source: trunk/src/emx/bsd/db/hash/hash_page.c@ 272

Last change on this file since 272 was 272, checked in by bird, 23 years ago

Initial revision
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  • Property svn:executable set to *
File size: 23.3 KB
Line 
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
37#if defined(LIBC_SCCS) && !defined(lint)
38static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94";
39#endif /* LIBC_SCCS and not lint */
40
41/*
42 * PACKAGE: hashing
43 *
44 * DESCRIPTION:
45 * Page manipulation for hashing package.
46 *
47 * ROUTINES:
48 *
49 * External
50 * __get_page
51 * __add_ovflpage
52 * Internal
53 * overflow_page
54 * open_temp
55 */
56
57#include <sys/types.h>
58#ifdef __EMX__
59#include <sys/param.h>
60#endif /* __EMX__ */
61
62#include <errno.h>
63#include <fcntl.h>
64#include <signal.h>
65#include <stdio.h>
66#include <stdlib.h>
67#include <string.h>
68#include <unistd.h>
69#ifdef DEBUG
70#include <assert.h>
71#endif
72
73#include <db.h>
74#include "hash.h"
75#include "page.h"
76#include "extern.h"
77
78static u_int32_t *fetch_bitmap __P((HTAB *, int));
79static u_int32_t first_free __P((u_int32_t));
80static int open_temp __P((HTAB *));
81static u_int16_t overflow_page __P((HTAB *));
82static void putpair __P((char *, const DBT *, const DBT *));
83static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *));
84static int ugly_split
85 __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int));
86
87#define PAGE_INIT(P) { \
88 ((u_int16_t *)(P))[0] = 0; \
89 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
90 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
91}
92
93/*
94 * This is called AFTER we have verified that there is room on the page for
95 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
96 * stuff on.
97 */
98static void
99putpair(p, key, val)
100 char *p;
101 const DBT *key, *val;
102{
103 register u_int16_t *bp, n, off;
104
105 bp = (u_int16_t *)p;
106
107 /* Enter the key first. */
108 n = bp[0];
109
110 off = OFFSET(bp) - key->size;
111 memmove(p + off, key->data, key->size);
112 bp[++n] = off;
113
114 /* Now the data. */
115 off -= val->size;
116 memmove(p + off, val->data, val->size);
117 bp[++n] = off;
118
119 /* Adjust page info. */
120 bp[0] = n;
121 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
122 bp[n + 2] = off;
123}
124
125/*
126 * Returns:
127 * 0 OK
128 * -1 error
129 */
130extern int
131__delpair(hashp, bufp, ndx)
132 HTAB *hashp;
133 BUFHEAD *bufp;
134 register int ndx;
135{
136 register u_int16_t *bp, newoff;
137 register int n;
138 u_int16_t pairlen;
139
140 bp = (u_int16_t *)bufp->page;
141 n = bp[0];
142
143 if (bp[ndx + 1] < REAL_KEY)
144 return (__big_delete(hashp, bufp));
145 if (ndx != 1)
146 newoff = bp[ndx - 1];
147 else
148 newoff = hashp->BSIZE;
149 pairlen = newoff - bp[ndx + 1];
150
151 if (ndx != (n - 1)) {
152 /* Hard Case -- need to shuffle keys */
153 register int i;
154 register char *src = bufp->page + (int)OFFSET(bp);
155 register char *dst = src + (int)pairlen;
156 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
157
158 /* Now adjust the pointers */
