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Diffstat (limited to 'db/btree/bt_overflow.c')
| -rw-r--r-- | db/btree/bt_overflow.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/db/btree/bt_overflow.c b/db/btree/bt_overflow.c new file mode 100644 index 0000000000..b28b8e0471 --- /dev/null +++ b/db/btree/bt_overflow.c @@ -0,0 +1,228 @@ +/*- + * 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_overflow.c 8.5 (Berkeley) 7/16/94"; +#endif /* LIBC_SCCS and not lint */ + +#include <sys/param.h> + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include <db.h> +#include "btree.h" + +/* + * Big key/data code. + * + * Big key and data entries are stored on linked lists of pages. The initial + * reference is byte string stored with the key or data and is the page number + * and size. The actual record is stored in a chain of pages linked by the + * nextpg field of the PAGE header. + * + * The first page of the chain has a special property. If the record is used + * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set + * in the header. + * + * XXX + * A single DBT is written to each chain, so a lot of space on the last page + * is wasted. This is a fairly major bug for some data sets. + */ + +/* + * __OVFL_GET -- Get an overflow key/data item. + * + * Parameters: + * t: tree + * p: pointer to { pgno_t, u_int32_t } + * buf: storage address + * bufsz: storage size + * + * Returns: + * RET_ERROR, RET_SUCCESS + */ +int +__ovfl_get(t, p, ssz, buf, bufsz) + BTREE *t; + void *p; + size_t *ssz; + void **buf; + size_t *bufsz; +{ + PAGE *h; + pgno_t pg; + size_t nb, plen; + u_int32_t sz; + + memmove(&pg, p, sizeof(pgno_t)); + memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); + *ssz = sz; + +#ifdef DEBUG + if (pg == P_INVALID || sz == 0) + abort(); +#endif + /* Make the buffer bigger as necessary. */ + if (*bufsz < sz) { + *buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz)); + if (*buf == NULL) + return (RET_ERROR); + *bufsz = sz; + } + + /* + * Step through the linked list of pages, copying the data on each one + * into the buffer. Never copy more than the data's length. + */ + plen = t->bt_psize - BTDATAOFF; + for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { + if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) + return (RET_ERROR); + + nb = MIN(sz, plen); + memmove(p, (char *)h + BTDATAOFF, nb); + mpool_put(t->bt_mp, h, 0); + + if ((sz -= nb) == 0) + break; + } + return (RET_SUCCESS); +} + +/* + * __OVFL_PUT -- Store an overflow key/data item. + * + * Parameters: + * t: tree + * data: DBT to store + * pgno: storage page number + * + * Returns: + * RET_ERROR, RET_SUCCESS + */ +int +__ovfl_put(t, dbt, pg) + BTREE *t; + const DBT *dbt; + pgno_t *pg; +{ + PAGE *h, *last; + void *p; + pgno_t npg; + size_t nb, plen; + u_int32_t sz; + + /* + * Allocate pages and copy the key/data record into them. Store the + * number of the first page in the chain. + */ + plen = t->bt_psize - BTDATAOFF; + for (last = NULL, p = dbt->data, sz = dbt->size;; + p = (char *)p + plen, last = h) { + if ((h = __bt_new(t, &npg)) == NULL) + return (RET_ERROR); + + h->pgno = npg; + h->nextpg = h->prevpg = P_INVALID; + h->flags = P_OVERFLOW; + h->lower = h->upper = 0; + + nb = MIN(sz, plen); + memmove((char *)h + BTDATAOFF, p, nb); + + if (last) { + last->nextpg = h->pgno; + mpool_put(t->bt_mp, last, MPOOL_DIRTY); + } else + *pg = h->pgno; + + if ((sz -= nb) == 0) { + mpool_put(t->bt_mp, h, MPOOL_DIRTY); + break; + } + } + return (RET_SUCCESS); +} + +/* + * __OVFL_DELETE -- Delete an overflow chain. + * + * Parameters: + * t: tree + * p: pointer to { pgno_t, u_int32_t } + * + * Returns: + * RET_ERROR, RET_SUCCESS + */ +int +__ovfl_delete(t, p) + BTREE *t; + void *p; +{ + PAGE *h; + pgno_t pg; + size_t plen; + u_int32_t sz; + + memmove(&pg, p, sizeof(pgno_t)); + memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); + +#ifdef DEBUG + if (pg == P_INVALID || sz == 0) + abort(); +#endif + if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) + return (RET_ERROR); + + /* Don't delete chains used by internal pages. */ + if (h->flags & P_PRESERVE) { + mpool_put(t->bt_mp, h, 0); + return (RET_SUCCESS); + } + + /* Step through the chain, calling the free routine for each page. */ + for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { + pg = h->nextpg; + __bt_free(t, h); + if (sz <= plen) + break; + if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) + return (RET_ERROR); + } + return (RET_SUCCESS); +} |