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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)hash_page.c 8.7 (Berkeley) 8/16/94
33 * $FreeBSD: head/lib/libc/db/hash/hash_page.c 190500 2009-03-28 07:44:08Z delphij $
34 */
35
36 /*
37 * PACKAGE: hashing
38 *
39 * DESCRIPTION:
40 * Page manipulation for hashing package.
41 *
42 * ROUTINES:
43 *
44 * External
45 * __get_page
46 * __add_ovflpage
47 * Internal
48 * overflow_page
49 * open_temp
50 */
51
52 #include "namespace.h"
53 #include <sys/param.h>
54 #include <sys/file.h>
55
56 #include <errno.h>
57 #include <fcntl.h>
58 #include <signal.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 #include <unistd.h>
63 #ifdef DEBUG
64 #include <assert.h>
65 #endif
66 #include "un-namespace.h"
67
68 #include <db.h>
69 #include "hash.h"
70 #include "page.h"
71 #include "extern.h"
72
73 static uint32_t *fetch_bitmap(HTAB *, int);
74 static uint32_t first_free(uint32_t);
75 static int open_temp(HTAB *);
76 static uint16_t overflow_page(HTAB *);
77 static void putpair(char *, const DBT *, const DBT *);
78 static void squeeze_key(uint16_t *, const DBT *, const DBT *);
79 static int ugly_split(HTAB *, uint32_t, BUFHEAD *, BUFHEAD *, int, int);
80
81 #define PAGE_INIT(P) { \
82 ((uint16_t *)(P))[0] = 0; \
83 ((uint16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(uint16_t); \
84 ((uint16_t *)(P))[2] = hashp->BSIZE; \
85 }
86
87 /*
88 * This is called AFTER we have verified that there is room on the page for
89 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
90 * stuff on.
91 */
92 static void
putpair(char * p,const DBT * key,const DBT * val)93 putpair(char *p, const DBT *key, const DBT *val)
94 {
95 uint16_t *bp, n, off;
96
97 bp = (uint16_t *)p;
98
99 /* Enter the key first. */
100 n = bp[0];
101
102 off = OFFSET(bp) - key->size;
103 memmove(p + off, key->data, key->size);
104 bp[++n] = off;
105
106 /* Now the data. */
107 off -= val->size;
108 memmove(p + off, val->data, val->size);
109 bp[++n] = off;
110
111 /* Adjust page info. */
112 bp[0] = n;
113 bp[n + 1] = off - ((n + 3) * sizeof(uint16_t));
114 bp[n + 2] = off;
115 }
116
117 /*
118 * Returns:
119 * 0 OK
120 * -1 error
121 */
122 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)123 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
124 {
125 uint16_t *bp, newoff, pairlen;
126 int n;
127
128 bp = (uint16_t *)bufp->page;
129 n = bp[0];
130
131 if (bp[ndx + 1] < REAL_KEY)
132 return (__big_delete(hashp, bufp));
133 if (ndx != 1)
134 newoff = bp[ndx - 1];
135 else
136 newoff = hashp->BSIZE;
137 pairlen = newoff - bp[ndx + 1];
138
139 if (ndx != (n - 1)) {
140 /* Hard Case -- need to shuffle keys */
141 int i;
142 char *src = bufp->page + (int)OFFSET(bp);
143 char *dst = src + (int)pairlen;
144 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
145
146 /* Now adjust the pointers */
147 for (i = ndx + 2; i <= n; i += 2) {
148 if (bp[i + 1] == OVFLPAGE) {
149 bp[i - 2] = bp[i];
150 bp[i - 1] = bp[i + 1];
151 } else {
152 bp[i - 2] = bp[i] + pairlen;
153 bp[i - 1] = bp[i + 1] + pairlen;
154 }
155 }
156 if (ndx == hashp->cndx) {
157 /*
158 * We just removed pair we were "pointing" to.
159 * By moving back the cndx we ensure subsequent
160 * hash_seq() calls won't skip over any entries.
