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Avoid allocations in critical sections.

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If a palloc in a critical section fails, it becomes a PANIC.
This commit is contained in:
Heikki Linnakangas 2014-04-04 13:12:38 +03:00
parent 0de9963b0b
commit af7004ed6c
3 changed files with 43 additions and 43 deletions
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55
src/backend/access/nbtree/nbtinsert.c
View File

@ -1828,8 +1828,10 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
BTPageOpaque rootopaque;
ItemId itemid;
IndexTuple item;
Size itemsz;
IndexTuple new_item;
IndexTuple left_item;
Size left_item_sz;
IndexTuple right_item;
Size right_item_sz;
Buffer metabuf;
Page metapg;
BTMetaPageData *metad;
@ -1848,6 +1850,26 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
metapg = BufferGetPage(metabuf);
metad = BTPageGetMeta(metapg);
/*
* Create downlink item for left page (old root). Since this will be the
* first item in a non-leaf page, it implicitly has minus-infinity key
* value, so we need not store any actual key in it.
*/
left_item_sz = sizeof(IndexTupleData);
left_item = (IndexTuple) palloc(left_item_sz);
left_item->t_info = left_item_sz;
ItemPointerSet(&(left_item->t_tid), lbkno, P_HIKEY);
/*
* Create downlink item for right page. The key for it is obtained from
* the "high key" position in the left page.
*/
itemid = PageGetItemId(lpage, P_HIKEY);
right_item_sz = ItemIdGetLength(itemid);
item = (IndexTuple) PageGetItem(lpage, itemid);
right_item = CopyIndexTuple(item);
ItemPointerSet(&(right_item->t_tid), rbkno, P_HIKEY);
/* NO EREPORT(ERROR) from here till newroot op is logged */
START_CRIT_SECTION();
@ -1865,16 +1887,6 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
metad->btm_fastroot = rootblknum;
metad->btm_fastlevel = rootopaque->btpo.level;
/*
* Create downlink item for left page (old root). Since this will be the
* first item in a non-leaf page, it implicitly has minus-infinity key
* value, so we need not store any actual key in it.
*/
itemsz = sizeof(IndexTupleData);
new_item = (IndexTuple) palloc(itemsz);
new_item->t_info = itemsz;
ItemPointerSet(&(new_item->t_tid), lbkno, P_HIKEY);
/*
* Insert the left page pointer into the new root page. The root page is
* the rightmost page on its level so there is no "high key" in it; the
@ -1883,32 +1895,20 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
* Note: we *must* insert the two items in item-number order, for the
* benefit of _bt_restore_page().
*/
if (PageAddItem(rootpage, (Item) new_item, itemsz, P_HIKEY,
if (PageAddItem(rootpage, (Item) left_item, left_item_sz, P_HIKEY,
false, false) == InvalidOffsetNumber)
elog(PANIC, "failed to add leftkey to new root page"
" while splitting block %u of index \"%s\"",
BufferGetBlockNumber(lbuf), RelationGetRelationName(rel));
pfree(new_item);
/*
* Create downlink item for right page. The key for it is obtained from
* the "high key" position in the left page.
*/
itemid = PageGetItemId(lpage, P_HIKEY);
itemsz = ItemIdGetLength(itemid);
item = (IndexTuple) PageGetItem(lpage, itemid);
new_item = CopyIndexTuple(item);
ItemPointerSet(&(new_item->t_tid), rbkno, P_HIKEY);
/*
* insert the right page pointer into the new root page.
*/
if (PageAddItem(rootpage, (Item) new_item, itemsz, P_FIRSTKEY,
if (PageAddItem(rootpage, (Item) right_item, right_item_sz, P_FIRSTKEY,
false, false) == InvalidOffsetNumber)
elog(PANIC, "failed to add rightkey to new root page"
" while splitting block %u of index \"%s\"",
BufferGetBlockNumber(lbuf), RelationGetRelationName(rel));
pfree(new_item);
MarkBufferDirty(rootbuf);
MarkBufferDirty(metabuf);
@ -1956,6 +1956,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
/* done with metapage */
_bt_relbuf(rel, metabuf);
pfree(left_item);
pfree(right_item);
return rootbuf;
}

10
src/backend/access/transam/xlog.c
View File

@ -2289,6 +2289,7 @@ XLogFileInit(uint32 log, uint32 seg,
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
char zbuffer_raw[BLCKSZ + MAXIMUM_ALIGNOF];
char *zbuffer;
uint32 installed_log;
uint32 installed_seg;
@ -2346,11 +2347,11 @@ XLogFileInit(uint32 log, uint32 seg,
* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
* log file.
*
* Note: palloc zbuffer, instead of just using a local char array, to
* ensure it is reasonably well-aligned; this may save a few cycles
* transferring data to the kernel.
* Note: ensure the buffer is reasonably well-aligned; this may save a few
* cycles transferring data to the kernel.
*/
zbuffer = (char *) palloc0(XLOG_BLCKSZ);
zbuffer = (char *) MAXALIGN(zbuffer_raw);
memset(zbuffer, 0, BLCKSZ);
for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ)
{
errno = 0;
@ -2370,7 +2371,6 @@ XLogFileInit(uint32 log, uint32 seg,
errmsg("could not write to file \"%s\": %m", tmppath)));
}
}
pfree(zbuffer);
if (pg_fsync(fd) != 0)
ereport(ERROR,

21
src/backend/storage/page/bufpage.c
View File

@ -15,6 +15,7 @@
#include "postgres.h"
#include "access/htup.h"
#include "access/itup.h"
#include "storage/bufpage.h"
@ -363,8 +364,6 @@ PageRepairFragmentation(Page page)
Offset pd_lower = ((PageHeader) page)->pd_lower;
Offset pd_upper = ((PageHeader) page)->pd_upper;
Offset pd_special = ((PageHeader) page)->pd_special;
itemIdSort itemidbase,
itemidptr;
ItemId lp;
int nline,
nstorage,
@ -414,10 +413,11 @@ PageRepairFragmentation(Page page)
((PageHeader) page)->pd_upper = pd_special;
}
else
{ /* nstorage != 0 */
{
/* Need to compact the page the hard way */
itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nstorage);
itemidptr = itemidbase;
itemIdSortData itemidbase[MaxHeapTuplesPerPage];
itemIdSort itemidptr = itemidbase;
totallen = 0;
for (i = 0; i < nline; i++)
{
@ -462,8 +462,6 @@ PageRepairFragmentation(Page page)
}
((PageHeader) page)->pd_upper = upper;
pfree(itemidbase);
}
/* Set hint bit for PageAddItem */
@ -712,8 +710,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
Offset pd_lower = phdr->pd_lower;
Offset pd_upper = phdr->pd_upper;
Offset pd_special = phdr->pd_special;
itemIdSort itemidbase,
itemidptr;
itemIdSortData itemidbase[MaxIndexTuplesPerPage];
itemIdSort itemidptr;
ItemId lp;
int nline,
nused;
@ -725,6 +723,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
int nextitm;
OffsetNumber offnum;
Assert(nitems < MaxIndexTuplesPerPage);
/*
* If there aren't very many items to delete, then retail
* PageIndexTupleDelete is the best way. Delete the items in reverse
@ -759,7 +759,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
* still validity-checking.
*/
nline = PageGetMaxOffsetNumber(page);
itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nline);
itemidptr = itemidbase;
totallen = 0;
nused = 0;
@ -825,6 +824,4 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData);
phdr->pd_upper = upper;
pfree(itemidbase);
}