 @@ OperatorIsVisible(Oid oprid)
oprtup = SearchSysCache1(OPEROID, ObjectIdGetDatum(oprid));
if (!HeapTupleIsValid(oprtup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for operator %u", oprid);
}
oprform = (Form_pg_operator) GETSTRUCT(oprtup);
recomputeNamespacePath();
@ -1856,6 +1945,18 @@ OpclassnameGetOpcid(Oid amid, const char *opcname)
*/
bool
OpclassIsVisible(Oid opcid)
{
return OpclassIsVisibleExt(opcid, NULL);
}
/*
* OpclassIsVisibleExt
* As above, but if the opclass isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
OpclassIsVisibleExt(Oid opcid, bool *is_missing)
{
HeapTuple opctup;
Form_pg_opclass opcform;
@ -1864,7 +1965,14 @@ OpclassIsVisible(Oid opcid)
opctup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opcid));
if (!HeapTupleIsValid(opctup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for opclass %u", opcid);
}
opcform = (Form_pg_opclass) GETSTRUCT(opctup);
recomputeNamespacePath();
@ -1939,6 +2047,18 @@ OpfamilynameGetOpfid(Oid amid, const char *opfname)
*/
bool
OpfamilyIsVisible(Oid opfid)
{
return OpfamilyIsVisibleExt(opfid, NULL);
}
/*
* OpfamilyIsVisibleExt
* As above, but if the opfamily isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
OpfamilyIsVisibleExt(Oid opfid, bool *is_missing)
{
HeapTuple opftup;
Form_pg_opfamily opfform;
@ -1947,7 +2067,14 @@ OpfamilyIsVisible(Oid opfid)
opftup = SearchSysCache1(OPFAMILYOID, ObjectIdGetDatum(opfid));
if (!HeapTupleIsValid(opftup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for opfamily %u", opfid);
}
opfform = (Form_pg_opfamily) GETSTRUCT(opftup);
recomputeNamespacePath();
@ -2071,6 +2198,18 @@ CollationGetCollid(const char *collname)
*/
bool
CollationIsVisible(Oid collid)
{
return CollationIsVisibleExt(collid, NULL);
}
/*
* CollationIsVisibleExt
* As above, but if the collation isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
CollationIsVisibleExt(Oid collid, bool *is_missing)
{
HeapTuple colltup;
Form_pg_collation collform;
@ -2079,7 +2218,14 @@ CollationIsVisible(Oid collid)
colltup = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
if (!HeapTupleIsValid(colltup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for collation %u", collid);
}
collform = (Form_pg_collation) GETSTRUCT(colltup);
recomputeNamespacePath();
@ -2154,6 +2300,18 @@ ConversionGetConid(const char *conname)
*/
bool
ConversionIsVisible(Oid conid)
{
return ConversionIsVisibleExt(conid, NULL);
}
/*
* ConversionIsVisibleExt
* As above, but if the conversion isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
ConversionIsVisibleExt(Oid conid, bool *is_missing)
{
HeapTuple contup;
Form_pg_conversion conform;
@ -2162,7 +2320,14 @@ ConversionIsVisible(Oid conid)
contup = SearchSysCache1(CONVOID, ObjectIdGetDatum(conid));
if (!HeapTupleIsValid(contup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for conversion %u", conid);
}
conform = (Form_pg_conversion) GETSTRUCT(contup);
recomputeNamespacePath();
@ -2257,16 +2422,35 @@ get_statistics_object_oid(List *names, bool missing_ok)
* for the unqualified statistics object name".
*/
bool
StatisticsObjIsVisible(Oid relid)
StatisticsObjIsVisible(Oid stxid)
{
return StatisticsObjIsVisibleExt(stxid, NULL);
}
/*
* StatisticsObjIsVisibleExt
* As above, but if the statistics object isn't found and is_missing is
* not NULL, then set *is_missing = true and return false instead of
* throwing an error. (Caller must initialize *is_missing = false.)
