2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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9 * modification, are permitted provided that the following conditions
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17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
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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
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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
36 * $FreeBSD: src/lib/libc/db/hash/hash.c,v 1.8 2000/01/27 23:06:08 jasone Exp $
37 * $DragonFly: src/lib/libc/db/hash/hash.c,v 1.5 2005/01/31 22:29:09 dillon Exp $
39 * @(#)hash.c 8.9 (Berkeley) 6/16/94
42 #include "namespace.h"
43 #include <sys/param.h>
55 #include "un-namespace.h"
62 static int alloc_segs (HTAB *, int);
63 static int flush_meta (HTAB *);
64 static int hash_access (HTAB *, ACTION, DBT *, DBT *);
65 static int hash_close (DB *);
66 static int hash_delete (const DB *, const DBT *, u_int32_t);
67 static int hash_fd (const DB *);
68 static int hash_get (const DB *, const DBT *, DBT *, u_int32_t);
69 static int hash_put (const DB *, DBT *, const DBT *, u_int32_t);
70 static void *hash_realloc (SEGMENT **, int, int);
71 static int hash_seq (const DB *, DBT *, DBT *, u_int32_t);
72 static int hash_sync (const DB *, u_int32_t);
73 static int hdestroy (HTAB *);
74 static HTAB *init_hash (HTAB *, const char *, HASHINFO *);
75 static int init_htab (HTAB *, int);
76 #if BYTE_ORDER == LITTLE_ENDIAN
77 static void swap_header (HTAB *);
78 static void swap_header_copy (HASHHDR *, HASHHDR *);
81 /* Fast arithmetic, relying on powers of 2, */
82 #define MOD(x, y) ((x) & ((y) - 1))
84 #define RETURN_ERROR(ERR, LOC) { save_errno = ERR; goto LOC; }
91 #ifdef HASH_STATISTICS
92 int hash_accesses, hash_collisions, hash_expansions, hash_overflows;
95 /************************** INTERFACE ROUTINES ***************************/
99 __hash_open(file, flags, mode, info, dflags)
101 int flags, mode, dflags;
102 const HASHINFO *info; /* Special directives for create */
107 int bpages, hdrsize, new_table, nsegs, save_errno;
109 if ((flags & O_ACCMODE) == O_WRONLY) {
114 if (!(hashp = (HTAB *)calloc(1, sizeof(HTAB))))
119 * Even if user wants write only, we need to be able to read
120 * the actual file, so we need to open it read/write. But, the
121 * field in the hashp structure needs to be accurate so that
122 * we can check accesses.
124 hashp->flags = flags;
127 if (!file || (flags & O_TRUNC) ||
128 (stat(file, &statbuf) && (errno == ENOENT))) {
130 errno = 0; /* Just in case someone looks at errno */
134 if ((hashp->fp = _open(file, flags, mode)) == -1)
135 RETURN_ERROR(errno, error0);
137 /* if the .db file is empty, and we had permission to create
138 a new .db file, then reinitialize the database */
139 if ((flags & O_CREAT) &&
140 _fstat(hashp->fp, &statbuf) == 0 && statbuf.st_size == 0)
143 (void)_fcntl(hashp->fp, F_SETFD, 1);
146 if (!(hashp = init_hash(hashp, file, (HASHINFO *)info)))
147 RETURN_ERROR(errno, error1);
149 /* Table already exists */
150 if (info && info->hash)
151 hashp->hash = info->hash;
153 hashp->hash = __default_hash;
155 hdrsize = _read(hashp->fp, &hashp->hdr, sizeof(HASHHDR));
156 #if BYTE_ORDER == LITTLE_ENDIAN
160 RETURN_ERROR(errno, error1);
161 if (hdrsize != sizeof(HASHHDR))
162 RETURN_ERROR(EFTYPE, error1);
163 /* Verify file type, versions and hash function */
164 if (hashp->MAGIC != HASHMAGIC)
165 RETURN_ERROR(EFTYPE, error1);
166 #define OLDHASHVERSION 1
167 if (hashp->VERSION != HASHVERSION &&
168 hashp->VERSION != OLDHASHVERSION)
169 RETURN_ERROR(EFTYPE, error1);
170 if (hashp->hash(CHARKEY, sizeof(CHARKEY)) != hashp->H_CHARKEY)
171 RETURN_ERROR(EFTYPE, error1);
173 * Figure out how many segments we need. Max_Bucket is the
174 * maximum bucket number, so the number of buckets is
177 nsegs = (hashp->MAX_BUCKET + 1 + hashp->SGSIZE - 1) /
180 if (alloc_segs(hashp, nsegs))
182 * If alloc_segs fails, table will have been destroyed
183 * and errno will have been set.
