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Commit c3a153a

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tglsfdctglsfdc
committed
Tweak palloc/repalloc to allow zero bytes to be requested, as per recent
proposal. Eliminate several dozen now-unnecessary hacks to avoid palloc(0). (It's likely there are more that I didn't find.)
1 parent 24a1e20 commit c3a153a

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19 files changed

+113
-113
lines changed

19 files changed

+113
-113
lines changed

‎src/backend/access/nbtree/nbtree.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1994, Regents of the University of California
1313
*
1414
* IDENTIFICATION
15-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.117 2004/06/02 17:28:17 tgl Exp $
15+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.118 2004/06/05 19:48:07 tgl Exp $
1616
*
1717
*-------------------------------------------------------------------------
1818
*/
@@ -693,7 +693,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
693693
/* No point in remembering more than MaxFSMPages pages */
694694
maxFreePages = MaxFSMPages;
695695
if ((BlockNumber) maxFreePages > num_pages)
696-
maxFreePages = (int) num_pages + 1; /* +1 to avoid palloc(0) */
696+
maxFreePages = (int) num_pages;
697697
freePages = (BlockNumber *) palloc(maxFreePages * sizeof(BlockNumber));
698698
nFreePages = 0;
699699

‎src/backend/commands/analyze.c

Lines changed: 5 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.73 2004/05/26 04:41:09 neilc Exp $
11+
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.74 2004/06/05 19:48:07 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -226,9 +226,8 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
226226
else
227227
{
228228
attr_cnt = onerel->rd_att->natts;
229-
/* +1 here is just to avoid palloc(0) with zero-column table */
230-
vacattrstats = (VacAttrStats **) palloc((attr_cnt + 1) *
231-
sizeof(VacAttrStats *));
229+
vacattrstats = (VacAttrStats **)
230+
palloc(attr_cnt * sizeof(VacAttrStats *));
232231
tcnt = 0;
233232
for (i = 1; i <= attr_cnt; i++)
234233
{
@@ -505,8 +504,8 @@ compute_index_stats(Relation onerel, double totalrows,
505504
estate);
506505

507506
/* Compute and save index expression values */
508-
exprvals = (Datum *) palloc((numrows * attr_cnt + 1) * sizeof(Datum));
509-
exprnulls = (bool *) palloc((numrows * attr_cnt + 1) * sizeof(bool));
507+
exprvals = (Datum *) palloc(numrows * attr_cnt * sizeof(Datum));
508+
exprnulls = (bool *) palloc(numrows * attr_cnt * sizeof(bool));
510509
numindexrows = 0;
511510
tcnt = 0;
512511
for (rowno = 0; rowno < numrows; rowno++)

‎src/backend/commands/copy.c

Lines changed: 13 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.224 2004/05/26 04:41:10 neilc Exp $
11+
* $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.225 2004/06/05 19:48:07 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1158,13 +1158,11 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
11581158

11591159
/*
11601160
* Get info about the columns we need to process.
1161-
*
1162-
* +1's here are to avoid palloc(0) in a zero-column table.
11631161
*/
1164-
out_functions = (FmgrInfo *) palloc((num_phys_attrs + 1) * sizeof(FmgrInfo));
1165-
elements = (Oid *) palloc((num_phys_attrs + 1) * sizeof(Oid));
1166-
isvarlena = (bool *) palloc((num_phys_attrs + 1) * sizeof(bool));
1167-
force_quote = (bool *) palloc((num_phys_attrs + 1) * sizeof(bool));
1162+
out_functions = (FmgrInfo *) palloc(num_phys_attrs * sizeof(FmgrInfo));
1163+
elements = (Oid *) palloc(num_phys_attrs * sizeof(Oid));
1164+
isvarlena = (bool *) palloc(num_phys_attrs * sizeof(bool));
1165+
force_quote = (bool *) palloc(num_phys_attrs * sizeof(bool));
11681166
foreach(cur, attnumlist)
11691167
{
11701168
int attnum = lfirst_int(cur);
@@ -1501,14 +1499,13 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
15011499
* relation, including the input function, the element type (to pass
15021500
* to the input function), and info about defaults and constraints.
15031501
* (Which input function we use depends on text/binary format choice.)
1504-
* +1's here are to avoid palloc(0) in a zero-column table.
15051502
*/
1506-
in_functions = (FmgrInfo *) palloc((num_phys_attrs + 1) * sizeof(FmgrInfo));
1507-
elements = (Oid *) palloc((num_phys_attrs + 1) * sizeof(Oid));
1508-
defmap = (int *) palloc((num_phys_attrs + 1) * sizeof(int));
1509-
defexprs = (ExprState **) palloc((num_phys_attrs + 1) * sizeof(ExprState *));
1510-
constraintexprs = (ExprState **) palloc0((num_phys_attrs + 1) * sizeof(ExprState *));
1511-
force_notnull = (bool *) palloc((num_phys_attrs + 1) * sizeof(bool));
1503+
in_functions = (FmgrInfo *) palloc(num_phys_attrs * sizeof(FmgrInfo));
1504+
elements = (Oid *) palloc(num_phys_attrs * sizeof(Oid));
1505+
defmap = (int *) palloc(num_phys_attrs * sizeof(int));
1506+
defexprs = (ExprState **) palloc(num_phys_attrs * sizeof(ExprState *));
1507+
constraintexprs = (ExprState **) palloc0(num_phys_attrs * sizeof(ExprState *));
1508+
force_notnull = (bool *) palloc(num_phys_attrs * sizeof(bool));
15121509