161 */
162 hashp->cndx -= 2;
163 }
164 }
165 /* Finally adjust the page data */
166 bp[n] = OFFSET(bp) + pairlen;
167 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(uint16_t);
168 bp[0] = n - 2;
169 hashp->NKEYS--;
170
171 bufp->flags |= BUF_MOD;
172 return (0);
173 }
174 /*
175 * Returns:
176 * 0 ==> OK
177 * -1 ==> Error
178 */
179 int
__split_page(HTAB * hashp,uint32_t obucket,uint32_t nbucket)180 __split_page(HTAB *hashp, uint32_t obucket, uint32_t nbucket)
181 {
182 BUFHEAD *new_bufp, *old_bufp;
183 uint16_t *ino;
184 char *np;
185 DBT key, val;
186 int n, ndx, retval;
187 uint16_t copyto, diff, off, moved;
188 char *op;
189
190 copyto = (uint16_t)hashp->BSIZE;
191 off = (uint16_t)hashp->BSIZE;
192 old_bufp = __get_buf(hashp, obucket, NULL, 0);
193 if (old_bufp == NULL)
194 return (-1);
195 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
196 if (new_bufp == NULL)
197 return (-1);
198
199 old_bufp->flags |= (BUF_MOD | BUF_PIN);
200 new_bufp->flags |= (BUF_MOD | BUF_PIN);
201
202 ino = (uint16_t *)(op = old_bufp->page);
203 np = new_bufp->page;
204
205 moved = 0;
206
207 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
208 if (ino[n + 1] < REAL_KEY) {
209 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
210 (int)copyto, (int)moved);
211 old_bufp->flags &= ~BUF_PIN;
212 new_bufp->flags &= ~BUF_PIN;
213 return (retval);
214
215 }
216 key.data = (unsigned char *)op + ino[n];
217 key.size = off - ino[n];
218
219 if (__call_hash(hashp, key.data, key.size) == obucket) {
220 /* Don't switch page */
221 diff = copyto - off;
222 if (diff) {
223 copyto = ino[n + 1] + diff;
224 memmove(op + copyto, op + ino[n + 1],
225 off - ino[n + 1]);
226 ino[ndx] = copyto + ino[n] - ino[n + 1];
227 ino[ndx + 1] = copyto;
228 } else
229 copyto = ino[n + 1];
230 ndx += 2;
231 } else {
232 /* Switch page */
233 val.data = (unsigned char *)op + ino[n + 1];
234 val.size = ino[n] - ino[n + 1];
235 putpair(np, &key, &val);
236 moved += 2;
237 }
238
239 off = ino[n + 1];
240 }
241
242 /* Now clean up the page */
243 ino[0] -= moved;
244 FREESPACE(ino) = copyto - sizeof(uint16_t) * (ino[0] + 3);
245 OFFSET(ino) = copyto;
246
247 #ifdef DEBUG3
248 fprintf(stderr, "split %d/%d\n",
249 ((uint16_t *)np)[0] / 2,
250 ((uint16_t *)op)[0] / 2);
251 #endif
252 /* unpin both pages */
253 old_bufp->flags &= ~BUF_PIN;
254 new_bufp->flags &= ~BUF_PIN;
255 return (0);
256 }
257
258 /*
259 * Called when we encounter an overflow or big key/data page during split
260 * handling. This is special cased since we have to begin checking whether
261 * the key/data pairs fit on their respective pages and because we may need
262 * overflow pages for both the old and new pages.
263 *
264 * The first page might be a page with regular key/data pairs in which case
265 * we have a regular overflow condition and just need to go on to the next
266 * page or it might be a big key/data pair in which case we need to fix the
267 * big key/data pair.