186 /* Read in bitmaps */
187 bpages = (hashp->SPARES[hashp->OVFL_POINT] +
188 (hashp->BSIZE << BYTE_SHIFT) - 1) >>
189 (hashp->BSHIFT + BYTE_SHIFT);
191 hashp->nmaps = bpages;
192 (void)memset(&hashp->mapp[0], 0, bpages * sizeof(u_int32_t *));
195 /* Initialize Buffer Manager */
196 if (info && info->cachesize)
197 __buf_init(hashp, info->cachesize);
199 __buf_init(hashp, DEF_BUFSIZE);
201 hashp->new_file = new_table;
202 hashp->save_file = file && (hashp->flags & O_RDWR);
204 if (!(dbp = (DB *)malloc(sizeof(DB)))) {
210 dbp->internal = hashp;
211 dbp->close = hash_close;
212 dbp->del = hash_delete;
217 dbp->sync = hash_sync;
221 (void)fprintf(stderr,
222 "%s\n%s%x\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%x\n%s%x\n%s%d\n%s%d\n",
224 "TABLE POINTER ", hashp,
225 "BUCKET SIZE ", hashp->BSIZE,
226 "BUCKET SHIFT ", hashp->BSHIFT,
227 "DIRECTORY SIZE ", hashp->DSIZE,
228 "SEGMENT SIZE ", hashp->SGSIZE,
229 "SEGMENT SHIFT ", hashp->SSHIFT,
230 "FILL FACTOR ", hashp->FFACTOR,
231 "MAX BUCKET ", hashp->MAX_BUCKET,
232 "OVFL POINT ", hashp->OVFL_POINT,
233 "LAST FREED ", hashp->LAST_FREED,
234 "HIGH MASK ", hashp->HIGH_MASK,
235 "LOW MASK ", hashp->LOW_MASK,
236 "NSEGS ", hashp->nsegs,
237 "NKEYS ", hashp->NKEYS);
239 #ifdef HASH_STATISTICS
240 hash_overflows = hash_accesses = hash_collisions = hash_expansions = 0;
246 (void)_close(hashp->fp);
264 hashp = (HTAB *)dbp->internal;
265 retval = hdestroy(hashp);
279 hashp = (HTAB *)dbp->internal;
280 if (hashp->fp == -1) {
287 /************************** LOCAL CREATION ROUTINES **********************/
289 init_hash(hashp, file, info)
299 hashp->LORDER = BYTE_ORDER;
300 hashp->BSIZE = DEF_BUCKET_SIZE;
301 hashp->BSHIFT = DEF_BUCKET_SHIFT;
302 hashp->SGSIZE = DEF_SEGSIZE;
303 hashp->SSHIFT = DEF_SEGSIZE_SHIFT;
304 hashp->DSIZE = DEF_DIRSIZE;
305 hashp->FFACTOR = DEF_FFACTOR;
306 hashp->hash = __default_hash;
307 memset(hashp->SPARES, 0, sizeof(hashp->SPARES));
308 memset(hashp->BITMAPS, 0, sizeof (hashp->BITMAPS));
310 /* Fix bucket size to be optimal for file system */
312 if (stat(file, &statbuf))
314 hashp->BSIZE = statbuf.st_blksize;
315 hashp->BSHIFT = __log2(hashp->BSIZE);
320 /* Round pagesize up to power of 2 */
321 hashp->BSHIFT = __log2(info->bsize);
322 hashp->BSIZE = 1 << hashp->BSHIFT;
323 if (hashp->BSIZE > MAX_BSIZE) {
329 hashp->FFACTOR = info->ffactor;
331 hashp->hash = info->hash;
335 if (info->lorder != BIG_ENDIAN &&
336 info->lorder != LITTLE_ENDIAN) {
340 hashp->LORDER = info->lorder;
343 /* init_htab should destroy the table and set errno if it fails */
344 if (init_htab(hashp, nelem))
350 * This calls alloc_segs which may run out of memory. Alloc_segs will destroy
351 * the table and set errno, so we just pass the error information along.
353 * Returns 0 on No Error
356 init_htab(hashp, nelem)
364 * Divide number of elements by the fill factor and determine a
365 * desired number of buckets. Allocate space for the next greater
366 * power of two number of buckets.