15131510
for (attnum = 1; attnum <= num_phys_attrs; attnum++)
15141511
{
@@ -1635,8 +1632,8 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
16351632
fmgr_info(in_func_oid, &oid_in_function);
16361633
}
16371634

1638-
values = (Datum *) palloc((num_phys_attrs + 1) * sizeof(Datum));
1639-
nulls = (char *) palloc((num_phys_attrs + 1) * sizeof(char));
1635+
values = (Datum *) palloc(num_phys_attrs * sizeof(Datum));
1636+
nulls = (char *) palloc(num_phys_attrs * sizeof(char));
16401637

16411638
/* Make room for a PARAM_EXEC value for domain constraint checks */
16421639
if (hasConstraints)

‎src/backend/commands/tablecmds.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.110 2004/06/04 20:35:21 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.111 2004/06/05 19:48:07 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -727,10 +727,10 @@ MergeAttributes(List *schema, List *supers, bool istemp,
727727
* newattno[] will contain the child-table attribute numbers for
728728
* the attributes of this parent table. (They are not the same
729729
* for parents after the first one, nor if we have dropped
730-
* columns.) +1 is to prevent error if parent has zero columns.
730+
* columns.)
731731
*/
732732
newattno = (AttrNumber *)
733-
palloc((tupleDesc->natts + 1) * sizeof(AttrNumber));
733+
palloc(tupleDesc->natts * sizeof(AttrNumber));
734734

735735
for (parent_attno = 1; parent_attno <= tupleDesc->natts;
736736
parent_attno++)

‎src/backend/commands/vacuum.c

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
*
1414
*
1515
* IDENTIFICATION
16-
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.279 2004/05/31 19:24:05 tgl Exp $
16+
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.280 2004/06/05 19:48:07 tgl Exp $
1717
*
1818
*-------------------------------------------------------------------------
1919
*/
@@ -2883,9 +2883,8 @@ vac_update_fsm(Relation onerel, VacPageList fraged_pages,
28832883
*/
28842884
threshold = GetAvgFSMRequestSize(&onerel->rd_node);
28852885

2886-
/* +1 to avoid palloc(0) */
28872886
pageSpaces = (PageFreeSpaceInfo *)
2888-
palloc((nPages + 1) * sizeof(PageFreeSpaceInfo));
2887+
palloc(nPages * sizeof(PageFreeSpaceInfo));
28892888
outPages = 0;
28902889

28912890
for (i = 0; i < nPages; i++)

‎src/backend/commands/vacuumlazy.c

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -31,7 +31,7 @@
3131
*
3232
*
3333
* IDENTIFICATION
34-
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.41 2004/05/31 19:24:05 tgl Exp $
34+
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.42 2004/06/05 19:48:07 tgl Exp $
3535
*
3636
*-------------------------------------------------------------------------
3737
*/
@@ -918,9 +918,6 @@ lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
918918
/* No need to allocate more pages than the relation has blocks */
919919
if (relblocks < (BlockNumber) maxpages)
920920
maxpages = (int) relblocks;
921-
/* avoid palloc(0) */
922-
if (maxpages < 1)
923-
maxpages = 1;
924921

925922
vacrelstats->fs_is_heap = false;
926923
vacrelstats->num_free_pages = 0;

