bt_seq.c File Reference

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

Include dependency graph for bt_seq.c:

Go to the source code of this file.

Functions
static int	__bt_first (BTREE *t, const DBT *key, EPG *erval, int *exactp)
int	__bt_seq (DB *dbp, DBT *key, DBT *data, u_int flags) const
static int	__bt_seqadv (BTREE *t, EPG *ep, int flags)
static int	__bt_seqset (BTREE *t, EPG *ep, DBT *key, int flags)
void	__bt_setcur (BTREE *t, pgno_t pgno, u_int index)
static int __bt_first	__P ((BTREE *, const DBT *, EPG *, int *))
static int __bt_seqadv	__P ((BTREE *, EPG *, int))
static int __bt_seqset	__P ((BTREE *, EPG *, DBT *, int))

Function Documentation

__bt_first()

static int __bt_first ( BTREE *  t, const DBT *  key, EPG *  erval, int *  exactp  )

static

Definition at line 342 of file bt_seq.c.

References __bt_cmp(), __bt_search(), B_NODUPS, _btree::bt_mp, F_ISSET, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, _page::nextpg, NULL, P_INVALID, _epg::page, _page::pgno, _page::prevpg, RET_ERROR, RET_SPECIAL, and RET_SUCCESS.

Referenced by __bt_seqadv(), and __bt_seqset().

{
 PAGE *h;
 EPG *ep, save;
 pgno_t pg;

 /*
 * Find any matching record; __bt_search pins the page.
 *
 * If it's an exact match and duplicates are possible, walk backwards
 * in the tree until we find the first one. Otherwise, make sure it's
 * a valid key (__bt_search may return an index just past the end of a
 * page) and return it.
 */
 if ((ep = __bt_search(t, key, exactp)) == NULL)
 return (RET_SPECIAL);
 if (*exactp) {
 if (F_ISSET(t, B_NODUPS)) {
 *erval = *ep;
 return (RET_SUCCESS);
 }

 /*
 * Walk backwards, as long as the entry matches and there are
 * keys left in the tree. Save a copy of each match in case
 * we go too far.
 */
 save = *ep;
 h = ep->page;
 do {
 if (save.page->pgno != ep->page->pgno) {
 mpool_put(t->bt_mp, save.page, 0);
 save = *ep;
 } else
 save.index = ep->index;

 /*
 * Don't unpin the page the last (or original) match
 * was on, but make sure it's unpinned if an error
 * occurs.
 */
 if (ep->index == 0) {
 if (h->prevpg == P_INVALID)
 break;
 if (h->pgno != save.page->pgno)
 mpool_put(t->bt_mp, h, 0);
 if ((h = mpool_get(t->bt_mp,
 h->prevpg, 0)) == NULL) {
 if (h->pgno == save.page->pgno)
 mpool_put(t->bt_mp,
 save.page, 0);
 return (RET_ERROR);
 }
 ep->page = h;
 ep->index = NEXTINDEX(h);
 }
 --ep->index;
 } while (__bt_cmp(t, key, ep) == 0);

 /*
 * Reach here with the last page that was looked at pinned,
 * which may or may not be the same as the last (or original)
 * match page. If it's not useful, release it.
 */
 if (h->pgno != save.page->pgno)
 mpool_put(t->bt_mp, h, 0);

 *erval = save;
 return (RET_SUCCESS);
 }

 /* If at the end of a page, find the next entry. */
 if (ep->index == NEXTINDEX(ep->page)) {
 h = ep->page;
 pg = h->nextpg;
 mpool_put(t->bt_mp, h, 0);
 if (pg == P_INVALID)
 return (RET_SPECIAL);
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (RET_ERROR);
 ep->index = 0;
 ep->page = h;
 }
 *erval = *ep;
 return (RET_SUCCESS);
}

__bt_seq()

int __bt_seq	(	DB *	dbp,
		DBT *	key,
		DBT *	data,
		u_int	flags
	)		const

Definition at line 77 of file bt_seq.c.

