1 /* $NetBSD: hash_page.c,v 1.29 2016/09/24 20:08:29 christos Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Margo Seltzer.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if HAVE_NBTOOL_CONFIG_H
36 #include "nbtool_config.h"
37 #endif
38
39 #include <sys/cdefs.h>
40 __RCSID("$NetBSD: hash_page.c,v 1.29 2016/09/24 20:08:29 christos Exp $");
41
42 /*
43 * PACKAGE: hashing
44 *
45 * DESCRIPTION:
46 * Page manipulation for hashing package.
47 *
48 * ROUTINES:
49 *
50 * External
51 * __get_page
52 * __add_ovflpage
53 * Internal
54 * overflow_page
55 */
56
57 #include "namespace.h"
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 #include <paths.h>
69 #include <assert.h>
70
71 #include <db.h>
72 #include "hash.h"
73 #include "page.h"
74 #include "extern.h"
75
76 static uint32_t *fetch_bitmap(HTAB *, int);
77 static uint32_t first_free(uint32_t);
78 static uint16_t overflow_page(HTAB *);
79 static void putpair(char *, const DBT *, const DBT *);
80 static void squeeze_key(uint16_t *, const DBT *, const DBT *);
81 static int ugly_split(HTAB *, uint32_t, BUFHEAD *, BUFHEAD *, int, int);
82
83 #define PAGE_INIT(P) { \
84 ((uint16_t *)(void *)(P))[0] = 0; \
85 temp = 3 * sizeof(uint16_t); \
86 _DIAGASSERT((size_t)HASH_BSIZE(hashp) >= temp); \
87 ((uint16_t *)(void *)(P))[1] = (uint16_t)(HASH_BSIZE(hashp) - temp); \
88 ((uint16_t *)(void *)(P))[2] = HASH_BSIZE(hashp); \
89 }
90
91 /*
92 * This is called AFTER we have verified that there is room on the page for
93 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
94 * stuff on.
95 */
96 static void
putpair(char * p,const DBT * key,const DBT * val)97 putpair(char *p, const DBT *key, const DBT *val)
98 {
99 uint16_t *bp, n, off;
100 size_t temp;
101
102 bp = (uint16_t *)(void *)p;
103
104 /* Enter the key first. */
105 n = bp[0];
106
107 temp = OFFSET(bp);
108 _DIAGASSERT(temp >= key->size);
109 off = (uint16_t)(temp - key->size);
110 memmove(p + off, key->data, key->size);
111 bp[++n] = off;
112
113 /* Now the data. */
114 _DIAGASSERT(off >= val->size);
115 off -= (uint16_t)val->size;
116 memmove(p + off, val->data, val->size);
117 bp[++n] = off;
118
119 /* Adjust page info. */
120 bp[0] = n;
121 temp = (n + 3) * sizeof(uint16_t);
122 _DIAGASSERT(off >= temp);
123 bp[n + 1] = (uint16_t)(off - temp);
124 bp[n + 2] = off;
125 }
126
127 /*
128 * Returns:
129 * 0 OK
130 * -1 error
131 */
132 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)133 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
134 {
135 uint16_t *bp, newoff;
136 int n;
137 uint16_t pairlen;
138 size_t temp;
139
140 bp = (uint16_t *)(void *)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 = HASH_BSIZE(hashp);
149 pairlen = newoff - bp[ndx + 1];
150
151 if (ndx != (n - 1)) {
152 /* Hard Case -- need to shuffle keys */
153 int i;
154 char *src = bufp->page + (int)OFFSET(bp);
155 char *dst = src + (int)pairlen;
156 memmove(dst, src, (size_t)(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 temp = bp[n + 1] + pairlen + 2 * sizeof(uint16_t);
