1/*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Margo Seltzer.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * $FreeBSD: head/lib/libc/db/hash/hash_page.c 55837 2000-01-12 09:23:48Z jasone $
37 */
38
39#if defined(LIBC_SCCS) && !defined(lint)
40static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94";
41#endif /* LIBC_SCCS and not lint */
42
43/*
44 * PACKAGE: hashing
45 *
46 * DESCRIPTION:
47 * Page manipulation for hashing package.
48 *
49 * ROUTINES:
50 *
51 * External
52 * __get_page
53 * __add_ovflpage
54 * Internal
55 * overflow_page
56 * open_temp
57 */
58
59#include <sys/types.h>
60
61#include <errno.h>
62#include <fcntl.h>
63#include <signal.h>
64#include <stdio.h>
65#include <stdlib.h>
66#include <string.h>
67#include <unistd.h>
68#ifdef DEBUG
69#include <assert.h>
70#endif
71
72#include <db.h>
73#include "hash.h"
74#include "page.h"
75#include "extern.h"
76
77static u_int32_t *fetch_bitmap __P((HTAB *, int));
78static u_int32_t first_free __P((u_int32_t));
79static int open_temp __P((HTAB *));
80static u_int16_t overflow_page __P((HTAB *));
81static void putpair __P((char *, const DBT *, const DBT *));
82static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *));
83static int ugly_split
84 __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int));
85
86#define PAGE_INIT(P) { \
87 ((u_int16_t *)(P))[0] = 0; \
88 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
89 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
90}
91
92/*
93 * This is called AFTER we have verified that there is room on the page for
94 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
95 * stuff on.
96 */
97static void
98putpair(p, key, val)
99 char *p;
100 const DBT *key, *val;
101{
102 register u_int16_t *bp, n, off;
103
104 bp = (u_int16_t *)p;
105
106 /* Enter the key first. */
107 n = bp[0];
108
109 off = OFFSET(bp) - key->size;
110 memmove(p + off, key->data, key->size);
111 bp[++n] = off;
112
113 /* Now the data. */
114 off -= val->size;
115 memmove(p + off, val->data, val->size);
116 bp[++n] = off;
117
118 /* Adjust page info. */
119 bp[0] = n;
120 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
121 bp[n + 2] = off;
122}
123
124/*
125 * Returns:
126 * 0 OK
127 * -1 error
128 */
129extern int
130__delpair(hashp, bufp, ndx)
131 HTAB *hashp;
132 BUFHEAD *bufp;
133 register int ndx;
134{
135 register u_int16_t *bp, newoff;
136 register int n;
137 u_int16_t pairlen;
138
139 bp = (u_int16_t *)bufp->page;
140 n = bp[0];
141
142 if (bp[ndx + 1] < REAL_KEY)
143 return (__big_delete(hashp, bufp));
144 if (ndx != 1)
145 newoff = bp[ndx - 1];
146 else
147 newoff = hashp->BSIZE;
148 pairlen = newoff - bp[ndx + 1];
149
150 if (ndx != (n - 1)) {
151 /* Hard Case -- need to shuffle keys */
152 register int i;
153 register char *src = bufp->page + (int)OFFSET(bp);
154 register char *dst = src + (int)pairlen;
155 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
156
157 /* Now adjust the pointers */
158 for (i = ndx + 2; i <= n; i += 2) {
159 if (bp[i + 1] == OVFLPAGE) {