*/
static bool
StatisticsObjIsVisibleExt(Oid stxid, bool *is_missing)
{
HeapTuple stxtup;
Form_pg_statistic_ext stxform;
Oid stxnamespace;
bool visible;
stxtup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(relid));
stxtup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(stxid));
if (!HeapTupleIsValid(stxtup))
elog(ERROR, "cache lookup failed for statistics object %u", relid);
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for statistics object %u", stxid);
}
stxform = (Form_pg_statistic_ext) GETSTRUCT(stxtup);
recomputeNamespacePath();
@ -2381,6 +2565,18 @@ get_ts_parser_oid(List *names, bool missing_ok)
*/
bool
TSParserIsVisible(Oid prsId)
{
return TSParserIsVisibleExt(prsId, NULL);
}
/*
* TSParserIsVisibleExt
* As above, but if the parser isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
TSParserIsVisibleExt(Oid prsId, bool *is_missing)
{
HeapTuple tup;
Form_pg_ts_parser form;
@ -2389,7 +2585,14 @@ TSParserIsVisible(Oid prsId)
tup = SearchSysCache1(TSPARSEROID, ObjectIdGetDatum(prsId));
if (!HeapTupleIsValid(tup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for text search parser %u", prsId);
}
form = (Form_pg_ts_parser) GETSTRUCT(tup);
recomputeNamespacePath();
@ -2507,6 +2710,18 @@ get_ts_dict_oid(List *names, bool missing_ok)
*/
bool
TSDictionaryIsVisible(Oid dictId)
{
return TSDictionaryIsVisibleExt(dictId, NULL);
}
/*
* TSDictionaryIsVisibleExt
* As above, but if the dictionary isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
TSDictionaryIsVisibleExt(Oid dictId, bool *is_missing)
{
HeapTuple tup;
Form_pg_ts_dict form;
@ -2515,8 +2730,15 @@ TSDictionaryIsVisible(Oid dictId)
tup = SearchSysCache1(TSDICTOID, ObjectIdGetDatum(dictId));
if (!HeapTupleIsValid(tup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for text search dictionary %u",
dictId);
}
form = (Form_pg_ts_dict) GETSTRUCT(tup);
recomputeNamespacePath();
@ -2634,6 +2856,18 @@ get_ts_template_oid(List *names, bool missing_ok)
*/
bool
TSTemplateIsVisible(Oid tmplId)
{
return TSTemplateIsVisibleExt(tmplId, NULL);
}
/*
* TSTemplateIsVisibleExt
* As above, but if the template isn't found and is_missing is not NULL,
* then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
TSTemplateIsVisibleExt(Oid tmplId, bool *is_missing)
{
HeapTuple tup;
Form_pg_ts_template form;
@ -2642,7 +2876,14 @@ TSTemplateIsVisible(Oid tmplId)
tup = SearchSysCache1(TSTEMPLATEOID, ObjectIdGetDatum(tmplId));
if (!HeapTupleIsValid(tup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for text search template %u", tmplId);
}
form = (Form_pg_ts_template) GETSTRUCT(tup);
recomputeNamespacePath();
@ -2760,6 +3001,18 @@ get_ts_config_oid(List *names, bool missing_ok)
*/
bool
TSConfigIsVisible(Oid cfgid)
{
return TSConfigIsVisibleExt(cfgid, NULL);
}
/*
* TSConfigIsVisibleExt
* As above, but if the configuration isn't found and is_missing is not
* NULL, then set *is_missing = true and return false instead of throwing
* an error. (Caller must initialize *is_missing = false.)
*/
static bool
TSConfigIsVisibleExt(Oid cfgid, bool *is_missing)
{
HeapTuple tup;
Form_pg_ts_config form;
@ -2768,8 +3021,15 @@ TSConfigIsVisible(Oid cfgid)
tup = SearchSysCache1(TSCONFIGOID, ObjectIdGetDatum(cfgid));
if (!HeapTupleIsValid(tup))
{
if (is_missing != NULL)
{
*is_missing = true;
return false;
}
elog(ERROR, "cache lookup failed for text search configuration %u",
cfgid);
}
form = (Form_pg_ts_config) GETSTRUCT(tup);
recomputeNamespacePath();
@ -4283,152 +4543,189 @@ fetch_search_path_array(Oid *sarray, int sarray_len)
* condition errors when a query that's scanning a catalog using an MVCC
* snapshot uses one of these functions. The underlying IsVisible functions
* always use an up-to-date snapshot and so might see the object as already
* gone when it's still visible to the transaction snapshot. (There is no race
* condition in the current coding because we don't accept sinval messages
* between the SearchSysCacheExists test and the subsequent lookup.)
* gone when it's still visible to the transaction snapshot.
*/
Datum
pg_table_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(oid)))
result = RelationIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(RelationIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_type_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(TYPEOID, ObjectIdGetDatum(oid)))
result = TypeIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(TypeIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_function_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(PROCOID, ObjectIdGetDatum(oid)))
result = FunctionIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(FunctionIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_operator_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(OPEROID, ObjectIdGetDatum(oid)))
result = OperatorIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(OperatorIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_opclass_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(CLAOID, ObjectIdGetDatum(oid)))
result = OpclassIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(OpclassIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_opfamily_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(OPFAMILYOID, ObjectIdGetDatum(oid)))
result = OpfamilyIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(OpfamilyIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_collation_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(COLLOID, ObjectIdGetDatum(oid)))
result = CollationIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(CollationIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_conversion_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(CONVOID, ObjectIdGetDatum(oid)))
result = ConversionIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(ConversionIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_statistics_obj_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(STATEXTOID, ObjectIdGetDatum(oid)))
result = StatisticsObjIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(StatisticsObjIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_ts_parser_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(TSPARSEROID, ObjectIdGetDatum(oid)))
result = TSParserIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(TSParserIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_ts_dict_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(TSDICTOID, ObjectIdGetDatum(oid)))
result = TSDictionaryIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(TSDictionaryIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_ts_template_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(TSTEMPLATEOID, ObjectIdGetDatum(oid)))
result = TSTemplateIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(TSTemplateIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum
pg_ts_config_is_visible(PG_FUNCTION_ARGS)
{
Oid oid = PG_GETARG_OID(0);
bool result;
bool is_missing = false;
if (!SearchSysCacheExists1(TSCONFIGOID, ObjectIdGetDatum(oid)))
result = TSConfigIsVisibleExt(oid, &is_missing);
if (is_missing)
PG_RETURN_NULL();
PG_RETURN_BOOL(TSConfigIsVisible(oid));
PG_RETURN_BOOL(result);
}
Datum

2
src/include/catalog/namespace.h
View File

@ -122,7 +122,7 @@ extern Oid ConversionGetConid(const char *conname);
extern bool ConversionIsVisible(Oid conid);
extern Oid get_statistics_object_oid(List *names, bool missing_ok);
extern bool StatisticsObjIsVisible(Oid relid);
extern bool StatisticsObjIsVisible(Oid stxid);
extern Oid get_ts_parser_oid(List *names, bool missing_ok);
extern bool TSParserIsVisible(Oid prsId);