172 _DIAGASSERT(temp <= 0xffff);
173 bp[n - 1] = (uint16_t)temp;
174 bp[0] = n - 2;
175 hashp->NKEYS--;
176
177 bufp->flags |= BUF_MOD;
178 return (0);
179 }
180 /*
181 * Returns:
182 * 0 ==> OK
183 * -1 ==> Error
184 */
185 int
__split_page(HTAB * hashp,uint32_t obucket,uint32_t nbucket)186 __split_page(HTAB *hashp, uint32_t obucket, uint32_t nbucket)
187 {
188 BUFHEAD *new_bufp, *old_bufp;
189 uint16_t *ino;
190 char *np;
191 DBT key, val;
192 int n, ndx, retval;
193 uint16_t copyto, diff, off, moved;
194 char *op;
195 size_t temp;
196
197 copyto = HASH_BSIZE(hashp);
198 off = HASH_BSIZE(hashp);
199 old_bufp = __get_buf(hashp, obucket, NULL, 0);
200 if (old_bufp == NULL)
201 return (-1);
202 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
203 if (new_bufp == NULL)
204 return (-1);
205
206 old_bufp->flags |= (BUF_MOD | BUF_PIN);
207 new_bufp->flags |= (BUF_MOD | BUF_PIN);
208
209 ino = (uint16_t *)(void *)(op = old_bufp->page);
210 np = new_bufp->page;
211
212 moved = 0;
213
214 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
215 if (ino[n + 1] < REAL_KEY) {
216 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
217 (int)copyto, (int)moved);
218 old_bufp->flags &= ~BUF_PIN;
219 new_bufp->flags &= ~BUF_PIN;
220 return (retval);
221
222 }
223 key.data = (uint8_t *)op + ino[n];
224 key.size = off - ino[n];
225
226 if (__call_hash(hashp, key.data, (int)key.size) == obucket) {
227 /* Don't switch page */
228 diff = copyto - off;
229 if (diff) {
230 copyto = ino[n + 1] + diff;
231 memmove(op + copyto, op + ino[n + 1],
232 (size_t)(off - ino[n + 1]));
233 ino[ndx] = copyto + ino[n] - ino[n + 1];
234 ino[ndx + 1] = copyto;
235 } else
236 copyto = ino[n + 1];
237 ndx += 2;
238 } else {
239 /* Switch page */
240 val.data = (uint8_t *)op + ino[n + 1];
241 val.size = ino[n] - ino[n + 1];
242 putpair(np, &key, &val);
243 moved += 2;
244 }
245
246 off = ino[n + 1];
247 }
248
249 /* Now clean up the page */
250 ino[0] -= moved;
251 temp = sizeof(uint16_t) * (ino[0] + 3);
252 _DIAGASSERT(copyto >= temp);
253 FREESPACE(ino) = (uint16_t)(copyto - temp);
254 OFFSET(ino) = copyto;
255
256 #ifdef DEBUG3
257 (void)fprintf(stderr, "split %d/%d\n",
258 ((uint16_t *)np)[0] / 2,
259 ((uint16_t *)op)[0] / 2);
260 #endif
261 /* unpin both pages */
262 old_bufp->flags &= ~BUF_PIN;
263 new_bufp->flags &= ~BUF_PIN;
264 return (0);
265 }
266
267 /*
268 * Called when we encounter an overflow or big key/data page during split
269 * handling. This is special cased since we have to begin checking whether
270 * the key/data pairs fit on their respective pages and because we may need
271 * overflow pages for both the old and new pages.
272 *
273 * The first page might be a page with regular key/data pairs in which case
274 * we have a regular overflow condition and just need to go on to the next
275 * page or it might be a big key/data pair in which case we need to fix the
276 * big key/data pair.