368 nelem = (nelem - 1) / hashp->FFACTOR + 1;
370 l2 = __log2(MAX(nelem, 2));
373 hashp->SPARES[l2] = l2 + 1;
374 hashp->SPARES[l2 + 1] = l2 + 1;
375 hashp->OVFL_POINT = l2;
376 hashp->LAST_FREED = 2;
378 /* First bitmap page is at: splitpoint l2 page offset 1 */
379 if (__ibitmap(hashp, OADDR_OF(l2, 1), l2 + 1, 0))
382 hashp->MAX_BUCKET = hashp->LOW_MASK = nbuckets - 1;
383 hashp->HIGH_MASK = (nbuckets << 1) - 1;
384 hashp->HDRPAGES = ((MAX(sizeof(HASHHDR), MINHDRSIZE) - 1) >>
387 nsegs = (nbuckets - 1) / hashp->SGSIZE + 1;
388 nsegs = 1 << __log2(nsegs);
390 if (nsegs > hashp->DSIZE)
391 hashp->DSIZE = nsegs;
392 return (alloc_segs(hashp, nsegs));
395 /********************** DESTROY/CLOSE ROUTINES ************************/
398 * Flushes any changes to the file if necessary and destroys the hashp
399 * structure, freeing all allocated space.
409 #ifdef HASH_STATISTICS
410 (void)fprintf(stderr, "hdestroy: accesses %ld collisions %ld\n",
411 hash_accesses, hash_collisions);
412 (void)fprintf(stderr, "hdestroy: expansions %ld\n",
414 (void)fprintf(stderr, "hdestroy: overflows %ld\n",
416 (void)fprintf(stderr, "keys %ld maxp %d segmentcount %d\n",
417 hashp->NKEYS, hashp->MAX_BUCKET, hashp->nsegs);
419 for (i = 0; i < NCACHED; i++)
420 (void)fprintf(stderr,
421 "spares[%d] = %d\n", i, hashp->SPARES[i]);
424 * Call on buffer manager to free buffers, and if required,
425 * write them to disk.
427 if (__buf_free(hashp, 1, hashp->save_file))
430 free(*hashp->dir); /* Free initial segments */
431 /* Free extra segments */
432 while (hashp->exsegs--)
433 free(hashp->dir[--hashp->nsegs]);
436 if (flush_meta(hashp) && !save_errno)
439 for (i = 0; i < hashp->nmaps; i++)
441 free(hashp->mapp[i]);
444 (void)_close(hashp->fp);
455 * Write modified pages to disk
462 hash_sync(dbp, flags)
476 hashp = (HTAB *)dbp->internal;
477 if (!hashp->save_file)
479 if (__buf_free(hashp, 0, 1) || flush_meta(hashp))
488 * -1 indicates that errno should be set
495 #if BYTE_ORDER == LITTLE_ENDIAN
500 if (!hashp->save_file)
502 hashp->MAGIC = HASHMAGIC;
503 hashp->VERSION = HASHVERSION;
504 hashp->H_CHARKEY = hashp->hash(CHARKEY, sizeof(CHARKEY));
508 #if BYTE_ORDER == LITTLE_ENDIAN
510 swap_header_copy(&hashp->hdr, whdrp);
512 if ((lseek(fp, (off_t)0, SEEK_SET) == -1) ||
513 ((wsize = _write(fp, whdrp, sizeof(HASHHDR))) == -1))
516 if (wsize != sizeof(HASHHDR)) {
518 hashp->error = errno;
521 for (i = 0; i < NCACHED; i++)
523 if (__put_page(hashp, (char *)hashp->mapp[i],
524 hashp->BITMAPS[i], 0, 1))
529 /*******************************SEARCH ROUTINES *****************************/
531 * All the access routines return
535 * 1 to indicate an external ERROR (i.e. key not found, etc)
536 * -1 to indicate an internal ERROR (i.e. out of memory, etc)
539 hash_get(dbp, key, data, flag)
547 hashp = (HTAB *)dbp->internal;
549 hashp->error = EINVAL;
553 return (hash_access(hashp, HASH_GET, (DBT *)key, data));
557 hash_put(dbp, key, data, flag)
565 hashp = (HTAB *)dbp->internal;
566 if (flag && flag != R_NOOVERWRITE) {
567 hashp->error = errno = EINVAL;
570 if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
571 hashp->error = errno = EPERM;
574 return (hash_access(hashp, flag == R_NOOVERWRITE ?