159 for (i = ndx + 2; i <= n; i += 2) {
160 if (bp[i + 1] == OVFLPAGE) {
161 bp[i - 2] = bp[i];
162 bp[i - 1] = bp[i + 1];
163 } else {
164 bp[i - 2] = bp[i] + pairlen;
165 bp[i - 1] = bp[i + 1] + pairlen;
166 }
167 }
168 }
169 /* Finally adjust the page data */
170 bp[n] = OFFSET(bp) + pairlen;
171 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
172 bp[0] = n - 2;
173 hashp->NKEYS--;
174
175 bufp->flags |= BUF_MOD;
176 return (0);
177}
178/*
179 * Returns:
180 * 0 ==> OK
181 * -1 ==> Error
182 */
183extern int
184__split_page(hashp, obucket, nbucket)
185 HTAB *hashp;
186 u_int32_t obucket, nbucket;
187{
188 register BUFHEAD *new_bufp, *old_bufp;
189 register u_int16_t *ino;
190 register char *np;
191 DBT key, val;
192 int n, ndx, retval;
193 u_int16_t copyto, diff, off, moved;
194 char *op;
195
196 copyto = (u_int16_t)hashp->BSIZE;
197 off = (u_int16_t)hashp->BSIZE;
198 old_bufp = __get_buf(hashp, obucket, NULL, 0);
199 if (old_bufp == NULL)
200 return (-1);
201 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
202 if (new_bufp == NULL)
203 return (-1);
204
205 old_bufp->flags |= (BUF_MOD | BUF_PIN);
206 new_bufp->flags |= (BUF_MOD | BUF_PIN);
207
208 ino = (u_int16_t *)(op = old_bufp->page);
209 np = new_bufp->page;
210
211 moved = 0;
212
213 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
214 if (ino[n + 1] < REAL_KEY) {
215 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
216 (int)copyto, (int)moved);
217 old_bufp->flags &= ~BUF_PIN;
218 new_bufp->flags &= ~BUF_PIN;
219 return (retval);
220
221 }
222 key.data = (u_char *)op + ino[n];
223 key.size = off - ino[n];
224
225 if (__call_hash(hashp, key.data, key.size) == obucket) {
226 /* Don't switch page */
227 diff = copyto - off;
228 if (diff) {
229 copyto = ino[n + 1] + diff;
230 memmove(op + copyto, op + ino[n + 1],
231 off - ino[n + 1]);
232 ino[ndx] = copyto + ino[n] - ino[n + 1];
233 ino[ndx + 1] = copyto;
234 } else
235 copyto = ino[n + 1];
236 ndx += 2;
237 } else {
238 /* Switch page */
239 val.data = (u_char *)op + ino[n + 1];
240 val.size = ino[n] - ino[n + 1];
241 putpair(np, &key, &val);
242 moved += 2;
243 }
244
245 off = ino[n + 1];
246 }
247
248 /* Now clean up the page */
249 ino[0] -= moved;
250 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
251 OFFSET(ino) = copyto;
252
253#ifdef DEBUG3
254 (void)fprintf(stderr, "split %d/%d\n",
255 ((u_int16_t *)np)[0] / 2,
256 ((u_int16_t *)op)[0] / 2);
257#endif
258 /* unpin both pages */
259 old_bufp->flags &= ~BUF_PIN;
260 new_bufp->flags &= ~BUF_PIN;
261 return (0);
262}
263
264/*
265 * Called when we encounter an overflow or big key/data page during split
266 * handling. This is special cased since we have to begin checking whether
267 * the key/data pairs fit on their respective pages and because we may need
268 * overflow pages for both the old and new pages.
269 *
270 * The first page might be a page with regular key/data pairs in which case
271 * we have a regular overflow condition and just need to go on to the next
272 * page or it might be a big key/data pair in which case we need to fix the
273 * big key/data pair.