268 *
269 * Returns:
270 * 0 ==> success
271 * -1 ==> failure
272 */
273 static int
ugly_split(HTAB * hashp,uint32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)274 ugly_split(HTAB *hashp,
275 uint32_t obucket, /* Same as __split_page. */
276 BUFHEAD *old_bufp,
277 BUFHEAD *new_bufp,
278 int copyto, /* First byte on page which contains key/data values. */
279 int moved) /* Number of pairs moved to new page. */
280 {
281 BUFHEAD *bufp; /* Buffer header for ino */
282 uint16_t *ino; /* Page keys come off of */
283 uint16_t *np; /* New page */
284 uint16_t *op; /* Page keys go on to if they aren't moving */
285
286 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
287 DBT key, val;
288 SPLIT_RETURN ret;
289 uint16_t n, off, ov_addr, scopyto;
290 char *cino; /* Character value of ino */
291
292 bufp = old_bufp;
293 ino = (uint16_t *)old_bufp->page;
294 np = (uint16_t *)new_bufp->page;
295 op = (uint16_t *)old_bufp->page;
296 last_bfp = NULL;
297 scopyto = (uint16_t)copyto; /* ANSI */
298
299 n = ino[0] - 1;
300 while (n < ino[0]) {
301 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
302 if (__big_split(hashp, old_bufp,
303 new_bufp, bufp, bufp->addr, obucket, &ret))
304 return (-1);
305 old_bufp = ret.oldp;
306 if (!old_bufp)
307 return (-1);
308 op = (uint16_t *)old_bufp->page;
309 new_bufp = ret.newp;
310 if (!new_bufp)
311 return (-1);
312 np = (uint16_t *)new_bufp->page;
313 bufp = ret.nextp;
314 if (!bufp)
315 return (0);
316 cino = (char *)bufp->page;
317 ino = (uint16_t *)cino;
318 last_bfp = ret.nextp;
319 } else if (ino[n + 1] == OVFLPAGE) {
320 ov_addr = ino[n];
321 /*
322 * Fix up the old page -- the extra 2 are the fields
323 * which contained the overflow information.
324 */
325 ino[0] -= (moved + 2);
326 FREESPACE(ino) =
327 scopyto - sizeof(uint16_t) * (ino[0] + 3);
328 OFFSET(ino) = scopyto;
329
330 bufp = __get_buf(hashp, ov_addr, bufp, 0);
331 if (!bufp)
332 return (-1);
333
334 ino = (uint16_t *)bufp->page;
335 n = 1;
336 scopyto = hashp->BSIZE;
337 moved = 0;
338
339 if (last_bfp)
340 __free_ovflpage(hashp, last_bfp);
341 last_bfp = bufp;
342 }
343 /* Move regular sized pairs of there are any */
344 off = hashp->BSIZE;
345 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
346 cino = (char *)ino;
347 key.data = (unsigned char *)cino + ino[n];
348 key.size = off - ino[n];
349 val.data = (unsigned char *)cino + ino[n + 1];
350 val.size = ino[n] - ino[n + 1];
351 off = ino[n + 1];
352
353 if (__call_hash(hashp, key.data, key.size) == obucket) {
354 /* Keep on old page */
355 if (PAIRFITS(op, (&key), (&val)))
356 putpair((char *)op, &key, &val);
357 else {
358 old_bufp =
359 __add_ovflpage(hashp, old_bufp);
360 if (!old_bufp)
361 return (-1);
362 op = (uint16_t *)old_bufp->page;
363 putpair((char *)op, &key, &val);
364 }
365 old_bufp->flags |= BUF_MOD;
366 } else {
367 /* Move to new page */
368 if (PAIRFITS(np, (&key), (&val)))
369 putpair((char *)np, &key, &val);
370 else {
371 new_bufp =
372 __add_ovflpage(hashp, new_bufp);
373 if (!new_bufp)
374 return (-1);
375 np = (uint16_t *)new_bufp->page;
376 putpair((char *)np, &key, &val);
377 }
378 new_bufp->flags |= BUF_MOD;
379 }
380 }
381 }
382 if (last_bfp)
383 __free_ovflpage(hashp, last_bfp);
384 return (0);
385 }
386
387 /*
388 * Add the given pair to the page
389 *
390 * Returns:
391 * 0 ==> OK
392 * 1 ==> failure
393 */
394 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)395 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
396 {
397 uint16_t *bp, *sop;
398 int do_expand;
399
400 bp = (uint16_t *)bufp->page;
401 do_expand = 0;