277 *
278 * Returns:
279 * 0 ==> success
280 * -1 ==> failure
281 */
282 static int
ugly_split(HTAB * hashp,uint32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)283 ugly_split(
284 HTAB *hashp,
285 uint32_t obucket, /* Same as __split_page. */
286 BUFHEAD *old_bufp,
287 BUFHEAD *new_bufp,
288 int copyto, /* First byte on page which contains key/data values. */
289 int moved /* Number of pairs moved to new page. */
290 )
291 {
292 BUFHEAD *bufp; /* Buffer header for ino */
293 uint16_t *ino; /* Page keys come off of */
294 uint16_t *np; /* New page */
295 uint16_t *op; /* Page keys go on to if they aren't moving */
296 size_t temp;
297
298 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
299 DBT key, val;
300 SPLIT_RETURN ret;
301 uint16_t n, off, ov_addr, scopyto;
302 char *cino; /* Character value of ino */
303
304 bufp = old_bufp;
305 ino = (uint16_t *)(void *)old_bufp->page;
306 np = (uint16_t *)(void *)new_bufp->page;
307 op = (uint16_t *)(void *)old_bufp->page;
308 last_bfp = NULL;
309 scopyto = (uint16_t)copyto; /* ANSI */
310
311 n = ino[0] - 1;
312 while (n < ino[0]) {
313 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
314 if (__big_split(hashp, old_bufp,
315 new_bufp, bufp, (int)bufp->addr, obucket, &ret))
316 return (-1);
317 old_bufp = ret.oldp;
318 if (!old_bufp)
319 return (-1);
320 op = (uint16_t *)(void *)old_bufp->page;
321 new_bufp = ret.newp;
322 if (!new_bufp)
323 return (-1);
324 np = (uint16_t *)(void *)new_bufp->page;
325 bufp = ret.nextp;
326 if (!bufp)
327 return (0);
328 cino = (char *)bufp->page;
329 ino = (uint16_t *)(void *)cino;
330 last_bfp = ret.nextp;
331 } else if (ino[n + 1] == OVFLPAGE) {
332 ov_addr = ino[n];
333 /*
334 * Fix up the old page -- the extra 2 are the fields
335 * which contained the overflow information.
336 */
337 ino[0] -= (moved + 2);
338 temp = sizeof(uint16_t) * (ino[0] + 3);
339 _DIAGASSERT(scopyto >= temp);
340 FREESPACE(ino) = (uint16_t)(scopyto - temp);
341 OFFSET(ino) = scopyto;
342
343 bufp = __get_buf(hashp, (uint32_t)ov_addr, bufp, 0);
344 if (!bufp)
345 return (-1);
346
347 ino = (uint16_t *)(void *)bufp->page;
348 n = 1;
349 scopyto = HASH_BSIZE(hashp);
350 moved = 0;
351
352 if (last_bfp)
353 __free_ovflpage(hashp, last_bfp);
354 last_bfp = bufp;
355 }
356 /* Move regular sized pairs of there are any */
357 off = HASH_BSIZE(hashp);
358 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
359 cino = (char *)(void *)ino;
360 key.data = (uint8_t *)cino + ino[n];
361 key.size = off - ino[n];
362 val.data = (uint8_t *)cino + ino[n + 1];
363 val.size = ino[n] - ino[n + 1];
364 off = ino[n + 1];
365
366 if (__call_hash(hashp, key.data, (int)key.size) == obucket) {
367 /* Keep on old page */
368 if (PAIRFITS(op, (&key), (&val)))
369 putpair((char *)(void *)op, &key, &val);
370 else {
371 old_bufp =
372 __add_ovflpage(hashp, old_bufp);
373 if (!old_bufp)
374 return (-1);
375 op = (uint16_t *)(void *)old_bufp->page;
376 putpair((char *)(void *)op, &key, &val);
377 }
378 old_bufp->flags |= BUF_MOD;
379 } else {
380 /* Move to new page */
381 if (PAIRFITS(np, (&key), (&val)))
382 putpair((char *)(void *)np, &key, &val);
383 else {
384 new_bufp =
385 __add_ovflpage(hashp, new_bufp);
386 if (!new_bufp)
387 return (-1);
388 np = (uint16_t *)(void *)new_bufp->page;
389 putpair((char *)(void *)np, &key, &val);
390 }
391 new_bufp->flags |= BUF_MOD;
392 }
393 }
394 }
395 if (last_bfp)
396 __free_ovflpage(hashp, last_bfp);
397 return (0);
398 }
399
400 /*
401 * Add the given pair to the page
402 *
403 * Returns:
404 * 0 ==> OK
405 * 1 ==> failure
406 */
407 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)408 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
409 {
410 uint16_t *bp, *sop;
411 int do_expand;
412