274 *
275 * Returns:
276 * 0 ==> success
277 * -1 ==> failure
278 */
279static int
280ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved)
281 HTAB *hashp;
282 u_int32_t obucket; /* Same as __split_page. */
283 BUFHEAD *old_bufp, *new_bufp;
284 int copyto; /* First byte on page which contains key/data values. */
285 int moved; /* Number of pairs moved to new page. */
286{
287 register BUFHEAD *bufp; /* Buffer header for ino */
288 register u_int16_t *ino; /* Page keys come off of */
289 register u_int16_t *np; /* New page */
290 register u_int16_t *op; /* Page keys go on to if they aren't moving */
291
292 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
293 DBT key, val;
294 SPLIT_RETURN ret;
295 u_int16_t n, off, ov_addr, scopyto;
296 char *cino; /* Character value of ino */
297
298 bufp = old_bufp;
299 ino = (u_int16_t *)old_bufp->page;
300 np = (u_int16_t *)new_bufp->page;
301 op = (u_int16_t *)old_bufp->page;
302 last_bfp = NULL;
303 scopyto = (u_int16_t)copyto; /* ANSI */
304
305 n = ino[0] - 1;
306 while (n < ino[0]) {
307 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
308 if (__big_split(hashp, old_bufp,
309 new_bufp, bufp, bufp->addr, obucket, &ret))
310 return (-1);
311 old_bufp = ret.oldp;
312 if (!old_bufp)
313 return (-1);
314 op = (u_int16_t *)old_bufp->page;
315 new_bufp = ret.newp;
316 if (!new_bufp)
317 return (-1);
318 np = (u_int16_t *)new_bufp->page;
319 bufp = ret.nextp;
320 if (!bufp)
321 return (0);
322 cino = (char *)bufp->page;
323 ino = (u_int16_t *)cino;
324 last_bfp = ret.nextp;
325 } else if (ino[n + 1] == OVFLPAGE) {
326 ov_addr = ino[n];
327 /*
328 * Fix up the old page -- the extra 2 are the fields
329 * which contained the overflow information.
330 */
331 ino[0] -= (moved + 2);
332 FREESPACE(ino) =
333 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
334 OFFSET(ino) = scopyto;
335
336 bufp = __get_buf(hashp, ov_addr, bufp, 0);
337 if (!bufp)
338 return (-1);
339
340 ino = (u_int16_t *)bufp->page;
341 n = 1;
342 scopyto = hashp->BSIZE;
343 moved = 0;
344
345 if (last_bfp)
346 __free_ovflpage(hashp, last_bfp);
347 last_bfp = bufp;
348 }
349 /* Move regular sized pairs of there are any */
350 off = hashp->BSIZE;
351 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
352 cino = (char *)ino;
353 key.data = (u_char *)cino + ino[n];
354 key.size = off - ino[n];
355 val.data = (u_char *)cino + ino[n + 1];
356 val.size = ino[n] - ino[n + 1];
357 off = ino[n + 1];
358
359 if (__call_hash(hashp, key.data, key.size) == obucket) {
360 /* Keep on old page */
361 if (PAIRFITS(op, (&key), (&val)))
362 putpair((char *)op, &key, &val);
363 else {
364 old_bufp =
365 __add_ovflpage(hashp, old_bufp);
366 if (!old_bufp)
367 return (-1);
368 op = (u_int16_t *)old_bufp->page;
369 putpair((char *)op, &key, &val);
370 }
371 old_bufp->flags |= BUF_MOD;
372 } else {
373 /* Move to new page */
374 if (PAIRFITS(np, (&key), (&val)))
375 putpair((char *)np, &key, &val);
376 else {
377 new_bufp =
378 __add_ovflpage(hashp, new_bufp);
379 if (!new_bufp)
380 return (-1);
381 np = (u_int16_t *)new_bufp->page;
382 putpair((char *)np, &key, &val);
383 }
384 new_bufp->flags |= BUF_MOD;
385 }
386 }
387 }
388 if (last_bfp)
389 __free_ovflpage(hashp, last_bfp);
390 return (0);
391}
392
393/*
394 * Add the given pair to the page
395 *
396 * Returns:
397 * 0 ==> OK
398 * 1 ==> failure
399 */
400extern int
401__addel(hashp, bufp, key, val)
402 HTAB *hashp;
403 BUFHEAD *bufp;
404 const DBT *key, *val;