References __bt_ret(), __bt_seqadv(), __bt_seqset(), __bt_setcur(), B_DB_LOCK, _btree::bt_cursor, _btree::bt_mp, _btree::bt_pinned, _btree::bt_rdata, _btree::bt_rkey, CURS_INIT, errno, F_ISSET, _epg::index, __db::internal, mpool_put(), NULL, _epg::page, _page::pgno, R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV, RET_ERROR, RET_SUCCESS, and status.

Referenced by __bt_open().

{
 BTREE *t;
 EPG e;
 int status;

 t = dbp->internal;

 /* Toss any page pinned across calls. */
 if (t->bt_pinned != NULL) {
 mpool_put(t->bt_mp, t->bt_pinned, 0);
 t->bt_pinned = NULL;
 }

 /*
 * If scan uninitialized as yet, or starting at a specific record, set
 * the scan to a specific key. Both __bt_seqset and __bt_seqadv pin
 * the page the cursor references if they're successful.
 */
 switch (flags) {
 case R_NEXT:
 case R_PREV:
 if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
 status = __bt_seqadv(t, &e, flags);
 break;
 }
 /* FALLTHROUGH */
 case R_FIRST:
 case R_LAST:
 case R_CURSOR:
 status = __bt_seqset(t, &e, key, flags);
 break;
 default:
 errno = EINVAL;
 return (RET_ERROR);
 }

 if (status == RET_SUCCESS) {
 __bt_setcur(t, e.page->pgno, e.index);

 status =
 __bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0);

 /*
 * If the user is doing concurrent access, we copied the
 * key/data, toss the page.
 */
 if (F_ISSET(t, B_DB_LOCK))
 mpool_put(t->bt_mp, e.page, 0);
 else
 t->bt_pinned = e.page;
 }
 return (status);
}

__bt_seqadv()

static int __bt_seqadv ( BTREE *  t, EPG *  ep, int  flags  )

static

Definition at line 240 of file bt_seq.c.

References __bt_first(), _btree::bt_cursor, _btree::bt_mp, c, CURS_ACQUIRE, CURS_AFTER, CURS_BEFORE, F_CLR, F_ISSET, _epgno::index, _epg::index, _cursor::key, mpool_get(), mpool_put(), NEXTINDEX, _page::nextpg, NULL, P_INVALID, _epg::page, _cursor::pg, _epgno::pgno, _page::prevpg, R_NEXT, R_PREV, RET_ERROR, RET_SPECIAL, and RET_SUCCESS.

Referenced by __bt_seq().

{
 CURSOR *c;
 PAGE *h;
 indx_t index = 0;
 pgno_t pg;
 int exact;

 /*
 * There are a couple of states that we can be in. The cursor has
 * been initialized by the time we get here, but that's all we know.
 */
 c = &t->bt_cursor;

 /*
 * The cursor was deleted where there weren't any duplicate records,
 * so the key was saved. Find out where that key would go in the
 * current tree. It doesn't matter if the returned key is an exact
 * match or not -- if it's an exact match, the record was added after
 * the delete so we can just return it. If not, as long as there's
 * a record there, return it.
 */
 if (F_ISSET(c, CURS_ACQUIRE))
 return (__bt_first(t, &c->key, ep, &exact));

 /* Get the page referenced by the cursor. */
 if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
 return (RET_ERROR);

 /*
 * Find the next/previous record in the tree and point the cursor at
 * it. The cursor may not be moved until a new key has been found.
 */
 switch (flags) {
 case R_NEXT: /* Next record. */
 /*
 * The cursor was deleted in duplicate records, and moved
 * forward to a record that has yet to be returned. Clear
 * that flag, and return the record.
 */
 if (F_ISSET(c, CURS_AFTER))
 goto usecurrent;
 index = c->pg.index;
 if (++index == NEXTINDEX(h)) {
 pg = h->nextpg;
 mpool_put(t->bt_mp, h, 0);
 if (pg == P_INVALID)
 return (RET_SPECIAL);
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (RET_ERROR);
 index = 0;
 }
 break;
 case R_PREV: /* Previous record. */
 /*
 * The cursor was deleted in duplicate records, and moved
 * backward to a record that has yet to be returned. Clear
 * that flag, and return the record.
 */
 if (F_ISSET(c, CURS_BEFORE)) {
usecurrent: F_CLR(c, CURS_AFTER | CURS_BEFORE);
 ep->page = h;
 ep->index = c->pg.index;
 return (RET_SUCCESS);
 }
 index = c->pg.index;
 if (index == 0) {
 pg = h->prevpg;
 mpool_put(t->bt_mp, h, 0);
 if (pg == P_INVALID)
 return (RET_SPECIAL);
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (RET_ERROR);
 index = NEXTINDEX(h) - 1;
 } else
 --index;
 break;
 }

