bt_put.c

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/*-
 * Copyright (c) 1990, 1993, 1994
 * The Regents of the University of California. All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 * This product includes software developed by the University of
 * California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_put.c 8.8 (Berkeley) 7/26/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../include/db.h"
#include "btree.h"

static EPG *bt_fast __P((BTREE *, const DBT *, const DBT *, int *));

/*
 * __BT_PUT -- Add a btree item to the tree.
 *
 * Parameters:
 * dbp: pointer to access method
 * key: key
 * data: data
 * flag: R_NOOVERWRITE
 *
 * Returns:
 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key is already in the
 * tree and R_NOOVERWRITE specified.
 */
int
__bt_put(dbp, key, data, flags)
 const DB *dbp;
 DBT *key;
 const DBT *data;
 u_int flags;
{
 BTREE *t;
 DBT tkey, tdata;
 EPG *e = 0;
 PAGE *h;
 indx_t idx, nxtindex;
 pgno_t pg;
 u_int32_t nbytes;
 int dflags, exact, status;
 char *dest, db[NOVFLSIZE], kb[NOVFLSIZE];

 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;
 }

 /* Check for change to a read-only tree. */
 if (F_ISSET(t, B_RDONLY)) {
 errno = EPERM;
 return (RET_ERROR);
 }

 switch (flags) {
 case 0:
 case R_NOOVERWRITE:
 break;
 case R_CURSOR:
 /*
 * If flags is R_CURSOR, put the cursor. Must already
 * have started a scan and not have already deleted it.
 */
 if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
 !F_ISSET(&t->bt_cursor,
 CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
 break;
 /* FALLTHROUGH */
 default:
 errno = EINVAL;
 return (RET_ERROR);
 }

 /*
 * If the key/data pair won't fit on a page, store it on overflow
 * pages. Only put the key on the overflow page if the pair are
 * still too big after moving the data to an overflow page.
 *
 * XXX
 * If the insert fails later on, the overflow pages aren't recovered.
 */
 dflags = 0;
 if (key->size + data->size > t->bt_ovflsize) {
 if (key->size > t->bt_ovflsize) {
storekey: if (__ovfl_put(t, key, &pg) == RET_ERROR)
 return (RET_ERROR);
 tkey.data = kb;
 tkey.size = NOVFLSIZE;
 memmove(kb, &pg, sizeof(pgno_t));
 memmove(kb + sizeof(pgno_t),
 &key->size, sizeof(u_int32_t));
 dflags |= P_BIGKEY;
 key = &tkey;
 }
 if (key->size + data->size > t->bt_ovflsize) {
 if (__ovfl_put(t, data, &pg) == RET_ERROR)
 return (RET_ERROR);
 tdata.data = db;
 tdata.size = NOVFLSIZE;
 memmove(db, &pg, sizeof(pgno_t));
 memmove(db + sizeof(pgno_t),
 &data->size, sizeof(u_int32_t));
 dflags |= P_BIGDATA;
 data = &tdata;
 }
 if (key->size + data->size > t->bt_ovflsize)
 goto storekey;
 }

 /* Replace the cursor. */
 if (flags == R_CURSOR) {
 if ((h = mpool_get(t->bt_mp, t->bt_cursor.pg.pgno, 0)) == NULL)
 return (RET_ERROR);
 idx = t->bt_cursor.pg.index;
 goto delete;
 }

 /*
 * Find the key to delete, or, the location at which to insert.
 * Bt_fast and __bt_search both pin the returned page.
 */
 if (t->bt_order == NOT || (e = bt_fast(t, key, data, &exact)) == NULL)
 if ((e = __bt_search(t, key, &exact)) == NULL)
 return (RET_ERROR);
 h = e->page;
 idx = e->index;

 /*
 * Add the key/data pair to the tree. If an identical key is already
 * in the tree, and R_NOOVERWRITE is set, an error is returned. If
 * R_NOOVERWRITE is not set, the key is either added (if duplicates are
 * permitted) or an error is returned.
 */
 switch (flags) {
 case R_NOOVERWRITE:
 if (!exact)
 break;
 mpool_put(t->bt_mp, h, 0);
 return (RET_SPECIAL);
 default:
 if (!exact || !F_ISSET(t, B_NODUPS))
 break;
 /*
 * !!!
 * Note, the delete may empty the page, so we need to put a
 * new entry into the page immediately.
 */
delete: if (__bt_dleaf(t, key, h, idx) == RET_ERROR) {
 mpool_put(t->bt_mp, h, 0);
 return (RET_ERROR);
 }
 break;
 }