405{
406 register u_int16_t *bp, *sop;
407 int do_expand;
408
409 bp = (u_int16_t *)bufp->page;
410 do_expand = 0;
411 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
412 /* Exception case */
413 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
414 /* This is the last page of a big key/data pair
415 and we need to add another page */
416 break;
417 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
418 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
419 if (!bufp)
420 return (-1);
421 bp = (u_int16_t *)bufp->page;
422 } else
423 /* Try to squeeze key on this page */
424 if (FREESPACE(bp) > PAIRSIZE(key, val)) {
425 squeeze_key(bp, key, val);
426 return (0);
427 } else {
428 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
429 if (!bufp)
430 return (-1);
431 bp = (u_int16_t *)bufp->page;
432 }
433
434 if (PAIRFITS(bp, key, val))
435 putpair(bufp->page, key, val);
436 else {
437 do_expand = 1;
438 bufp = __add_ovflpage(hashp, bufp);
439 if (!bufp)
440 return (-1);
441 sop = (u_int16_t *)bufp->page;
442
443 if (PAIRFITS(sop, key, val))
444 putpair((char *)sop, key, val);
445 else
446 if (__big_insert(hashp, bufp, key, val))
447 return (-1);
448 }
449 bufp->flags |= BUF_MOD;
450 /*
451 * If the average number of keys per bucket exceeds the fill factor,
452 * expand the table.
453 */
454 hashp->NKEYS++;
455 if (do_expand ||
456 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
457 return (__expand_table(hashp));
458 return (0);
459}
460
461/*
462 *
463 * Returns:
464 * pointer on success
465 * NULL on error
466 */
467extern BUFHEAD *
468__add_ovflpage(hashp, bufp)
469 HTAB *hashp;
470 BUFHEAD *bufp;
471{
472 register u_int16_t *sp;
473 u_int16_t ndx, ovfl_num;
474#ifdef DEBUG1
475 int tmp1, tmp2;
476#endif
477 sp = (u_int16_t *)bufp->page;
478
479 /* Check if we are dynamically determining the fill factor */
480 if (hashp->FFACTOR == DEF_FFACTOR) {
481 hashp->FFACTOR = sp[0] >> 1;
482 if (hashp->FFACTOR < MIN_FFACTOR)
483 hashp->FFACTOR = MIN_FFACTOR;
484 }
485 bufp->flags |= BUF_MOD;
486 ovfl_num = overflow_page(hashp);
487#ifdef DEBUG1
488 tmp1 = bufp->addr;
489 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
490#endif
491 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
492 return (NULL);
493 bufp->ovfl->flags |= BUF_MOD;
494#ifdef DEBUG1
495 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
496 tmp1, tmp2, bufp->ovfl->addr);
497#endif
498 ndx = sp[0];
499 /*
500 * Since a pair is allocated on a page only if there's room to add
501 * an overflow page, we know that the OVFL information will fit on
502 * the page.
503 */
504 sp[ndx + 4] = OFFSET(sp);
505 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
506 sp[ndx + 1] = ovfl_num;
507 sp[ndx + 2] = OVFLPAGE;
508 sp[0] = ndx + 2;
509#ifdef HASH_STATISTICS
510 hash_overflows++;
511#endif
512 return (bufp->ovfl);
513}
514
515/*
516 * Returns:
517 * 0 indicates SUCCESS
518 * -1 indicates FAILURE
519 */
520extern int
521__get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap)
522 HTAB *hashp;
523 char *p;
524 u_int32_t bucket;
525 int is_bucket, is_disk, is_bitmap;
526{
527 register int fd, page, size;
528 int rsize;
529 u_int16_t *bp;
530
531 fd = hashp->fp;
532 size = hashp->BSIZE;
533
534 if ((fd == -1) || !is_disk) {
535 PAGE_INIT(p);
536 return (0);
537 }
538 if (is_bucket)
539 page = BUCKET_TO_PAGE(bucket);
540 else
541 page = OADDR_TO_PAGE(bucket);
542 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