402 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
403 /* Exception case */
404 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
405 /* This is the last page of a big key/data pair
406 and we need to add another page */
407 break;
408 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
409 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
410 if (!bufp)
411 return (-1);
412 bp = (uint16_t *)bufp->page;
413 } else if (bp[bp[0]] != OVFLPAGE) {
414 /* Short key/data pairs, no more pages */
415 break;
416 } else {
417 /* Try to squeeze key on this page */
418 if (bp[2] >= REAL_KEY &&
419 FREESPACE(bp) >= PAIRSIZE(key, val)) {
420 squeeze_key(bp, key, val);
421 goto stats;
422 } else {
423 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
424 if (!bufp)
425 return (-1);
426 bp = (uint16_t *)bufp->page;
427 }
428 }
429
430 if (PAIRFITS(bp, key, val))
431 putpair(bufp->page, key, val);
432 else {
433 do_expand = 1;
434 bufp = __add_ovflpage(hashp, bufp);
435 if (!bufp)
436 return (-1);
437 sop = (uint16_t *)bufp->page;
438
439 if (PAIRFITS(sop, key, val))
440 putpair((char *)sop, key, val);
441 else
442 if (__big_insert(hashp, bufp, key, val))
443 return (-1);
444 }
445 stats:
446 bufp->flags |= BUF_MOD;
447 /*
448 * If the average number of keys per bucket exceeds the fill factor,
449 * expand the table.
450 */
451 hashp->NKEYS++;
452 if (do_expand ||
453 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
454 return (__expand_table(hashp));
455 return (0);
456 }
457
458 /*
459 *
460 * Returns:
461 * pointer on success
462 * NULL on error
463 */
464 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)465 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
466 {
467 uint16_t *sp, ndx, ovfl_num;
468 #ifdef DEBUG1
469 int tmp1, tmp2;
470 #endif
471 sp = (uint16_t *)bufp->page;
472
473 /* Check if we are dynamically determining the fill factor */
474 if (hashp->FFACTOR == DEF_FFACTOR) {
475 hashp->FFACTOR = sp[0] >> 1;
476 if (hashp->FFACTOR < MIN_FFACTOR)
477 hashp->FFACTOR = MIN_FFACTOR;
478 }
479 bufp->flags |= BUF_MOD;
480 ovfl_num = overflow_page(hashp);
481 #ifdef DEBUG1
482 tmp1 = bufp->addr;
483 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
484 #endif
485 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
486 return (NULL);
487 bufp->ovfl->flags |= BUF_MOD;
488 #ifdef DEBUG1
489 fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
490 tmp1, tmp2, bufp->ovfl->addr);
491 #endif
492 ndx = sp[0];
493 /*
494 * Since a pair is allocated on a page only if there's room to add
495 * an overflow page, we know that the OVFL information will fit on
496 * the page.
497 */
498 sp[ndx + 4] = OFFSET(sp);
499 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
500 sp[ndx + 1] = ovfl_num;
501 sp[ndx + 2] = OVFLPAGE;
502 sp[0] = ndx + 2;
503 #ifdef HASH_STATISTICS
504 hash_overflows++;
505 #endif
506 return (bufp->ovfl);
507 }
508
509 /*
510 * Returns:
511 * 0 indicates SUCCESS
512 * -1 indicates FAILURE
513 */
514 int
__get_page(HTAB * hashp,char * p,uint32_t bucket,int is_bucket,int is_disk,int is_bitmap)515 __get_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_disk,
516 int is_bitmap)
517 {
518 int fd, page, size, rsize;
519 uint16_t *bp;
520
521 fd = hashp->fp;
522 size = hashp->BSIZE;
523
524 if ((fd == -1) || !is_disk) {
525 PAGE_INIT(p);
526 return (0);
527 }
528 if (is_bucket)
529 page = BUCKET_TO_PAGE(bucket);
530 else
531 page = OADDR_TO_PAGE(bucket);
532 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
533 return (-1);
534 bp = (uint16_t *)p;
535 if (!rsize)