160 bp[i - 2] = bp[i];
161 bp[i - 1] = bp[i + 1];
162 } else {
163 bp[i - 2] = bp[i] + pairlen;
164 bp[i - 1] = bp[i + 1] + pairlen;
165 }
166 }
167 }
168 /* Finally adjust the page data */
169 bp[n] = OFFSET(bp) + pairlen;
170 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
171 bp[0] = n - 2;
172 hashp->NKEYS--;
173
174 bufp->flags |= BUF_MOD;
175 return (0);
176}
177/*
178 * Returns:
179 * 0 ==> OK
180 * -1 ==> Error
181 */
182extern int
183__split_page(hashp, obucket, nbucket)
184 HTAB *hashp;
185 u_int32_t obucket, nbucket;
186{
187 register BUFHEAD *new_bufp, *old_bufp;
188 register u_int16_t *ino;
189 register char *np;
190 DBT key, val;
191 int n, ndx, retval;
192 u_int16_t copyto, diff, off, moved;
193 char *op;
194
195 copyto = (u_int16_t)hashp->BSIZE;
196 off = (u_int16_t)hashp->BSIZE;
197 old_bufp = __get_buf(hashp, obucket, NULL, 0);
198 if (old_bufp == NULL)
199 return (-1);
200 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
201 if (new_bufp == NULL)
202 return (-1);
203
204 old_bufp->flags |= (BUF_MOD | BUF_PIN);
205 new_bufp->flags |= (BUF_MOD | BUF_PIN);
206
207 ino = (u_int16_t *)(op = old_bufp->page);
208 np = new_bufp->page;
209
210 moved = 0;
211
212 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
213 if (ino[n + 1] < REAL_KEY) {
214 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
215 (int)copyto, (int)moved);
216 old_bufp->flags &= ~BUF_PIN;
217 new_bufp->flags &= ~BUF_PIN;
218 return (retval);
219
220 }
221 key.data = (u_char *)op + ino[n];
222 key.size = off - ino[n];
223
224 if (__call_hash(hashp, key.data, key.size) == obucket) {
225 /* Don't switch page */
226 diff = copyto - off;
227 if (diff) {
228 copyto = ino[n + 1] + diff;
229 memmove(op + copyto, op + ino[n + 1],
230 off - ino[n + 1]);
231 ino[ndx] = copyto + ino[n] - ino[n + 1];
232 ino[ndx + 1] = copyto;
233 } else
234 copyto = ino[n + 1];
235 ndx += 2;
236 } else {
237 /* Switch page */
238 val.data = (u_char *)op + ino[n + 1];
239 val.size = ino[n] - ino[n + 1];
240 putpair(np, &key, &val);
241 moved += 2;
242 }
243
244 off = ino[n + 1];
245 }
246
247 /* Now clean up the page */
248 ino[0] -= moved;
249 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
250 OFFSET(ino) = copyto;
251
252#ifdef DEBUG3
253 (void)fprintf(stderr, "split %d/%d\n",
254 ((u_int16_t *)np)[0] / 2,
255 ((u_int16_t *)op)[0] / 2);
256#endif
257 /* unpin both pages */
258 old_bufp->flags &= ~BUF_PIN;
259 new_bufp->flags &= ~BUF_PIN;
260 return (0);
261}
262
263/*
264 * Called when we encounter an overflow or big key/data page during split
265 * handling. This is special cased since we have to begin checking whether
266 * the key/data pairs fit on their respective pages and because we may need
267 * overflow pages for both the old and new pages.
268 *
269 * The first page might be a page with regular key/data pairs in which case
270 * we have a regular overflow condition and just need to go on to the next
271 * page or it might be a big key/data pair in which case we need to fix the
272 * big key/data pair.