543 ((rsize = read(fd, p, size)) == -1))
544 return (-1);
545 bp = (u_int16_t *)p;
546 if (!rsize)
547 bp[0] = 0; /* We hit the EOF, so initialize a new page */
548 else
549 if (rsize != size) {
550 errno = EFTYPE;
551 return (-1);
552 }
553 if (!is_bitmap && !bp[0]) {
554 PAGE_INIT(p);
555 } else
556 if (hashp->LORDER != BYTE_ORDER) {
557 register int i, max;
558
559 if (is_bitmap) {
560 max = hashp->BSIZE >> 2; /* divide by 4 */
561 for (i = 0; i < max; i++)
562 M_32_SWAP(((int *)p)[i]);
563 } else {
564 M_16_SWAP(bp[0]);
565 max = bp[0] + 2;
566 for (i = 1; i <= max; i++)
567 M_16_SWAP(bp[i]);
568 }
569 }
570 return (0);
571}
572
573/*
574 * Write page p to disk
575 *
576 * Returns:
577 * 0 ==> OK
578 * -1 ==>failure
579 */
580extern int
581__put_page(hashp, p, bucket, is_bucket, is_bitmap)
582 HTAB *hashp;
583 char *p;
584 u_int32_t bucket;
585 int is_bucket, is_bitmap;
586{
587 register int fd, page, size;
588 int wsize;
589
590 size = hashp->BSIZE;
591 if ((hashp->fp == -1) && open_temp(hashp))
592 return (-1);
593 fd = hashp->fp;
594
595 if (hashp->LORDER != BYTE_ORDER) {
596 register int i;
597 register int max;
598
599 if (is_bitmap) {
600 max = hashp->BSIZE >> 2; /* divide by 4 */
601 for (i = 0; i < max; i++)
602 M_32_SWAP(((int *)p)[i]);
603 } else {
604 max = ((u_int16_t *)p)[0] + 2;
605 for (i = 0; i <= max; i++)
606 M_16_SWAP(((u_int16_t *)p)[i]);
607 }
608 }
609 if (is_bucket)
610 page = BUCKET_TO_PAGE(bucket);
611 else
612 page = OADDR_TO_PAGE(bucket);
613 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
614 ((wsize = write(fd, p, size)) == -1))
615 /* Errno is set */
616 return (-1);
617 if (wsize != size) {
618 errno = EFTYPE;
619 return (-1);
620 }
621 return (0);
622}
623
624#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
625/*
626 * Initialize a new bitmap page. Bitmap pages are left in memory
627 * once they are read in.
628 */
629extern int
630__ibitmap(hashp, pnum, nbits, ndx)
631 HTAB *hashp;
632 int pnum, nbits, ndx;
633{
634 u_int32_t *ip;
635 int clearbytes, clearints;
636
637 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
638 return (1);
639 hashp->nmaps++;
640 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
641 clearbytes = clearints << INT_TO_BYTE;
642 (void)memset((char *)ip, 0, clearbytes);
643 (void)memset(((char *)ip) + clearbytes, 0xFF,
644 hashp->BSIZE - clearbytes);
645 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
646 SETBIT(ip, 0);
647 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
648 hashp->mapp[ndx] = ip;
649 return (0);
650}
651
652static u_int32_t
653first_free(map)
654 u_int32_t map;
655{
656 register u_int32_t i, mask;
657
658 mask = 0x1;
659 for (i = 0; i < BITS_PER_MAP; i++) {
660 if (!(mask & map))
661 return (i);
662 mask = mask << 1;
663 }
664 return (i);
665}
666
667static u_int16_t
668overflow_page(hashp)
669 HTAB *hashp;
670{
671 register u_int32_t *freep;
672 register int max_free, offset, splitnum;
673 u_int16_t addr;
674 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
675#ifdef DEBUG2
676 int tmp1, tmp2;
677#endif
678 splitnum = hashp->OVFL_POINT;
679 max_free = hashp->SPARES[splitnum];
680
681 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
682 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
683
684 /* Look through all the free maps to find the first free block */
685 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
686 for ( i = first_page; i <= free_page; i++ ) {