536 bp[0] = 0; /* We hit the EOF, so initialize a new page */
537 else
538 if (rsize != size) {
539 errno = EFTYPE;
540 return (-1);
541 }
542 if (!is_bitmap && !bp[0]) {
543 PAGE_INIT(p);
544 } else
545 if (hashp->LORDER != BYTE_ORDER) {
546 int i, max;
547
548 if (is_bitmap) {
549 max = hashp->BSIZE >> 2; /* divide by 4 */
550 for (i = 0; i < max; i++)
551 M_32_SWAP(((int *)p)[i]);
552 } else {
553 M_16_SWAP(bp[0]);
554 max = bp[0] + 2;
555 for (i = 1; i <= max; i++)
556 M_16_SWAP(bp[i]);
557 }
558 }
559 return (0);
560 }
561
562 /*
563 * Write page p to disk
564 *
565 * Returns:
566 * 0 ==> OK
567 * -1 ==>failure
568 */
569 int
__put_page(HTAB * hashp,char * p,uint32_t bucket,int is_bucket,int is_bitmap)570 __put_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_bitmap)
571 {
572 int fd, page, size, wsize;
573
574 size = hashp->BSIZE;
575 if ((hashp->fp == -1) && open_temp(hashp))
576 return (-1);
577 fd = hashp->fp;
578
579 if (hashp->LORDER != BYTE_ORDER) {
580 int i, max;
581
582 if (is_bitmap) {
583 max = hashp->BSIZE >> 2; /* divide by 4 */
584 for (i = 0; i < max; i++)
585 M_32_SWAP(((int *)p)[i]);
586 } else {
587 max = ((uint16_t *)p)[0] + 2;
588 for (i = 0; i <= max; i++)
589 M_16_SWAP(((uint16_t *)p)[i]);
590 }
591 }
592 if (is_bucket)
593 page = BUCKET_TO_PAGE(bucket);
594 else
595 page = OADDR_TO_PAGE(bucket);
596 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
597 /* Errno is set */
598 return (-1);
599 if (wsize != size) {
600 errno = EFTYPE;
601 return (-1);
602 }
603 return (0);
604 }
605
606 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
607 /*
608 * Initialize a new bitmap page. Bitmap pages are left in memory
609 * once they are read in.
610 */
611 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)612 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
613 {
614 uint32_t *ip;
615 int clearbytes, clearints;
616
617 if ((ip = (uint32_t *)malloc(hashp->BSIZE)) == NULL)
618 return (1);
619 hashp->nmaps++;
620 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
621 clearbytes = clearints << INT_TO_BYTE;
622 memset((char *)ip, 0, clearbytes);
623 memset(((char *)ip) + clearbytes, 0xFF,
624 hashp->BSIZE - clearbytes);
625 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
626 SETBIT(ip, 0);
627 hashp->BITMAPS[ndx] = (uint16_t)pnum;
628 hashp->mapp[ndx] = ip;
629 return (0);
630 }
631
632 static uint32_t
first_free(uint32_t map)633 first_free(uint32_t map)
634 {
635 uint32_t i, mask;
636
637 mask = 0x1;
638 for (i = 0; i < BITS_PER_MAP; i++) {
639 if (!(mask & map))
640 return (i);
641 mask = mask << 1;
642 }
643 return (i);
644 }
645
646 static uint16_t
overflow_page(HTAB * hashp)647 overflow_page(HTAB *hashp)
648 {
649 uint32_t *freep;
650 int max_free, offset, splitnum;
651 uint16_t addr;
652 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
653 #ifdef DEBUG2
654 int tmp1, tmp2;
655 #endif
656 splitnum = hashp->OVFL_POINT;
657 max_free = hashp->SPARES[splitnum];
658
659 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
660 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
661
662 /* Look through all the free maps to find the first free block */
663 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
664 for ( i = first_page; i <= free_page; i++ ) {
665 if (!(freep = (uint32_t *)hashp->mapp[i]) &&
666 !(freep = fetch_bitmap(hashp, i)))
667 return (0);
668 if (i == free_page)
669 in_use_bits = free_bit;
670 else
671 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
672
673 if (i == first_page) {
674 bit = hashp->LAST_FREED &
675 ((hashp->BSIZE << BYTE_SHIFT) - 1);