575 HASH_PUTNEW : HASH_PUT, (DBT *)key, (DBT *)data));
579 hash_delete(dbp, key, flag)
582 u_int32_t flag; /* Ignored */
586 hashp = (HTAB *)dbp->internal;
587 if (flag && flag != R_CURSOR) {
588 hashp->error = errno = EINVAL;
591 if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
592 hashp->error = errno = EPERM;
595 return (hash_access(hashp, HASH_DELETE, (DBT *)key, NULL));
599 * Assume that hashp has been set in wrapper routine.
602 hash_access(hashp, action, key, val)
608 BUFHEAD *bufp, *save_bufp;
610 int n, ndx, off, size;
614 #ifdef HASH_STATISTICS
620 kp = (char *)key->data;
621 rbufp = __get_buf(hashp, __call_hash(hashp, kp, size), NULL, 0);
626 /* Pin the bucket chain */
627 rbufp->flags |= BUF_PIN;
628 for (bp = (u_int16_t *)rbufp->page, n = *bp++, ndx = 1; ndx < n;)
629 if (bp[1] >= REAL_KEY) {
630 /* Real key/data pair */
631 if (size == off - *bp &&
632 memcmp(kp, rbufp->page + *bp, size) == 0)
635 #ifdef HASH_STATISTICS
640 } else if (bp[1] == OVFLPAGE) {
641 rbufp = __get_buf(hashp, *bp, rbufp, 0);
643 save_bufp->flags &= ~BUF_PIN;
647 bp = (u_int16_t *)rbufp->page;
651 } else if (bp[1] < REAL_KEY) {
653 __find_bigpair(hashp, rbufp, ndx, kp, size)) > 0)
658 __find_last_page(hashp, &bufp))) {
663 rbufp = __get_buf(hashp, pageno, bufp, 0);
665 save_bufp->flags &= ~BUF_PIN;
669 bp = (u_int16_t *)rbufp->page;
674 save_bufp->flags &= ~BUF_PIN;
683 if (__addel(hashp, rbufp, key, val)) {
684 save_bufp->flags &= ~BUF_PIN;
687 save_bufp->flags &= ~BUF_PIN;
693 save_bufp->flags &= ~BUF_PIN;
700 save_bufp->flags &= ~BUF_PIN;
703 bp = (u_int16_t *)rbufp->page;
704 if (bp[ndx + 1] < REAL_KEY) {
705 if (__big_return(hashp, rbufp, ndx, val, 0))
708 val->data = (u_char *)rbufp->page + (int)bp[ndx + 1];
709 val->size = bp[ndx] - bp[ndx + 1];
713 if ((__delpair(hashp, rbufp, ndx)) ||
714 (__addel(hashp, rbufp, key, val))) {
715 save_bufp->flags &= ~BUF_PIN;
720 if (__delpair(hashp, rbufp, ndx))
726 save_bufp->flags &= ~BUF_PIN;
731 hash_seq(dbp, key, data, flag)
741 hashp = (HTAB *)dbp->internal;
742 if (flag && flag != R_FIRST && flag != R_NEXT) {
743 hashp->error = errno = EINVAL;
746 #ifdef HASH_STATISTICS
749 if ((hashp->cbucket < 0) || (flag == R_FIRST)) {
755 for (bp = NULL; !bp || !bp[0]; ) {
756 if (!(bufp = hashp->cpage)) {
757 for (bucket = hashp->cbucket;
758 bucket <= hashp->MAX_BUCKET;
759 bucket++, hashp->cndx = 1) {
760 bufp = __get_buf(hashp, bucket, NULL, 0);
764 bp = (u_int16_t *)bufp->page;
768 hashp->cbucket = bucket;
769 if (hashp->cbucket > hashp->MAX_BUCKET) {
774 bp = (u_int16_t *)hashp->cpage->page;
780 while (bp[hashp->cndx + 1] == OVFLPAGE) {
781 bufp = hashp->cpage =
782 __get_buf(hashp, bp[hashp->cndx], bufp, 0);
785 bp = (u_int16_t *)(bufp->page);
794 if (bp[ndx + 1] < REAL_KEY) {
795 if (__big_keydata(hashp, bufp, key, data, 1))
798 key->data = (u_char *)hashp->cpage->page + bp[ndx];
799 key->size = (ndx > 1 ? bp[ndx - 1] : hashp->BSIZE) - bp[ndx];
800 data->data = (u_char *)hashp->cpage->page + bp[ndx + 1];
801 data->size = bp[ndx] - bp[ndx + 1];
813 /********************************* UTILITIES ************************/
821 __expand_table(hashp)
824 u_int32_t old_bucket, new_bucket;
825 int dirsize, new_segnum, spare_ndx;
827 #ifdef HASH_STATISTICS
830 new_bucket = ++hashp->MAX_BUCKET;
831 old_bucket = (hashp->MAX_BUCKET & hashp->LOW_MASK);
833 new_segnum = new_bucket >> hashp->SSHIFT;
835 /* Check if we need a new segment */
836 if (new_segnum >= hashp->nsegs) {
837 /* Check if we need to expand directory */
838 if (new_segnum >= hashp->DSIZE) {
839 /* Reallocate directory */
840 dirsize = hashp->DSIZE * sizeof(SEGMENT *);
841 if (!hash_realloc(&hashp->dir, dirsize, dirsize << 1))
843 hashp->DSIZE = dirsize << 1;
845 if ((hashp->dir[new_segnum] =
846 (SEGMENT)calloc(hashp->SGSIZE, sizeof(SEGMENT))) == NULL)
852 * If the split point is increasing (MAX_BUCKET's log base 2
853 * * increases), we need to copy the current contents of the spare
854 * split bucket to the next bucket.