273 *
274 * Returns:
275 * 0 ==> success
276 * -1 ==> failure
277 */
278static int
279ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved)
280 HTAB *hashp;
281 u_int32_t obucket; /* Same as __split_page. */
282 BUFHEAD *old_bufp, *new_bufp;
283 int copyto; /* First byte on page which contains key/data values. */
284 int moved; /* Number of pairs moved to new page. */
285{
286 register BUFHEAD *bufp; /* Buffer header for ino */
287 register u_int16_t *ino; /* Page keys come off of */
288 register u_int16_t *np; /* New page */
289 register u_int16_t *op; /* Page keys go on to if they aren't moving */
290
291 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
292 DBT key, val;
293 SPLIT_RETURN ret;
294 u_int16_t n, off, ov_addr, scopyto;
295 char *cino; /* Character value of ino */
296
297 bufp = old_bufp;
298 ino = (u_int16_t *)old_bufp->page;
299 np = (u_int16_t *)new_bufp->page;
300 op = (u_int16_t *)old_bufp->page;
301 last_bfp = NULL;
302 scopyto = (u_int16_t)copyto; /* ANSI */
303
304 n = ino[0] - 1;
305 while (n < ino[0]) {
306 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
307 if (__big_split(hashp, old_bufp,
308 new_bufp, bufp, bufp->addr, obucket, &ret))
309 return (-1);
310 old_bufp = ret.oldp;
311 if (!old_bufp)
312 return (-1);
313 op = (u_int16_t *)old_bufp->page;
314 new_bufp = ret.newp;
315 if (!new_bufp)
316 return (-1);
317 np = (u_int16_t *)new_bufp->page;
318 bufp = ret.nextp;
319 if (!bufp)
320 return (0);
321 cino = (char *)bufp->page;
322 ino = (u_int16_t *)cino;
323 last_bfp = ret.nextp;
324 } else if (ino[n + 1] == OVFLPAGE) {
325 ov_addr = ino[n];
326 /*
327 * Fix up the old page -- the extra 2 are the fields
328 * which contained the overflow information.
329 */
330 ino[0] -= (moved + 2);
331 FREESPACE(ino) =
332 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
333 OFFSET(ino) = scopyto;
334
335 bufp = __get_buf(hashp, ov_addr, bufp, 0);
336 if (!bufp)
337 return (-1);
338
339 ino = (u_int16_t *)bufp->page;
340 n = 1;
341 scopyto = hashp->BSIZE;
342 moved = 0;
343
344 if (last_bfp)
345 __free_ovflpage(hashp, last_bfp);
346 last_bfp = bufp;
347 }
348 /* Move regular sized pairs of there are any */
349 off = hashp->BSIZE;
350 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
351 cino = (char *)ino;
352 key.data = (u_char *)cino + ino[n];
353 key.size = off - ino[n];
354 val.data = (u_char *)cino + ino[n + 1];
355 val.size = ino[n] - ino[n + 1];
356 off = ino[n + 1];
357
358 if (__call_hash(hashp, key.data, key.size) == obucket) {
359 /* Keep on old page */
360 if (PAIRFITS(op, (&key), (&val)))
361 putpair((char *)op, &key, &val);
362 else {
363 old_bufp =
364 __add_ovflpage(hashp, old_bufp);
365 if (!old_bufp)
366 return (-1);
367 op = (u_int16_t *)old_bufp->page;
368 putpair((char *)op, &key, &val);
369 }
370 old_bufp->flags |= BUF_MOD;
371 } else {
372 /* Move to new page */
373 if (PAIRFITS(np, (&key), (&val)))
374 putpair((char *)np, &key, &val);
375 else {
376 new_bufp =
377 __add_ovflpage(hashp, new_bufp);
378 if (!new_bufp)
379 return (-1);
380 np = (u_int16_t *)new_bufp->page;
381 putpair((char *)np, &key, &val);
382 }
383 new_bufp->flags |= BUF_MOD;
384 }
385 }
386 }
387 if (last_bfp)
388 __free_ovflpage(hashp, last_bfp);
389 return (0);
390}
391
392/*
393 * Add the given pair to the page
394 *
395 * Returns:
396 * 0 ==> OK
397 * 1 ==> failure
398 */
399extern int
400__addel(hashp, bufp, key, val)
401 HTAB *hashp;
402 BUFHEAD *bufp;
403 const DBT *key, *val;
404{
405 register u_int16_t *bp, *sop;
406 int do_expand;
407
408 bp = (u_int16_t *)bufp->page;
409 do_expand = 0;
410 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
411 /* Exception case */
412 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
413 /* This is the last page of a big key/data pair
414 and we need to add another page */
415 break;
416 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
417 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
418 if (!bufp)
419 return (-1);
420 bp = (u_int16_t *)bufp->page;
421 } else
422 /* Try to squeeze key on this page */
423 if (FREESPACE(bp) > PAIRSIZE(key, val)) {
424 squeeze_key(bp, key, val);
425 return (0);
426 } else {
427 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
428 if (!bufp)
429 return (-1);
430 bp = (u_int16_t *)bufp->page;
431 }
432
433 if (PAIRFITS(bp, key, val))
434 putpair(bufp->page, key, val);
435 else {
436 do_expand = 1;
437 bufp = __add_ovflpage(hashp, bufp);
438 if (!bufp)
439 return (-1);
440 sop = (u_int16_t *)bufp->page;
441
442 if (PAIRFITS(sop, key, val))
443 putpair((char *)sop, key, val);
444 else
445 if (__big_insert(hashp, bufp, key, val))
446 return (-1);
447 }
448 bufp->flags |= BUF_MOD;
449 /*
450 * If the average number of keys per bucket exceeds the fill factor,
451 * expand the table.
