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Commit5c625a9

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Add a hash table to cache lookups of 'C'-language functions (that is,
dynamically loaded C functions). Some limited testing suggests thatthis puts the lookup speed for external functions just about on parwith built-in functions. Per discussion with Eric Ridge.
1 parent90d1465 commit5c625a9

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3 files changed

+165
-30
lines changed

3 files changed

+165
-30
lines changed

‎src/backend/utils/fmgr/dfmgr.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/fmgr/dfmgr.c,v 1.68 2004/01/07 18:56:29 neilc Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/fmgr/dfmgr.c,v 1.69 2004/01/19 02:06:41 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -213,6 +213,7 @@ load_file(char *filename)
213213
prv->next=nxt;
214214
else
215215
file_list=nxt;
216+
clear_external_function_hash(file_scanner->handle);
216217
pg_dlclose(file_scanner->handle);
217218
free((char*)file_scanner);
218219
/* prv does not change */

‎src/backend/utils/fmgr/fmgr.c

Lines changed: 161 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.79 2004/01/07 18:56:29 neilc Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.80 2004/01/19 02:06:41 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -57,11 +57,29 @@ typedef struct
5757
* toastable datatype? */
5858
}Oldstyle_fnextra;
5959

60+
/*
61+
* Hashtable for fast lookup of external C functions
62+
*/
63+
typedefstruct
64+
{
65+
/* fn_oid is the hash key and so must be first! */
66+
Oidfn_oid;/* OID of an external C function */
67+
TransactionIdfn_xmin;/* for checking up-to-dateness */
68+
CommandIdfn_cmin;
69+
PGFunctionuser_fn;/* the function's address */
70+
Pg_finfo_record*inforec;/* address of its info record */
71+
}CFuncHashTabEntry;
72+
73+
staticHTAB*CFuncHash=NULL;
74+
6075

6176
staticvoidfmgr_info_cxt_security(OidfunctionId,FmgrInfo*finfo,MemoryContextmcxt,
6277
boolignore_security);
6378
staticvoidfmgr_info_C_lang(OidfunctionId,FmgrInfo*finfo,HeapTupleprocedureTuple);
6479
staticvoidfmgr_info_other_lang(OidfunctionId,FmgrInfo*finfo,HeapTupleprocedureTuple);
80+
staticCFuncHashTabEntry*lookup_C_func(HeapTupleprocedureTuple);
81+
staticvoidrecord_C_func(HeapTupleprocedureTuple,
82+
PGFunctionuser_fn,Pg_finfo_record*inforec);
6583
staticDatumfmgr_oldstyle(PG_FUNCTION_ARGS);
6684
staticDatumfmgr_security_definer(PG_FUNCTION_ARGS);
6785

@@ -258,36 +276,58 @@ static void
258276
fmgr_info_C_lang(OidfunctionId,FmgrInfo*finfo,HeapTupleprocedureTuple)
259277
{
260278
Form_pg_procprocedureStruct= (Form_pg_proc)GETSTRUCT(procedureTuple);
261-
Datumprosrcattr,
262-
probinattr;
263-
char*prosrcstring,
264-
*probinstring;
265-
void*libraryhandle;
279+
CFuncHashTabEntry*hashentry;
266280
PGFunctionuser_fn;
267281
Pg_finfo_record*inforec;
268282
Oldstyle_fnextra*fnextra;
269283
boolisnull;
270284
inti;
271285

272-
/* Get prosrc and probin strings (link symbol and library filename) */
273-
prosrcattr=SysCacheGetAttr(PROCOID,procedureTuple,
274-
Anum_pg_proc_prosrc,&isnull);
275-
if (isnull)
276-
elog(ERROR,"null prosrc for function %u",functionId);
277-
prosrcstring=DatumGetCString(DirectFunctionCall1(textout,prosrcattr));
278-
279-
probinattr=SysCacheGetAttr(PROCOID,procedureTuple,
280-
Anum_pg_proc_probin,&isnull);
281-
if (isnull)
282-
elog(ERROR,"null probin for function %u",functionId);
283-
probinstring=DatumGetCString(DirectFunctionCall1(textout,probinattr));
284-
285-
/* Look up the function itself */
286-
user_fn=load_external_function(probinstring,prosrcstring, true,
287-
&libraryhandle);
288-
289-
/* Get the function information record (real or default) */
290-
inforec=fetch_finfo_record(libraryhandle,prosrcstring);
286+
/*
287+
* See if we have the function address cached already
288+
*/
289+
hashentry=lookup_C_func(procedureTuple);
290+
if (hashentry)
291+
{
292+
user_fn=hashentry->user_fn;
293+
inforec=hashentry->inforec;
294+
}
295+
else
296+
{
297+
Datumprosrcattr,
298+
probinattr;
299+
char*prosrcstring,
300+
*probinstring;
301+
void*libraryhandle;
302+
303+
/* Get prosrc and probin strings (link symbol and library filename) */
304+
prosrcattr=SysCacheGetAttr(PROCOID,procedureTuple,
305+
Anum_pg_proc_prosrc,&isnull);
306+
if (isnull)
307+
elog(ERROR,"null prosrc for function %u",functionId);
308+
prosrcstring=DatumGetCString(DirectFunctionCall1(textout,
309+
prosrcattr));
310+
311+
probinattr=SysCacheGetAttr(PROCOID,procedureTuple,
312+
Anum_pg_proc_probin,&isnull);
313+
if (isnull)
314+
elog(ERROR,"null probin for function %u",functionId);
315+
probinstring=DatumGetCString(DirectFunctionCall1(textout,
316+
probinattr));
317+
318+
/* Look up the function itself */
319+
user_fn=load_external_function(probinstring,prosrcstring, true,
320+
&libraryhandle);
321+
322+
/* Get the function information record (real or default) */
323+
inforec=fetch_finfo_record(libraryhandle,prosrcstring);
324+
325+
/* Cache the addresses for later calls */
326+
record_C_func(procedureTuple,user_fn,inforec);
327+
328+
pfree(prosrcstring);
329+
pfree(probinstring);
330+
}
291331