676 j = bit / BITS_PER_MAP;
677 bit = rounddown2(bit, BITS_PER_MAP);
678 } else {
679 bit = 0;
680 j = 0;
681 }
682 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
683 if (freep[j] != ALL_SET)
684 goto found;
685 }
686
687 /* No Free Page Found */
688 hashp->LAST_FREED = hashp->SPARES[splitnum];
689 hashp->SPARES[splitnum]++;
690 offset = hashp->SPARES[splitnum] -
691 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
692
693 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
694 if (offset > SPLITMASK) {
695 if (++splitnum >= NCACHED) {
696 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
697 errno = EFBIG;
698 return (0);
699 }
700 hashp->OVFL_POINT = splitnum;
701 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
702 hashp->SPARES[splitnum-1]--;
703 offset = 1;
704 }
705
706 /* Check if we need to allocate a new bitmap page */
707 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
708 free_page++;
709 if (free_page >= NCACHED) {
710 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
711 errno = EFBIG;
712 return (0);
713 }
714 /*
715 * This is tricky. The 1 indicates that you want the new page
716 * allocated with 1 clear bit. Actually, you are going to
717 * allocate 2 pages from this map. The first is going to be
718 * the map page, the second is the overflow page we were
719 * looking for. The init_bitmap routine automatically, sets
720 * the first bit of itself to indicate that the bitmap itself
721 * is in use. We would explicitly set the second bit, but
722 * don't have to if we tell init_bitmap not to leave it clear
723 * in the first place.
724 */
725 if (__ibitmap(hashp,
726 (int)OADDR_OF(splitnum, offset), 1, free_page))
727 return (0);
728 hashp->SPARES[splitnum]++;
729 #ifdef DEBUG2
730 free_bit = 2;
731 #endif
732 offset++;
733 if (offset > SPLITMASK) {
734 if (++splitnum >= NCACHED) {
735 _write(STDERR_FILENO, OVMSG,
736 sizeof(OVMSG) - 1);
737 errno = EFBIG;
738 return (0);
739 }
740 hashp->OVFL_POINT = splitnum;
741 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
742 hashp->SPARES[splitnum-1]--;
743 offset = 0;
744 }
745 } else {
746 /*
747 * Free_bit addresses the last used bit. Bump it to address
748 * the first available bit.
749 */
750 free_bit++;
751 SETBIT(freep, free_bit);
752 }
753
754 /* Calculate address of the new overflow page */
755 addr = OADDR_OF(splitnum, offset);
756 #ifdef DEBUG2
757 fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
758 addr, free_bit, free_page);
759 #endif
760 return (addr);
761
762 found:
763 bit = bit + first_free(freep[j]);
764 SETBIT(freep, bit);
765 #ifdef DEBUG2
766 tmp1 = bit;
767 tmp2 = i;
768 #endif
769 /*
770 * Bits are addressed starting with 0, but overflow pages are addressed
771 * beginning at 1. Bit is a bit addressnumber, so we need to increment
772 * it to convert it to a page number.
773 */
774 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
775 if (bit >= hashp->LAST_FREED)
776 hashp->LAST_FREED = bit - 1;
777
778 /* Calculate the split number for this page */
779 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
780 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
781 if (offset >= SPLITMASK) {
782 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
783 errno = EFBIG;
784 return (0); /* Out of overflow pages */
785 }
786 addr = OADDR_OF(i, offset);
787 #ifdef DEBUG2
788 fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
789 addr, tmp1, tmp2);
790 #endif
791
792 /* Allocate and return the overflow page */
793 return (addr);
794 }
795
796 /*
797 * Mark this overflow page as free.