‎src/backend/executor/execQual.c

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.162 2004/06/01 03:28:41 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.163 2004/06/05 19:48:08 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2129,8 +2129,6 @@ ExecEvalRow(RowExprState *rstate,
21292129

21302130
/* Allocate workspace */
21312131
nargs = list_length(rstate->args);
2132-
if (nargs == 0) /* avoid palloc(0) if no fields */
2133-
nargs = 1;
21342132
values = (Datum *) palloc(nargs * sizeof(Datum));
21352133
nulls = (char *) palloc(nargs * sizeof(char));
21362134

‎src/backend/optimizer/prep/prepunion.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*
1515
*
1616
* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.113 2004/06/05 01:55:04 tgl Exp $
17+
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.114 2004/06/05 19:48:08 tgl Exp $
1818
*
1919
*-------------------------------------------------------------------------
2020
*/
@@ -538,9 +538,9 @@ generate_append_tlist(List *colTypes, bool flag,
538538
* First extract typmods to use.
539539
*
540540
* If the inputs all agree on type and typmod of a particular column, use
541-
* that typmod; else use -1. (+1 here in case of zero columns.)
541+
* that typmod; else use -1.
542542
*/
543-
colTypmods = (int32 *) palloc(list_length(colTypes) * sizeof(int32) + 1);
543+
colTypmods = (int32 *) palloc(list_length(colTypes) * sizeof(int32));
544544

545545
foreach(planl, input_plans)
546546
{

‎src/backend/optimizer/util/clauses.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.173 2004/06/01 04:47:45 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.174 2004/06/05 19:48:08 tgl Exp $
1212
*
1313
* HISTORY
1414
* AUTHOR DATE MAJOR EVENT
@@ -2016,7 +2016,7 @@ inline_function(Oid funcid, Oid result_type, List *args,
20162016
* actual substitution of the inputs. So start building expression
20172017
* with inputs substituted.
20182018
*/
2019-
usecounts = (int *) palloc0((funcform->pronargs + 1) * sizeof(int));
2019+
usecounts = (int *) palloc0(funcform->pronargs * sizeof(int));
20202020
newexpr = substitute_actual_parameters(newexpr, funcform->pronargs,
20212021
args, usecounts);
20222022

‎src/backend/storage/freespace/freespace.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.30 2004/01/26 22:35:32 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.31 2004/06/05 19:48:08 tgl Exp $
1212
*
1313
*
1414
* NOTES:
@@ -893,7 +893,7 @@ LoadFreeSpaceMap(void)
893893
len = nPages * sizeof(IndexFSMPageData);
894894
else
895895
len = nPages * sizeof(FSMPageData);
896-
data = (char *) palloc(len + 1); /* +1 to avoid palloc(0) */
896+
data = (char *) palloc(len);
897897
if (fread(data, 1, len, fp) != len)
898898
{
899899
elog(LOG, "premature EOF in \"%s\"", cachefilename);

‎src/backend/storage/lmgr/deadlock.c

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
*
1313
*
1414
* IDENTIFICATION
15-
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.27 2003/12/01 21:59:25 momjian Exp $
15+
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.28 2004/06/05 19:48:08 tgl Exp $
1616
*
1717
* Interface:
1818
*
@@ -147,11 +147,10 @@ InitDeadLockChecking(void)
147147
* We need to consider rearranging at most MaxBackends/2 wait queues
148148
* (since it takes at least two waiters in a queue to create a soft
149149
* edge), and the expanded form of the wait queues can't involve more
150-
* than MaxBackends total waiters. (But avoid palloc(0) if
151-
* MaxBackends = 1.)
150+
* than MaxBackends total waiters.
152151
*/
153152
waitOrders = (WAIT_ORDER *)
154-
palloc(((MaxBackends + 1) / 2) * sizeof(WAIT_ORDER));
153+
palloc((MaxBackends / 2) * sizeof(WAIT_ORDER));
155154
waitOrderProcs = (PGPROC **) palloc(MaxBackends * sizeof(PGPROC *));
156155

157156
/*

‎src/backend/storage/lmgr/lock.c

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.132 2004/05/28 05:13:05 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.133 2004/06/05 19:48:08 tgl Exp $
1212
*
1313
* NOTES
1414
* Outside modules can create a lock table and acquire/release
@@ -1361,9 +1361,6 @@ GetLockStatusData(void)
13611361