 /*
 * If not enough room, or the user has put a ceiling on the number of
 * keys permitted in the page, split the page. The split code will
 * insert the key and data and unpin the current page. If inserting
 * into the offset array, shift the pointers up.
 */
 nbytes = NBLEAFDBT(key->size, data->size);
 if ((u_int32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t)) {
 if ((status = __bt_split(t, h, key,
 data, dflags, nbytes, idx)) != RET_SUCCESS)
 return (status);
 goto success;
 }

 if (idx < (nxtindex = NEXTINDEX(h)))
 memmove(h->linp + idx + 1, h->linp + idx,
 (nxtindex - idx) * sizeof(indx_t));
 h->lower += sizeof(indx_t);

 h->linp[idx] = h->upper -= nbytes;
 dest = (char *)h + h->upper;
 WR_BLEAF(dest, key, data, dflags);

 /* If the cursor is on this page, adjust it as necessary. */
 if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
 !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
 t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index >= idx)
 ++t->bt_cursor.pg.index;

 if (t->bt_order == NOT) {
 if (h->nextpg == P_INVALID) {
 if (idx == NEXTINDEX(h) - 1) {
 t->bt_order = FORWARD;
 t->bt_last.index = idx;
 t->bt_last.pgno = h->pgno;
 }
 } else if (h->prevpg == P_INVALID) {
 if (idx == 0) {
 t->bt_order = BACK;
 t->bt_last.index = 0;
 t->bt_last.pgno = h->pgno;
 }
 }
 }

 mpool_put(t->bt_mp, h, MPOOL_DIRTY);

success:
 if (flags == R_SETCURSOR)
 __bt_setcur(t, e->page->pgno, e->index);

 F_SET(t, B_MODIFIED);
 return (RET_SUCCESS);
}

#ifdef STATISTICS
u_long bt_cache_hit, bt_cache_miss;
#endif

/*
 * BT_FAST -- Do a quick check for sorted data.
 *
 * Parameters:
 * t: tree
 * key: key to insert
 *
 * Returns:
 * EPG for new record or NULL if not found.
 */
static EPG *
bt_fast(t, key, data, exactp)
 BTREE *t;
 const DBT *key, *data;
 int *exactp;
{
 PAGE *h;
 u_int32_t nbytes;
 int cmp;

 if ((h = mpool_get(t->bt_mp, t->bt_last.pgno, 0)) == NULL) {
 t->bt_order = NOT;
 return (NULL);
 }
 t->bt_cur.page = h;
 t->bt_cur.index = t->bt_last.index;

 /*
 * If won't fit in this page or have too many keys in this page,
 * have to search to get split stack.
 */
 nbytes = NBLEAFDBT(key->size, data->size);
 if ((u_int32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t))
 goto miss;

 if (t->bt_order == FORWARD) {
 if (t->bt_cur.page->nextpg != P_INVALID)
 goto miss;
 if (t->bt_cur.index != NEXTINDEX(h) - 1)
 goto miss;
 if ((cmp = __bt_cmp(t, key, &t->bt_cur)) < 0)
 goto miss;
 t->bt_last.index = cmp ? ++t->bt_cur.index : t->bt_cur.index;
 } else {
 if (t->bt_cur.page->prevpg != P_INVALID)
 goto miss;
 if (t->bt_cur.index != 0)
 goto miss;
 if ((cmp = __bt_cmp(t, key, &t->bt_cur)) > 0)
 goto miss;
 t->bt_last.index = 0;
 }
 *exactp = cmp == 0;
#ifdef STATISTICS
 ++bt_cache_hit;
#endif
 return (&t->bt_cur);

miss:
#ifdef STATISTICS
 ++bt_cache_miss;
#endif
 t->bt_order = NOT;
 mpool_put(t->bt_mp, h, 0);
 return (NULL);
}