 ep->page = h;
 ep->index = index;
 return (RET_SUCCESS);
}

__bt_seqset()

static int __bt_seqset ( BTREE *  t, EPG *  ep, DBT *  key, int  flags  )

static

Definition at line 152 of file bt_seq.c.

References __bt_first(), _btree::bt_mp, DBT::data, errno, _page::flags, GETBINTERNAL, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, NULL, P_BLEAF, P_RLEAF, P_ROOT, _epg::page, R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV, RET_ERROR, RET_SPECIAL, RET_SUCCESS, and DBT::size.

Referenced by __bt_seq().

{
 PAGE *h;
 pgno_t pg;
 int exact;

 /*
 * Find the first, last or specific key in the tree and point the
 * cursor at it. The cursor may not be moved until a new key has
 * been found.
 */
 switch (flags) {
 case R_CURSOR: /* Keyed scan. */
 /*
 * Find the first instance of the key or the smallest key
 * which is greater than or equal to the specified key.
 */
 if (key->data == NULL || key->size == 0) {
 errno = EINVAL;
 return (RET_ERROR);
 }
 return (__bt_first(t, key, ep, &exact));
 case R_FIRST: /* First record. */
 case R_NEXT:
 /* Walk down the left-hand side of the tree. */
 for (pg = P_ROOT;;) {
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (RET_ERROR);

 /* Check for an empty tree. */
 if (NEXTINDEX(h) == 0) {
 mpool_put(t->bt_mp, h, 0);
 return (RET_SPECIAL);
 }

 if (h->flags & (P_BLEAF | P_RLEAF))
 break;
 pg = GETBINTERNAL(h, 0)->pgno;
 mpool_put(t->bt_mp, h, 0);
 }
 ep->page = h;
 ep->index = 0;
 break;
 case R_LAST: /* Last record. */
 case R_PREV:
 /* Walk down the right-hand side of the tree. */
 for (pg = P_ROOT;;) {
 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 return (RET_ERROR);

 /* Check for an empty tree. */
 if (NEXTINDEX(h) == 0) {
 mpool_put(t->bt_mp, h, 0);
 return (RET_SPECIAL);
 }

 if (h->flags & (P_BLEAF | P_RLEAF))
 break;
 pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
 mpool_put(t->bt_mp, h, 0);
 }

 ep->page = h;
 ep->index = NEXTINDEX(h) - 1;
 break;
 }
 return (RET_SUCCESS);
}

__bt_setcur()

void __bt_setcur	(	BTREE *	t,
		pgno_t	pgno,
		u_int	index
	)

Definition at line 443 of file bt_seq.c.

References _btree::bt_cursor, CURS_ACQUIRE, CURS_AFTER, CURS_BEFORE, CURS_INIT, DBT::data, F_CLR, F_SET, free(), _epgno::index, _cursor::key, NULL, _cursor::pg, _epgno::pgno, and DBT::size.

Referenced by __bt_put(), and __bt_seq().

{
 /* Lose any already deleted key. */
 if (t->bt_cursor.key.data != NULL) {
 free(t->bt_cursor.key.data);
 t->bt_cursor.key.size = 0;
 t->bt_cursor.key.data = NULL;
 }
 F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);

 /* Update the cursor. */
 t->bt_cursor.pg.pgno = pgno;
 t->bt_cursor.pg.index = index;
 F_SET(&t->bt_cursor, CURS_INIT);
}

__P() [1/3]

static int __bt_first __P ( (BTREE *, const DBT *, EPG *, int *)  )

static

__P() [2/3]

static int __bt_seqadv __P ( (BTREE *, EPG *, int)  )

static

__P() [3/3]

static int __bt_seqset __P ( (BTREE *, EPG *, DBT *, int)  )

static