413 bp = (uint16_t *)(void *)bufp->page;
414 do_expand = 0;
415 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
416 /* Exception case */
417 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
418 /* This is the last page of a big key/data pair
419 and we need to add another page */
420 break;
421 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
422 bufp = __get_buf(hashp, (uint32_t)bp[bp[0] - 1], bufp,
423 0);
424 if (!bufp)
425 return (-1);
426 bp = (uint16_t *)(void *)bufp->page;
427 } else if (bp[bp[0]] != OVFLPAGE) {
428 /* Short key/data pairs, no more pages */
429 break;
430 } else {
431 /* Try to squeeze key on this page */
432 if (bp[2] >= REAL_KEY &&
433 FREESPACE(bp) >= PAIRSIZE(key, val)) {
434 squeeze_key(bp, key, val);
435 goto stats;
436 } else {
437 bufp = __get_buf(hashp,
438 (uint32_t)bp[bp[0] - 1], bufp, 0);
439 if (!bufp)
440 return (-1);
441 bp = (uint16_t *)(void *)bufp->page;
442 }
443 }
444
445 if (PAIRFITS(bp, key, val))
446 putpair(bufp->page, key, val);
447 else {
448 do_expand = 1;
449 bufp = __add_ovflpage(hashp, bufp);
450 if (!bufp)
451 return (-1);
452 sop = (uint16_t *)(void *)bufp->page;
453
454 if (PAIRFITS(sop, key, val))
455 putpair((char *)(void *)sop, key, val);
456 else
457 if (__big_insert(hashp, bufp, key, val))
458 return (-1);
459 }
460 stats:
461 bufp->flags |= BUF_MOD;
462 /*
463 * If the average number of keys per bucket exceeds the fill factor,
464 * expand the table.
465 */
466 hashp->NKEYS++;
467 if (do_expand ||
468 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
469 return (__expand_table(hashp));
470 return (0);
471 }
472
473 /*
474 *
475 * Returns:
476 * pointer on success
477 * NULL on error
478 */
479 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)480 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
481 {
482 uint16_t *sp;
483 uint16_t ndx, ovfl_num;
484 size_t temp;
485 #ifdef DEBUG1
486 int tmp1, tmp2;
487 #endif
488 sp = (uint16_t *)(void *)bufp->page;
489
490 /* Check if we are dynamically determining the fill factor */
491 if (hashp->FFACTOR == DEF_FFACTOR) {
492 hashp->FFACTOR = (uint32_t)sp[0] >> 1;
493 if (hashp->FFACTOR < MIN_FFACTOR)
494 hashp->FFACTOR = MIN_FFACTOR;
495 }
496 bufp->flags |= BUF_MOD;
497 ovfl_num = overflow_page(hashp);
498 #ifdef DEBUG1
499 tmp1 = bufp->addr;
500 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
501 #endif
502 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, (uint32_t)ovfl_num,
503 bufp, 1)))
504 return (NULL);
505 bufp->ovfl->flags |= BUF_MOD;
506 #ifdef DEBUG1
507 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
508 tmp1, tmp2, bufp->ovfl->addr);
509 #endif
510 ndx = sp[0];
511 /*
512 * Since a pair is allocated on a page only if there's room to add
513 * an overflow page, we know that the OVFL information will fit on
514 * the page.
515 */
516 sp[ndx + 4] = OFFSET(sp);
517 temp = FREESPACE(sp);
518 _DIAGASSERT(temp >= OVFLSIZE);
519 sp[ndx + 3] = (uint16_t)(temp - OVFLSIZE);
520 sp[ndx + 1] = ovfl_num;
521 sp[ndx + 2] = OVFLPAGE;
522 sp[0] = ndx + 2;
523 #ifdef HASH_STATISTICS
524 hash_overflows++;
525 #endif
526 return (bufp->ovfl);
527 }
528
529 /*
530 * Returns:
531 * 0 indicates SUCCESS
532 * -1 indicates FAILURE
533 */
534 int
__get_page(HTAB * hashp,char * p,uint32_t bucket,int is_bucket,int is_disk,int is_bitmap)535 __get_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_disk,
536 int is_bitmap)
537 {
538 int fd, page, size;
539 ssize_t rsize;
540 uint16_t *bp;
541 size_t temp;
542
543 fd = hashp->fp;
544 size = HASH_BSIZE(hashp);
545
546 if ((fd == -1) || !is_disk) {
547 PAGE_INIT(p);
548 return (0);
549 }
550 if (is_bucket)
551 page = BUCKET_TO_PAGE(bucket);
552 else
553 page = OADDR_TO_PAGE(bucket);
554 if ((rsize = pread(fd, p, (size_t)size, (off_t)page << hashp->BSHIFT)) == -1)
