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.

{
    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);
    }
}

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().

__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.

{
    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);
}

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().

__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.

{
    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);
}

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().

__P()

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

static