bt_search.c File Reference

#include <sys/types.h>
#include <stdio.h>
#include "../include/db.h"
#include "btree.h"

Include dependency graph for bt_search.c:

Go to the source code of this file.

Functions
EPG *	__bt_search (BTREE *t, const DBT *key, int *exactp)
static int	__bt_snext (BTREE *t, PAGE *h, const DBT *key, int *exactp)
static int	__bt_sprev (BTREE *t, PAGE *h, const DBT *key, int *exactp)
static int __bt_snext	__P ((BTREE *, PAGE *, const DBT *, int *))

Function Documentation

__bt_search()

EPG* __bt_search	(	BTREE *	t,
		const DBT *	key,
		int *	exactp
	)

Definition at line 66 of file bt_search.c.

References __bt_cmp(), __bt_snext(), __bt_sprev(), B_NODUPS, BT_CLR, _btree::bt_cur, _btree::bt_mp, BT_PUSH, F_ISSET, _page::flags, GETBINTERNAL, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, _page::nextpg, NULL, P_BLEAF, P_INVALID, P_ROOT, _epg::page, _page::pgno, and _page::prevpg.

Referenced by __bt_bdelete(), __bt_first(), __bt_get(), __bt_put(), and __bt_stkacq().

{
 PAGE *h;
 indx_t base, index, lim;
 pgno_t pg;
 int cmp;

 BT_CLR(t);
 for (pg = P_ROOT;;) {
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (NULL);

 /* Do a binary search on the current page. */
 t->bt_cur.page = h;
 for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) {
 t->bt_cur.index = index = base + (lim >> 1);
 if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) {
 if (h->flags & P_BLEAF) {
 *exactp = 1;
 return (&t->bt_cur);
 }
 goto next;
 }
 if (cmp > 0) {
 base = index + 1;
 --lim;
 }
 }

 /*
 * If it's a leaf page, we're almost done. If no duplicates
 * are allowed, or we have an exact match, we're done. Else,
 * it's possible that there were matching keys on this page,
 * which later deleted, and we're on a page with no matches
 * while there are matches on other pages. If at the start or
 * end of a page, check the adjacent page.
 */
 if (h->flags & P_BLEAF) {
 if (!F_ISSET(t, B_NODUPS)) {
 if (base == 0 &&
 h->prevpg != P_INVALID &&
 __bt_sprev(t, h, key, exactp))
 return (&t->bt_cur);
 if (base == NEXTINDEX(h) &&
 h->nextpg != P_INVALID &&
 __bt_snext(t, h, key, exactp))
 return (&t->bt_cur);
 }
 *exactp = 0;
 t->bt_cur.index = base;
 return (&t->bt_cur);
 }

 /*
 * No match found. Base is the smallest index greater than
 * key and may be zero or a last + 1 index. If it's non-zero,
 * decrement by one, and record the internal page which should
 * be a parent page for the key. If a split later occurs, the
 * inserted page will be to the right of the saved page.
 */
 index = base ? base - 1 : base;

next: BT_PUSH(t, h->pgno, index);
 pg = GETBINTERNAL(h, index)->pgno;
 mpool_put(t->bt_mp, h, 0);
 }
}

__bt_snext()

static int __bt_snext ( BTREE *  t, PAGE *  h, const DBT *  key, int *  exactp  )

static

Definition at line 151 of file bt_search.c.

References __bt_cmp(), _btree::bt_cur, _btree::bt_mp, _epg::index, mpool_get(), mpool_put(), _page::nextpg, NULL, and _epg::page.

Referenced by __bt_search().

{
 EPG e;

 /*
 * Get the next page. The key is either an exact
 * match, or not as good as the one we already have.
 */
 if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
 return (0);
 e.index = 0;
 if (__bt_cmp(t, key, &e) == 0) {
 mpool_put(t->bt_mp, h, 0);
 t->bt_cur = e;
 *exactp = 1;
 return (1);
 }
 mpool_put(t->bt_mp, e.page, 0);
 return (0);
}

__bt_sprev()

static int __bt_sprev ( BTREE *  t, PAGE *  h, const DBT *  key, int *  exactp  )

static

Definition at line 190 of file bt_search.c.

References __bt_cmp(), _btree::bt_cur, _btree::bt_mp, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, NULL, _epg::page, and _page::prevpg.

Referenced by __bt_search().

{
 EPG e;

 /*
 * Get the previous page. The key is either an exact
 * match, or not as good as the one we already have.
 */
 if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
 return (0);
 e.index = NEXTINDEX(e.page) - 1;
 if (__bt_cmp(t, key, &e) == 0) {
 mpool_put(t->bt_mp, h, 0);
 t->bt_cur = e;
 *exactp = 1;
 return (1);
 }
 mpool_put(t->bt_mp, e.page, 0);
 return (0);
}

__P()

static int __bt_sprev __P ( (BTREE *, PAGE *, const DBT *, int *)  )

static