555 return (-1);
556 bp = (uint16_t *)(void *)p;
557 if (!rsize)
558 bp[0] = 0; /* We hit the EOF, so initialize a new page */
559 else
560 if (rsize != size) {
561 errno = EFTYPE;
562 return (-1);
563 }
564 if (!is_bitmap && !bp[0]) {
565 PAGE_INIT(p);
566 } else
567 if (hashp->LORDER != BYTE_ORDER) {
568 int i, max;
569
570 if (is_bitmap) {
571 max = (uint32_t)hashp->BSIZE >> 2; /* divide by 4 */
572 for (i = 0; i < max; i++)
573 M_32_SWAP(((int *)(void *)p)[i]);
574 } else {
575 M_16_SWAP(bp[0]);
576 max = bp[0] + 2;
577 for (i = 1; i <= max; i++)
578 M_16_SWAP(bp[i]);
579 }
580 }
581 return (0);
582 }
583
584 /*
585 * Write page p to disk
586 *
587 * Returns:
588 * 0 ==> OK
589 * -1 ==>failure
590 */
591 int
__put_page(HTAB * hashp,char * p,uint32_t bucket,int is_bucket,int is_bitmap)592 __put_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_bitmap)
593 {
594 int fd, page, size;
595 ssize_t wsize;
596 char pbuf[MAX_BSIZE];
597
598 size = HASH_BSIZE(hashp);
599 if ((hashp->fp == -1) && (hashp->fp = __dbtemp("_hash", NULL)) == -1)
600 return (-1);
601 fd = hashp->fp;
602
603 if (hashp->LORDER != BYTE_ORDER) {
604 int i;
605 int max;
606
607 memcpy(pbuf, p, size);
608 if (is_bitmap) {
609 max = (uint32_t)hashp->BSIZE >> 2; /* divide by 4 */
610 for (i = 0; i < max; i++)
611 M_32_SWAP(((int *)(void *)pbuf)[i]);
612 } else {
613 uint16_t *bp = (uint16_t *)(void *)pbuf;
614 max = bp[0] + 2;
615 for (i = 0; i <= max; i++)
616 M_16_SWAP(bp[i]);
617 }
618 p = pbuf;
619 }
620 if (is_bucket)
621 page = BUCKET_TO_PAGE(bucket);
622 else
623 page = OADDR_TO_PAGE(bucket);
624 if ((wsize = pwrite(fd, p, (size_t)size, (off_t)page << hashp->BSHIFT)) == -1)
625 /* Errno is set */
626 return (-1);
627 if (wsize != size) {
628 errno = EFTYPE;
629 return (-1);
630 }
631 return (0);
632 }
633
634 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
635 /*
636 * Initialize a new bitmap page. Bitmap pages are left in memory
637 * once they are read in.
638 */
639 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)640 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
641 {
642 uint32_t *ip;
643 int clearbytes, clearints;
644
645 if ((ip = malloc((size_t)hashp->BSIZE)) == NULL)
646 return (1);
647 hashp->nmaps++;
648 clearints = ((uint32_t)(nbits - 1) >> INT_BYTE_SHIFT) + 1;
649 clearbytes = clearints << INT_TO_BYTE;
650 (void)memset(ip, 0, (size_t)clearbytes);
651 (void)memset(((char *)(void *)ip) + clearbytes, 0xFF,
652 (size_t)(hashp->BSIZE - clearbytes));
653 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
654 SETBIT(ip, 0);
655 hashp->BITMAPS[ndx] = (uint16_t)pnum;
656 hashp->mapp[ndx] = ip;
657 return (0);
658 }
659
660 static uint32_t
first_free(uint32_t map)661 first_free(uint32_t map)
662 {
663 uint32_t i, mask;
664
665 mask = 0x1;
666 for (i = 0; i < BITS_PER_MAP; i++) {
667 if (!(mask & map))
668 return (i);
669 mask = mask << 1;
670 }
671 return (i);
672 }
673
674 static uint16_t
overflow_page(HTAB * hashp)675 overflow_page(HTAB *hashp)
676 {
677 uint32_t *freep = NULL;
678 int max_free, offset, splitnum;
679 uint16_t addr;
680 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
681 #ifdef DEBUG2
682 int tmp1, tmp2;
683 #endif
684 splitnum = hashp->OVFL_POINT;
685 max_free = hashp->SPARES[splitnum];
686
687 free_page = (uint32_t)(max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
688 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
689
690 /* Look through all the free maps to find the first free block */
691 first_page = (uint32_t)hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
692 for ( i = first_page; i <= free_page; i++ ) {
693 if (!(freep = (uint32_t *)hashp->mapp[i]) &&
694 !(freep = fetch_bitmap(hashp, i)))
695 return (0);
696 if (i == free_page)