292332
switch (inforec->api_version)
293333
{
@@ -315,9 +355,6 @@ fmgr_info_C_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
315355
inforec->api_version);
316356
break;
317357
}
318-
319-
pfree(prosrcstring);
320-
pfree(probinstring);
321358
}
322359

323360
/*
@@ -416,6 +453,102 @@ fetch_finfo_record(void *filehandle, char *funcname)
416453
}
417454

418455

456+
/*-------------------------------------------------------------------------
457+
*Routines for caching lookup information for external C functions.
458+
*
459+
* The routines in dfmgr.c are relatively slow, so we try to avoid running
460+
* them more than once per external function per session. We use a hash table
461+
* with the function OID as the lookup key.
462+
*-------------------------------------------------------------------------
463+
*/
464+
465+
/*
466+
* lookup_C_func: try to find a C function in the hash table
467+
*
468+
* If an entry exists and is up to date, return it; else return NULL
469+
*/
470+
staticCFuncHashTabEntry*
471+
lookup_C_func(HeapTupleprocedureTuple)
472+
{
473+
Oidfn_oid=HeapTupleGetOid(procedureTuple);
474+
CFuncHashTabEntry*entry;
475+
476+
if (CFuncHash==NULL)
477+
returnNULL;/* no table yet */
478+
entry= (CFuncHashTabEntry*)
479+
hash_search(CFuncHash,
480+
&fn_oid,
481+
HASH_FIND,
482+
NULL);
483+
if (entry==NULL)
484+
returnNULL;/* no such entry */
485+
if (entry->fn_xmin==HeapTupleHeaderGetXmin(procedureTuple->t_data)&&
486+
entry->fn_cmin==HeapTupleHeaderGetCmin(procedureTuple->t_data))
487+
returnentry;/* OK */
488+
returnNULL;/* entry is out of date */
489+
}
490+
491+
/*
492+
* record_C_func: enter (or update) info about a C function in the hash table
493+
*/
494+
staticvoid
495+
record_C_func(HeapTupleprocedureTuple,
496+
PGFunctionuser_fn,Pg_finfo_record*inforec)
497+
{
498+
Oidfn_oid=HeapTupleGetOid(procedureTuple);
499+
CFuncHashTabEntry*entry;
500+
boolfound;
501+
502+
/* Create the hash table if it doesn't exist yet */
503+
if (CFuncHash==NULL)
504+
{
505+
HASHCTLhash_ctl;
506+
507+
MemSet(&hash_ctl,0,sizeof(hash_ctl));
508+
hash_ctl.keysize=sizeof(Oid);
509+
hash_ctl.entrysize=sizeof(CFuncHashTabEntry);
510+
hash_ctl.hash=tag_hash;
511+
CFuncHash=hash_create("CFuncHash",
512+
100,
513+
&hash_ctl,
514+
HASH_ELEM |HASH_FUNCTION);
515+
if (CFuncHash==NULL)
516+
ereport(ERROR,
517+
(errcode(ERRCODE_OUT_OF_MEMORY),
518+
errmsg("out of memory")));
519+
}
520+
521+
entry= (CFuncHashTabEntry*)
522+
hash_search(CFuncHash,
523+
&fn_oid,
524+
HASH_ENTER,
525+
&found);
526+
if (entry==NULL)
527+
ereport(ERROR,
528+
(errcode(ERRCODE_OUT_OF_MEMORY),
529+
errmsg("out of memory")));
530+
/* OID is already filled in */
531+
entry->fn_xmin=HeapTupleHeaderGetXmin(procedureTuple->t_data);
532+
entry->fn_cmin=HeapTupleHeaderGetCmin(procedureTuple->t_data);
533+
entry->user_fn=user_fn;
534+
entry->inforec=inforec;
535+
}
536+
537+
/*
538+
* clear_external_function_hash: remove entries for a library being closed
539+
*
540+
* Presently we just zap the entire hash table, but later it might be worth
541+
* the effort to remove only the entries associated with the given handle.
542+
*/
543+
void
544+
clear_external_function_hash(void*filehandle)
545+
{
546+
if (CFuncHash)
547+
hash_destroy(CFuncHash);
548+
CFuncHash=NULL;
549+
}
550+
551+
419552
/*
420553
* Copy an FmgrInfo struct
421554
*

‎src/include/fmgr.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
1212
* Portions Copyright (c) 1994, Regents of the University of California
1313
*
14-
* $PostgreSQL: pgsql/src/include/fmgr.h,v 1.32 2003/11/29 22:40:53 pgsql Exp $
14+
* $PostgreSQL: pgsql/src/include/fmgr.h,v 1.33 2004/01/19 02:06:42 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
@@ -377,6 +377,7 @@ extern Datum OidFunctionCall9(Oid functionId, Datum arg1, Datum arg2,
377377
* Routines in fmgr.c
378378
*/
379379
externPg_finfo_record*fetch_finfo_record(void*filehandle,char*funcname);
380+
externvoidclear_external_function_hash(void*filehandle);
380381
externOidfmgr_internal_function(constchar*proname);
381382
externOidget_fn_expr_rettype(FmgrInfo*flinfo);
382383
externOidget_fn_expr_argtype(FmgrInfo*flinfo,intargnum);

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