687 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
688 !(freep = fetch_bitmap(hashp, i)))
689 return (0);
690 if (i == free_page)
691 in_use_bits = free_bit;
692 else
693 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
694
695 if (i == first_page) {
696 bit = hashp->LAST_FREED &
697 ((hashp->BSIZE << BYTE_SHIFT) - 1);
698 j = bit / BITS_PER_MAP;
699 bit = bit & ~(BITS_PER_MAP - 1);
700 } else {
701 bit = 0;
702 j = 0;
703 }
704 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
705 if (freep[j] != ALL_SET)
706 goto found;
707 }
708
709 /* No Free Page Found */
710 hashp->LAST_FREED = hashp->SPARES[splitnum];
711 hashp->SPARES[splitnum]++;
712 offset = hashp->SPARES[splitnum] -
713 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
714
715#define OVMSG "HASH: Out of overflow pages. Increase page size\n"
716 if (offset > SPLITMASK) {
717 if (++splitnum >= NCACHED) {
718 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 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)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
732 return (0);
733 }
734 /*
735 * This is tricky. The 1 indicates that you want the new page
736 * allocated with 1 clear bit. Actually, you are going to
737 * allocate 2 pages from this map. The first is going to be
738 * the map page, the second is the overflow page we were
739 * looking for. The init_bitmap routine automatically, sets
740 * the first bit of itself to indicate that the bitmap itself
741 * is in use. We would explicitly set the second bit, but
742 * don't have to if we tell init_bitmap not to leave it clear
743 * in the first place.
744 */
745 if (__ibitmap(hashp,
746 (int)OADDR_OF(splitnum, offset), 1, free_page))
747 return (0);
748 hashp->SPARES[splitnum]++;
749#ifdef DEBUG2
750 free_bit = 2;
751#endif
752 offset++;
753 if (offset > SPLITMASK) {
754 if (++splitnum >= NCACHED) {
755 (void)write(STDERR_FILENO, OVMSG,
756 sizeof(OVMSG) - 1);
757 return (0);
758 }
759 hashp->OVFL_POINT = splitnum;
760 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
761 hashp->SPARES[splitnum-1]--;
762 offset = 0;
763 }
764 } else {
765 /*
766 * Free_bit addresses the last used bit. Bump it to address
767 * the first available bit.
768 */
769 free_bit++;
770 SETBIT(freep, free_bit);
771 }
772
773 /* Calculate address of the new overflow page */
774 addr = OADDR_OF(splitnum, offset);
775#ifdef DEBUG2
776 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
777 addr, free_bit, free_page);
778#endif
779 return (addr);
780
781found:
782 bit = bit + first_free(freep[j]);
783 SETBIT(freep, bit);
784#ifdef DEBUG2
785 tmp1 = bit;
786 tmp2 = i;
787#endif
788 /*
789 * Bits are addressed starting with 0, but overflow pages are addressed
790 * beginning at 1. Bit is a bit addressnumber, so we need to increment
791 * it to convert it to a page number.
792 */
793 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
794 if (bit >= hashp->LAST_FREED)
795 hashp->LAST_FREED = bit - 1;
796
797 /* Calculate the split number for this page */
798 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
799 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
800 if (offset >= SPLITMASK)
801 return (0); /* Out of overflow pages */
802 addr = OADDR_OF(i, offset);
803#ifdef DEBUG2
804 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
805 addr, tmp1, tmp2);
806#endif
807
808 /* Allocate and return the overflow page */
809 return (addr);
810}
811
812/*
813 * Mark this overflow page as free.