697 in_use_bits = free_bit;
698 else
699 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
700
701 if (i == first_page) {
702 bit = hashp->LAST_FREED &
703 ((hashp->BSIZE << BYTE_SHIFT) - 1);
704 j = bit / BITS_PER_MAP;
705 bit = bit & ~(BITS_PER_MAP - 1);
706 } else {
707 bit = 0;
708 j = 0;
709 }
710 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
711 if (freep[j] != ALL_SET)
712 goto found;
713 }
714
715 /* No Free Page Found */
716 hashp->LAST_FREED = hashp->SPARES[splitnum];
717 hashp->SPARES[splitnum]++;
718 offset = hashp->SPARES[splitnum] -
719 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
720
721 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
722 if (offset > SPLITMASK) {
723 if (++splitnum >= NCACHED) {
724 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
725 errno = EFBIG;
726 return (0);
727 }
728 hashp->OVFL_POINT = splitnum;
729 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
730 hashp->SPARES[splitnum-1]--;
731 offset = 1;
732 }
733
734 /* Check if we need to allocate a new bitmap page */
735 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
736 free_page++;
737 if (free_page >= NCACHED) {
738 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
739 errno = EFBIG;
740 return (0);
741 }
742 /*
743 * This is tricky. The 1 indicates that you want the new page
744 * allocated with 1 clear bit. Actually, you are going to
745 * allocate 2 pages from this map. The first is going to be
746 * the map page, the second is the overflow page we were
747 * looking for. The init_bitmap routine automatically, sets
748 * the first bit of itself to indicate that the bitmap itself
749 * is in use. We would explicitly set the second bit, but
750 * don't have to if we tell init_bitmap not to leave it clear
751 * in the first place.
752 */
753 if (__ibitmap(hashp,
754 (int)OADDR_OF(splitnum, offset), 1, free_page))
755 return (0);
756 hashp->SPARES[splitnum]++;
757 #ifdef DEBUG2
758 free_bit = 2;
759 #endif
760 offset++;
761 if (offset > SPLITMASK) {
762 if (++splitnum >= NCACHED) {
763 (void)write(STDERR_FILENO, OVMSG,
764 sizeof(OVMSG) - 1);
765 errno = EFBIG;
766 return (0);
767 }
768 hashp->OVFL_POINT = splitnum;
769 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
770 hashp->SPARES[splitnum-1]--;
771 offset = 0;
772 }
773 } else {
774 /*
775 * Free_bit addresses the last used bit. Bump it to address
776 * the first available bit.
777 */
778 free_bit++;
779 SETBIT(freep, free_bit);
780 }
781
782 /* Calculate address of the new overflow page */
783 addr = OADDR_OF(splitnum, offset);
784 #ifdef DEBUG2
785 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
786 addr, free_bit, free_page);
787 #endif
788 return (addr);
789
790 found:
791 bit = bit + first_free(freep[j]);
792 SETBIT(freep, bit);
793 #ifdef DEBUG2
794 tmp1 = bit;
795 tmp2 = i;
796 #endif
797 /*
798 * Bits are addressed starting with 0, but overflow pages are addressed
799 * beginning at 1. Bit is a bit addressnumber, so we need to increment
800 * it to convert it to a page number.
801 */
802 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
803 if (bit >= hashp->LAST_FREED)
804 hashp->LAST_FREED = bit - 1;
805
806 /* Calculate the split number for this page */
807 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
808 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
809 if (offset >= SPLITMASK) {
810 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
811 errno = EFBIG;
812 return (0); /* Out of overflow pages */
813 }
814 addr = OADDR_OF(i, offset);
815 #ifdef DEBUG2
816 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
817 addr, tmp1, tmp2);
818 #endif
819
820 /* Allocate and return the overflow page */
821 return (addr);
822 }
823
824 /*
825 * Mark this overflow page as free.