452 */
453 hashp->NKEYS++;
454 if (do_expand ||
455 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
456 return (__expand_table(hashp));
457 return (0);
458}
459
460/*
461 *
462 * Returns:
463 * pointer on success
464 * NULL on error
465 */
466extern BUFHEAD *
467__add_ovflpage(hashp, bufp)
468 HTAB *hashp;
469 BUFHEAD *bufp;
470{
471 register u_int16_t *sp;
472 u_int16_t ndx, ovfl_num;
473#ifdef DEBUG1
474 int tmp1, tmp2;
475#endif
476 sp = (u_int16_t *)bufp->page;
477
478 /* Check if we are dynamically determining the fill factor */
479 if (hashp->FFACTOR == DEF_FFACTOR) {
480 hashp->FFACTOR = sp[0] >> 1;
481 if (hashp->FFACTOR < MIN_FFACTOR)
482 hashp->FFACTOR = MIN_FFACTOR;
483 }
484 bufp->flags |= BUF_MOD;
485 ovfl_num = overflow_page(hashp);
486#ifdef DEBUG1
487 tmp1 = bufp->addr;
488 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
489#endif
490 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
491 return (NULL);
492 bufp->ovfl->flags |= BUF_MOD;
493#ifdef DEBUG1
494 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
495 tmp1, tmp2, bufp->ovfl->addr);
496#endif
497 ndx = sp[0];
498 /*
499 * Since a pair is allocated on a page only if there's room to add
500 * an overflow page, we know that the OVFL information will fit on
501 * the page.
502 */
503 sp[ndx + 4] = OFFSET(sp);
504 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
505 sp[ndx + 1] = ovfl_num;
506 sp[ndx + 2] = OVFLPAGE;
507 sp[0] = ndx + 2;
508#ifdef HASH_STATISTICS
509 hash_overflows++;
510#endif
511 return (bufp->ovfl);
512}
513
514/*
515 * Returns:
516 * 0 indicates SUCCESS
517 * -1 indicates FAILURE
518 */
519extern int
520__get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap)
521 HTAB *hashp;
522 char *p;
523 u_int32_t bucket;
524 int is_bucket, is_disk, is_bitmap;
525{
526 register int fd, page, size;
527 int rsize;
528 u_int16_t *bp;
529
530 fd = hashp->fp;
531 size = hashp->BSIZE;
532
533 if ((fd == -1) || !is_disk) {
534 PAGE_INIT(p);
535 return (0);
536 }
537 if (is_bucket)
538 page = BUCKET_TO_PAGE(bucket);
539 else
540 page = OADDR_TO_PAGE(bucket);
541 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
542 ((rsize = _libc_read(fd, p, size)) == -1))
543 return (-1);
544 bp = (u_int16_t *)p;
545 if (!rsize)
546 bp[0] = 0; /* We hit the EOF, so initialize a new page */
547 else
548 if (rsize != size) {
549 errno = EFTYPE;
550 return (-1);
551 }
552 if (!is_bitmap && !bp[0]) {
553 PAGE_INIT(p);
554 } else
555 if (hashp->LORDER != BYTE_ORDER) {
556 register int i, max;
557
558 if (is_bitmap) {
559 max = hashp->BSIZE >> 2; /* divide by 4 */
560 for (i = 0; i < max; i++)
561 M_32_SWAP(((int *)p)[i]);
562 } else {
563 M_16_SWAP(bp[0]);
564 max = bp[0] + 2;
565 for (i = 1; i <= max; i++)
566 M_16_SWAP(bp[i]);
567 }
568 }
569 return (0);
570}
571
572/*
573 * Write page p to disk
574 *
575 * Returns:
576 * 0 ==> OK
577 * -1 ==>failure
578 */
579extern int
580__put_page(hashp, p, bucket, is_bucket, is_bitmap)
581 HTAB *hashp;
582 char *p;
583 u_int32_t bucket;
584 int is_bucket, is_bitmap;
585{
586 register int fd, page, size;
587 int wsize;
588
589 size = hashp->BSIZE;