13621362
data->nelements = i = proclockTable->hctl->nentries;
13631363

1364-
if (i == 0)
1365-
i = 1; /* avoid palloc(0) if empty table */
1366-
13671364
data->proclockaddrs = (SHMEM_OFFSET *) palloc(sizeof(SHMEM_OFFSET) * i);
13681365
data->proclocks = (PROCLOCK *) palloc(sizeof(PROCLOCK) * i);
13691366
data->procs = (PGPROC *) palloc(sizeof(PGPROC) * i);

‎src/backend/tcop/pquery.c

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.79 2004/05/26 18:54:08 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.80 2004/06/05 19:48:08 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -347,10 +347,9 @@ PortalSetResultFormat(Portal portal, int nFormats, int16 *formats)
347347
if (portal->tupDesc == NULL)
348348
return;
349349
natts = portal->tupDesc->natts;
350-
/* +1 avoids palloc(0) if no columns */
351350
portal->formats = (int16 *)
352351
MemoryContextAlloc(PortalGetHeapMemory(portal),
353-
(natts + 1) * sizeof(int16));
352+
natts * sizeof(int16));
354353
if (nFormats > 1)
355354
{
356355
/* format specified for each column */

‎src/backend/utils/adt/name.c

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*
1515
*
1616
* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/utils/adt/name.c,v 1.52 2004/05/30 23:40:35 neilc Exp $
17+
* $PostgreSQL: pgsql/src/backend/utils/adt/name.c,v 1.53 2004/06/05 19:48:09 tgl Exp $
1818
*
1919
*-------------------------------------------------------------------------
2020
*/
@@ -358,9 +358,7 @@ current_schemas(PG_FUNCTION_ARGS)
358358
int i;
359359
ArrayType *array;
360360

361-
/* +1 here is just to avoid palloc(0) error */
362-
363-
names = (Datum *) palloc((list_length(search_path) + 1) * sizeof(Datum));
361+
names = (Datum *) palloc(list_length(search_path) * sizeof(Datum));
364362
i = 0;
365363
foreach(l, search_path)
366364
{

‎src/backend/utils/mmgr/README

Lines changed: 21 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
$PostgreSQL: pgsql/src/backend/utils/mmgr/README,v 1.5 2003/11/29 19:52:04 pgsql Exp $
1+
$PostgreSQL: pgsql/src/backend/utils/mmgr/README,v 1.6 2004/06/05 19:48:09 tgl Exp $
22

33
Notes about memory allocation redesign
44
--------------------------------------
@@ -53,6 +53,26 @@ that can be reset or deleted at strategic times within a query, such as
5353
after each tuple.
5454

5555

56+
Some notes about the palloc API versus standard C library
57+
---------------------------------------------------------
58+
59+
The behavior of palloc and friends is similar to the standard C library's
60+
malloc and friends, but there are some deliberate differences too. Here
61+
are some notes to clarify the behavior.
62+
63+
* If out of memory, palloc and repalloc exit via elog(ERROR). They never
64+
return NULL, and it is not necessary or useful to test for such a result.
65+
66+
* palloc(0) is explicitly a valid operation. It does not return a NULL
67+
pointer, but a valid chunk of which no bytes may be used. (However, the
68+
chunk might later be repalloc'd larger; it can also be pfree'd without
69+
error.) (Note: this behavior is new in Postgres 7.5; earlier versions
70+
disallowed palloc(0). It seems more consistent to allow it, however.)
71+
Similarly, repalloc allows realloc'ing to zero size.
72+
73+
* pfree and repalloc do not accept a NULL pointer. This is intentional.
74+
75+
5676
pfree/repalloc no longer depend on CurrentMemoryContext
5777
-------------------------------------------------------
5878

‎src/backend/utils/mmgr/mcxt.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*
1515
*
1616
* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/utils/mmgr/mcxt.c,v 1.44 2003/11/29 19:52:04 pgsql Exp $
17+
* $PostgreSQL: pgsql/src/backend/utils/mmgr/mcxt.c,v 1.45 2004/06/05 19:48:09 tgl Exp $
1818
*
1919
*-------------------------------------------------------------------------
2020
*/
@@ -565,7 +565,7 @@ pfree(void *pointer)
565565

566566
/*
567567
* repalloc
568-
*
568+
* Adjust the size of a previously allocated chunk.
569569
*/
570570
void *
571571
repalloc(void *pointer, Size size)

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