826 */
827 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)828 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
829 {
830 uint16_t addr;
831 uint32_t *freep;
832 int bit_address, free_page, free_bit;
833 uint16_t ndx;
834
835 addr = obufp->addr;
836 #ifdef DEBUG1
837 (void)fprintf(stderr, "Freeing %d\n", addr);
838 #endif
839 ndx = (((uint32_t)addr) >> SPLITSHIFT);
840 bit_address =
841 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
842 if (bit_address < hashp->LAST_FREED)
843 hashp->LAST_FREED = bit_address;
844 free_page = ((uint32_t)bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
845 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
846
847 if (!(freep = hashp->mapp[free_page]))
848 freep = fetch_bitmap(hashp, free_page);
849 /*
850 * This had better never happen. It means we tried to read a bitmap
851 * that has already had overflow pages allocated off it, and we
852 * failed to read it from the file.
853 */
854 _DIAGASSERT(freep != NULL);
855 CLRBIT(freep, free_bit);
856 #ifdef DEBUG2
857 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
858 obufp->addr, free_bit, free_page);
859 #endif
860 __reclaim_buf(hashp, obufp);
861 }
862
863 /*
864 * We have to know that the key will fit, but the last entry on the page is
865 * an overflow pair, so we need to shift things.
866 */
867 static void
squeeze_key(uint16_t * sp,const DBT * key,const DBT * val)868 squeeze_key(uint16_t *sp, const DBT *key, const DBT *val)
869 {
870 char *p;
871 uint16_t free_space, n, off, pageno;
872 size_t temp;
873
874 p = (char *)(void *)sp;
875 n = sp[0];
876 free_space = FREESPACE(sp);
877 off = OFFSET(sp);
878
879 pageno = sp[n - 1];
880 _DIAGASSERT(off >= key->size);
881 off -= (uint16_t)key->size;
882 sp[n - 1] = off;
883 memmove(p + off, key->data, key->size);
884 _DIAGASSERT(off >= val->size);
885 off -= (uint16_t)val->size;
886 sp[n] = off;
887 memmove(p + off, val->data, val->size);
888 sp[0] = n + 2;
889 sp[n + 1] = pageno;
890 sp[n + 2] = OVFLPAGE;
891 temp = PAIRSIZE(key, val);
892 _DIAGASSERT(free_space >= temp);
893 FREESPACE(sp) = (uint16_t)(free_space - temp);
894 OFFSET(sp) = off;
895 }
896
897 static uint32_t *
fetch_bitmap(HTAB * hashp,int ndx)898 fetch_bitmap(HTAB *hashp, int ndx)
899 {
900 if (ndx >= hashp->nmaps)
901 return (NULL);
902 if ((hashp->mapp[ndx] = malloc((size_t)hashp->BSIZE)) == NULL)
903 return (NULL);
904 if (__get_page(hashp,
905 (char *)(void *)hashp->mapp[ndx], (uint32_t)hashp->BITMAPS[ndx], 0, 1, 1)) {
906 free(hashp->mapp[ndx]);
907 return (NULL);
908 }
909 return (hashp->mapp[ndx]);
910 }
911
912 #ifdef DEBUG4
913 void print_chain(HTAB *, uint32_t);
914 void
print_chain(HTAB * hashp,uint32_t addr)915 print_chain(HTAB *hashp, uint32_t addr)
916 {
917 BUFHEAD *bufp;
918 uint16_t *bp, oaddr;
919
920 (void)fprintf(stderr, "%d ", addr);
921 bufp = __get_buf(hashp, addr, NULL, 0);
922 bp = (uint16_t *)bufp->page;
923 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
924 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
925 oaddr = bp[bp[0] - 1];
926 (void)fprintf(stderr, "%d ", (int)oaddr);
927 bufp = __get_buf(hashp, (uint32_t)oaddr, bufp, 0);
928 bp = (uint16_t *)bufp->page;
929 }
930 (void)fprintf(stderr, "\n");
931 }
932 #endif
933