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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 6c1cfbacb9
commit 7d1e0e8d7a
4 changed files with 46 additions and 48 deletions
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55
src/backend/access/nbtree/nbtinsert.c
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@ -1839,8 +1839,10 @@ _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;
@ -1859,6 +1861,26 @@ _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();
@ -1876,16 +1898,6 @@ _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
@ -1894,32 +1906,20 @@ _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);
@ -1967,6 +1967,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
/* done with metapage */
_bt_relbuf(rel, metabuf);
pfree(left_item);
pfree(right_item);
return rootbuf;
}