590 if ((hashp->fp == -1) && open_temp(hashp))
591 return (-1);
592 fd = hashp->fp;
593
594 if (hashp->LORDER != BYTE_ORDER) {
595 register int i;
596 register int max;
597
598 if (is_bitmap) {
599 max = hashp->BSIZE >> 2; /* divide by 4 */
600 for (i = 0; i < max; i++)
601 M_32_SWAP(((int *)p)[i]);
602 } else {
603 max = ((u_int16_t *)p)[0] + 2;
604 for (i = 0; i <= max; i++)
605 M_16_SWAP(((u_int16_t *)p)[i]);
606 }
607 }
608 if (is_bucket)
609 page = BUCKET_TO_PAGE(bucket);
610 else
611 page = OADDR_TO_PAGE(bucket);
612 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
613 ((wsize = _libc_write(fd, p, size)) == -1))
614 /* Errno is set */
615 return (-1);
616 if (wsize != size) {
617 errno = EFTYPE;
618 return (-1);
619 }
620 return (0);
621}
622
623#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
624/*
625 * Initialize a new bitmap page. Bitmap pages are left in memory
626 * once they are read in.
627 */
628extern int
629__ibitmap(hashp, pnum, nbits, ndx)
630 HTAB *hashp;
631 int pnum, nbits, ndx;
632{
633 u_int32_t *ip;
634 int clearbytes, clearints;
635
636 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
637 return (1);
638 hashp->nmaps++;
639 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
640 clearbytes = clearints << INT_TO_BYTE;
641 (void)memset((char *)ip, 0, clearbytes);
642 (void)memset(((char *)ip) + clearbytes, 0xFF,
643 hashp->BSIZE - clearbytes);
644 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
645 SETBIT(ip, 0);
646 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
647 hashp->mapp[ndx] = ip;
648 return (0);
649}
650
651static u_int32_t
652first_free(map)
653 u_int32_t map;
654{
655 register u_int32_t i, mask;
656
657 mask = 0x1;
658 for (i = 0; i < BITS_PER_MAP; i++) {
659 if (!(mask & map))
660 return (i);
661 mask = mask << 1;
662 }
663 return (i);
664}
665
666static u_int16_t
667overflow_page(hashp)
668 HTAB *hashp;
669{
670 register u_int32_t *freep;
671 register int max_free, offset, splitnum;
672 u_int16_t addr;
673 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
674#ifdef DEBUG2
675 int tmp1, tmp2;
676#endif
677 splitnum = hashp->OVFL_POINT;
678 max_free = hashp->SPARES[splitnum];
679
680 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
681 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
682
683 /* Look through all the free maps to find the first free block */
684 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
685 for ( i = first_page; i <= free_page; i++ ) {
686 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
687 !(freep = fetch_bitmap(hashp, i)))
688 return (0);
689 if (i == free_page)
690 in_use_bits = free_bit;
691 else
692 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
693
694 if (i == first_page) {
695 bit = hashp->LAST_FREED &
696 ((hashp->BSIZE << BYTE_SHIFT) - 1);
697 j = bit / BITS_PER_MAP;
698 bit = bit & ~(BITS_PER_MAP - 1);
699 } else {
700 bit = 0;
701 j = 0;
702 }
703 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
704 if (freep[j] != ALL_SET)
705 goto found;
706 }
707
708 /* No Free Page Found */
709 hashp->LAST_FREED = hashp->SPARES[splitnum];
710 hashp->SPARES[splitnum]++;