814 */
815extern void
816__free_ovflpage(hashp, obufp)
817 HTAB *hashp;
818 BUFHEAD *obufp;
819{
820 register u_int16_t addr;
821 u_int32_t *freep;
822 int bit_address, free_page, free_bit;
823 u_int16_t ndx;
824
825 addr = obufp->addr;
826#ifdef DEBUG1
827 (void)fprintf(stderr, "Freeing %d\n", addr);
828#endif
829 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
830 bit_address =
831 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
832 if (bit_address < hashp->LAST_FREED)
833 hashp->LAST_FREED = bit_address;
834 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
835 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
836
837 if (!(freep = hashp->mapp[free_page]))
838 freep = fetch_bitmap(hashp, free_page);
839#ifdef DEBUG
840 /*
841 * This had better never happen. It means we tried to read a bitmap
842 * that has already had overflow pages allocated off it, and we
843 * failed to read it from the file.
844 */
845 if (!freep)
846 assert(0);
847#endif
848 CLRBIT(freep, free_bit);
849#ifdef DEBUG2
850 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
851 obufp->addr, free_bit, free_page);
852#endif
853 __reclaim_buf(hashp, obufp);
854}
855
856/*
857 * Returns:
858 * 0 success
859 * -1 failure
860 */
861static int
862open_temp(hashp)
863 HTAB *hashp;
864{
865 sigset_t set, oset;
866#ifdef __EMX__
867 char namestr[] = "hsXXXXXX";
868#else /* not __EMX__ */
869 static char namestr[] = "_hashXXXXXX";
870#endif /* not __EMX__ */
871
872 /* Block signals; make sure file goes away at process exit. */
873 (void)sigfillset(&set);
874 (void)sigprocmask(SIG_BLOCK, &set, &oset);
875 if ((hashp->fp = mkstemp(namestr)) != -1) {
876#ifdef __EMX__
877 char absname[MAXPATHLEN];
878 setmode (hashp->fp, O_BINARY);
879 if (_abspath (absname, namestr, sizeof (absname)) == 0)
880 hashp->tempname = strdup (absname);
881#else /* not __EMX__ */
882 (void)unlink(namestr);
883#endif /* not __EMX__ */
884 (void)fcntl(hashp->fp, F_SETFD, 1);
885 }
886 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
887 return (hashp->fp != -1 ? 0 : -1);
888}
889
890/*
891 * We have to know that the key will fit, but the last entry on the page is
892 * an overflow pair, so we need to shift things.
893 */
894static void
895squeeze_key(sp, key, val)
896 u_int16_t *sp;
897 const DBT *key, *val;
898{
899 register char *p;
900 u_int16_t free_space, n, off, pageno;
901
902 p = (char *)sp;
903 n = sp[0];
904 free_space = FREESPACE(sp);
905 off = OFFSET(sp);
906
907 pageno = sp[n - 1];
908 off -= key->size;
909 sp[n - 1] = off;
910 memmove(p + off, key->data, key->size);
911 off -= val->size;
912 sp[n] = off;
913 memmove(p + off, val->data, val->size);
914 sp[0] = n + 2;
915 sp[n + 1] = pageno;
916 sp[n + 2] = OVFLPAGE;
917 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
918 OFFSET(sp) = off;
919}
920
921static u_int32_t *
922fetch_bitmap(hashp, ndx)
923 HTAB *hashp;
924 int ndx;
925{
926 if (ndx >= hashp->nmaps)
927 return (NULL);
928 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
929 return (NULL);
930 if (__get_page(hashp,
931 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
932 free(hashp->mapp[ndx]);
933 return (NULL);
934 }
935 return (hashp->mapp[ndx]);
936}
937
938#ifdef DEBUG4
939int
940print_chain(addr)
941 int addr;
942{
943 BUFHEAD *bufp;
944 short *bp, oaddr;
945
946 (void)fprintf(stderr, "%d ", addr);
947 bufp = __get_buf(hashp, addr, NULL, 0);
948 bp = (short *)bufp->page;
949 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
950 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
951 oaddr = bp[bp[0] - 1];
952 (void)fprintf(stderr, "%d ", (int)oaddr);
953 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
954 bp = (short *)bufp->page;
955 }
956 (void)fprintf(stderr, "\n");
957}
958#endif
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