798 */
799 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)800 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
801 {
802 uint16_t addr;
803 uint32_t *freep;
804 int bit_address, free_page, free_bit;
805 uint16_t ndx;
806
807 addr = obufp->addr;
808 #ifdef DEBUG1
809 fprintf(stderr, "Freeing %d\n", addr);
810 #endif
811 ndx = (((uint16_t)addr) >> SPLITSHIFT);
812 bit_address =
813 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
814 if (bit_address < hashp->LAST_FREED)
815 hashp->LAST_FREED = bit_address;
816 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
817 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
818
819 if (!(freep = hashp->mapp[free_page]))
820 freep = fetch_bitmap(hashp, free_page);
821 #ifdef DEBUG
822 /*
823 * This had better never happen. It means we tried to read a bitmap
824 * that has already had overflow pages allocated off it, and we
825 * failed to read it from the file.
826 */
827 if (!freep)
828 assert(0);
829 #endif
830 CLRBIT(freep, free_bit);
831 #ifdef DEBUG2
832 fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
833 obufp->addr, free_bit, free_page);
834 #endif
835 __reclaim_buf(hashp, obufp);
836 }
837
838 /*
839 * Returns:
840 * 0 success
841 * -1 failure
842 */
843 static int
open_temp(HTAB * hashp)844 open_temp(HTAB *hashp)
845 {
846 sigset_t set, oset;
847 int len;
848 char *envtmp = NULL;
849 char path[MAXPATHLEN];
850
851 if (issetugid() == 0)
852 envtmp = getenv("TMPDIR");
853 len = snprintf(path,
854 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
855 if (len < 0 || len >= (int)sizeof(path)) {
856 errno = ENAMETOOLONG;
857 return (-1);
858 }
859
860 /* Block signals; make sure file goes away at process exit. */
861 sigfillset(&set);
862 _sigprocmask(SIG_BLOCK, &set, &oset);
863 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1) {
864 _unlink(path);
865 _fcntl(hashp->fp, F_SETFD, 1);
866 }
867 _sigprocmask(SIG_SETMASK, &oset, NULL);
868 return (hashp->fp != -1 ? 0 : -1);
869 }
870
871 /*
872 * We have to know that the key will fit, but the last entry on the page is
873 * an overflow pair, so we need to shift things.
874 */
875 static void
squeeze_key(uint16_t * sp,const DBT * key,const DBT * val)876 squeeze_key(uint16_t *sp, const DBT *key, const DBT *val)
877 {
878 char *p;
879 uint16_t free_space, n, off, pageno;
880
881 p = (char *)sp;
882 n = sp[0];
883 free_space = FREESPACE(sp);
884 off = OFFSET(sp);
885
886 pageno = sp[n - 1];
887 off -= key->size;
888 sp[n - 1] = off;
889 memmove(p + off, key->data, key->size);
890 off -= val->size;
891 sp[n] = off;
892 memmove(p + off, val->data, val->size);
893 sp[0] = n + 2;
894 sp[n + 1] = pageno;
895 sp[n + 2] = OVFLPAGE;
896 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
897 OFFSET(sp) = off;
898 }
899
900 static uint32_t *
fetch_bitmap(HTAB * hashp,int ndx)901 fetch_bitmap(HTAB *hashp, int ndx)
902 {
903 if (ndx >= hashp->nmaps)
904 return (NULL);
905 if ((hashp->mapp[ndx] = (uint32_t *)malloc(hashp->BSIZE)) == NULL)
906 return (NULL);
907 if (__get_page(hashp,
908 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
909 free(hashp->mapp[ndx]);
910 return (NULL);
911 }
912 return (hashp->mapp[ndx]);
913 }
914
915 #ifdef DEBUG4
916 int
print_chain(int addr)917 print_chain(int addr)
918 {
919 BUFHEAD *bufp;
920 short *bp, oaddr;
921
922 fprintf(stderr, "%d ", addr);
923 bufp = __get_buf(hashp, addr, NULL, 0);
924 bp = (short *)bufp->page;
925 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
926 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
927 oaddr = bp[bp[0] - 1];
928 fprintf(stderr, "%d ", (int)oaddr);
929 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
930 bp = (short *)bufp->page;
931 }
932 fprintf(stderr, "\n");
933 }
934 #endif
935