711 offset = hashp->SPARES[splitnum] -
712 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
713
714#define OVMSG "HASH: Out of overflow pages. Increase page size\n"
715 if (offset > SPLITMASK) {
716 if (++splitnum >= NCACHED) {
717 (void)_libc_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) -
718 1);
719 return (0);
720 }
721 hashp->OVFL_POINT = splitnum;
722 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
723 hashp->SPARES[splitnum-1]--;
724 offset = 1;
725 }
726
727 /* Check if we need to allocate a new bitmap page */
728 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
729 free_page++;
730 if (free_page >= NCACHED) {
731 (void)_libc_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) -
732 1);
733 return (0);
734 }
735 /*
736 * This is tricky. The 1 indicates that you want the new page
737 * allocated with 1 clear bit. Actually, you are going to
738 * allocate 2 pages from this map. The first is going to be
739 * the map page, the second is the overflow page we were
740 * looking for. The init_bitmap routine automatically, sets
741 * the first bit of itself to indicate that the bitmap itself
742 * is in use. We would explicitly set the second bit, but
743 * don't have to if we tell init_bitmap not to leave it clear
744 * in the first place.
745 */
746 if (__ibitmap(hashp,
747 (int)OADDR_OF(splitnum, offset), 1, free_page))
748 return (0);
749 hashp->SPARES[splitnum]++;
750#ifdef DEBUG2
751 free_bit = 2;
752#endif
753 offset++;
754 if (offset > SPLITMASK) {
755 if (++splitnum >= NCACHED) {
756 (void)_libc_write(STDERR_FILENO, OVMSG,
757 sizeof(OVMSG) - 1);
758 return (0);
759 }
760 hashp->OVFL_POINT = splitnum;
761 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
762 hashp->SPARES[splitnum-1]--;
763 offset = 0;
764 }
765 } else {
766 /*
767 * Free_bit addresses the last used bit. Bump it to address
768 * the first available bit.
769 */
770 free_bit++;
771 SETBIT(freep, free_bit);
772 }
773
774 /* Calculate address of the new overflow page */
775 addr = OADDR_OF(splitnum, offset);
776#ifdef DEBUG2
777 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
778 addr, free_bit, free_page);
779#endif
780 return (addr);
781
782found:
783 bit = bit + first_free(freep[j]);
784 SETBIT(freep, bit);
785#ifdef DEBUG2
786 tmp1 = bit;
787 tmp2 = i;
788#endif
789 /*
790 * Bits are addressed starting with 0, but overflow pages are addressed
791 * beginning at 1. Bit is a bit addressnumber, so we need to increment
792 * it to convert it to a page number.
793 */
794 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
795 if (bit >= hashp->LAST_FREED)
796 hashp->LAST_FREED = bit - 1;
797
798 /* Calculate the split number for this page */
799 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
800 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
801 if (offset >= SPLITMASK)
802 return (0); /* Out of overflow pages */
803 addr = OADDR_OF(i, offset);
804#ifdef DEBUG2
805 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
806 addr, tmp1, tmp2);
807#endif
808
809 /* Allocate and return the overflow page */
810 return (addr);
811}
812
813/*
814 * Mark this overflow page as free.
815 */
816extern void
817__free_ovflpage(hashp, obufp)
818 HTAB *hashp;
819 BUFHEAD *obufp;
820{
821 register u_int16_t addr;
822 u_int32_t *freep;
823 int bit_address, free_page, free_bit;
824 u_int16_t ndx;
825
826 addr = obufp->addr;
827#ifdef DEBUG1
828 (void)fprintf(stderr, "Freeing %d\n", addr);
829#endif
830 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
831 bit_address =
832 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
833 if (bit_address < hashp->LAST_FREED)
834 hashp->LAST_FREED = bit_address;
835 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
836 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
837
838 if (!(freep = hashp->mapp[free_page]))
839 freep = fetch_bitmap(hashp, free_page);
840#ifdef DEBUG
841 /*
842 * This had better never happen. It means we tried to read a bitmap
843 * that has already had overflow pages allocated off it, and we
844 * failed to read it from the file.
845 */
846 if (!freep)
847 assert(0);
848#endif
849 CLRBIT(freep, free_bit);
850#ifdef DEBUG2
851 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
852 obufp->addr, free_bit, free_page);
853#endif
854 __reclaim_buf(hashp, obufp);
855}
856
857/*
858 * Returns:
859 * 0 success
860 * -1 failure
861 */
862static int
863open_temp(hashp)
864 HTAB *hashp;
865{
866 sigset_t set, oset;
867 static char namestr[] = "_hashXXXXXX";
868
869 /* Block signals; make sure file goes away at process exit. */
870 (void)sigfillset(&set);
871 (void)sigprocmask(SIG_BLOCK, &set, &oset);
872 if ((hashp->fp = mkstemp(namestr)) != -1) {
873 (void)unlink(namestr);
874 (void)_libc_fcntl(hashp->fp, F_SETFD, 1);
875 }
876 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
877 return (hashp->fp != -1 ? 0 : -1);
878}
879
880/*
881 * We have to know that the key will fit, but the last entry on the page is
882 * an overflow pair, so we need to shift things.
883 */
884static void
885squeeze_key(sp, key, val)
886 u_int16_t *sp;
887 const DBT *key, *val;
888{
889 register char *p;
890 u_int16_t free_space, n, off, pageno;
891
892 p = (char *)sp;
893 n = sp[0];
894 free_space = FREESPACE(sp);
895 off = OFFSET(sp);
896
897 pageno = sp[n - 1];
898 off -= key->size;
899 sp[n - 1] = off;
900 memmove(p + off, key->data, key->size);
901 off -= val->size;
902 sp[n] = off;
903 memmove(p + off, val->data, val->size);
904 sp[0] = n + 2;
905 sp[n + 1] = pageno;
906 sp[n + 2] = OVFLPAGE;
907 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
908 OFFSET(sp) = off;
909}
910
911static u_int32_t *
912fetch_bitmap(hashp, ndx)
913 HTAB *hashp;
914 int ndx;
915{
916 if (ndx >= hashp->nmaps)
917 return (NULL);
918 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
919 return (NULL);
920 if (__get_page(hashp,
921 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
922 free(hashp->mapp[ndx]);
923 return (NULL);
924 }
925 return (hashp->mapp[ndx]);
926}
927
928#ifdef DEBUG4
929int
930print_chain(addr)
931 int addr;
932{
933 BUFHEAD *bufp;
934 short *bp, oaddr;
935
936 (void)fprintf(stderr, "%d ", addr);
937 bufp = __get_buf(hashp, addr, NULL, 0);
938 bp = (short *)bufp->page;
939 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
940 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
941 oaddr = bp[bp[0] - 1];
942 (void)fprintf(stderr, "%d ", (int)oaddr);
943 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
944 bp = (short *)bufp->page;
945 }
946 (void)fprintf(stderr, "\n");
947}
948#endif