856 spare_ndx = __log2(hashp->MAX_BUCKET + 1);
857 if (spare_ndx > hashp->OVFL_POINT) {
858 hashp->SPARES[spare_ndx] = hashp->SPARES[hashp->OVFL_POINT];
859 hashp->OVFL_POINT = spare_ndx;
862 if (new_bucket > hashp->HIGH_MASK) {
863 /* Starting a new doubling */
864 hashp->LOW_MASK = hashp->HIGH_MASK;
865 hashp->HIGH_MASK = new_bucket | hashp->LOW_MASK;
867 /* Relocate records to the new bucket */
868 return (__split_page(hashp, old_bucket, new_bucket));
872 * If realloc guarantees that the pointer is not destroyed if the realloc
873 * fails, then this routine can go away.
876 hash_realloc(p_ptr, oldsize, newsize)
878 int oldsize, newsize;
882 if ( (p = malloc(newsize)) ) {
883 memmove(p, *p_ptr, oldsize);
884 memset((char *)p + oldsize, 0, newsize - oldsize);
892 __call_hash(hashp, k, len)
899 n = hashp->hash(k, len);
900 bucket = n & hashp->HIGH_MASK;
901 if (bucket > hashp->MAX_BUCKET)
902 bucket = bucket & hashp->LOW_MASK;
907 * Allocate segment table. On error, destroy the table and set errno.
909 * Returns 0 on success
912 alloc_segs(hashp, nsegs)
922 (SEGMENT *)calloc(hashp->DSIZE, sizeof(SEGMENT *))) == NULL) {
924 (void)hdestroy(hashp);
928 /* Allocate segments */
930 (SEGMENT)calloc(nsegs << hashp->SSHIFT, sizeof(SEGMENT))) == NULL) {
932 (void)hdestroy(hashp);
936 for (i = 0; i < nsegs; i++, hashp->nsegs++)
937 hashp->dir[i] = &store[i << hashp->SSHIFT];
941 #if BYTE_ORDER == LITTLE_ENDIAN
943 * Hashp->hdr needs to be byteswapped.
946 swap_header_copy(srcp, destp)
947 HASHHDR *srcp, *destp;
951 P_32_COPY(srcp->magic, destp->magic);
952 P_32_COPY(srcp->version, destp->version);
953 P_32_COPY(srcp->lorder, destp->lorder);
954 P_32_COPY(srcp->bsize, destp->bsize);
955 P_32_COPY(srcp->bshift, destp->bshift);
956 P_32_COPY(srcp->dsize, destp->dsize);
957 P_32_COPY(srcp->ssize, destp->ssize);
958 P_32_COPY(srcp->sshift, destp->sshift);
959 P_32_COPY(srcp->ovfl_point, destp->ovfl_point);
960 P_32_COPY(srcp->last_freed, destp->last_freed);
961 P_32_COPY(srcp->max_bucket, destp->max_bucket);
962 P_32_COPY(srcp->high_mask, destp->high_mask);
963 P_32_COPY(srcp->low_mask, destp->low_mask);
964 P_32_COPY(srcp->ffactor, destp->ffactor);
965 P_32_COPY(srcp->nkeys, destp->nkeys);
966 P_32_COPY(srcp->hdrpages, destp->hdrpages);
967 P_32_COPY(srcp->h_charkey, destp->h_charkey);
968 for (i = 0; i < NCACHED; i++) {
969 P_32_COPY(srcp->spares[i], destp->spares[i]);
970 P_16_COPY(srcp->bitmaps[i], destp->bitmaps[i]);
983 M_32_SWAP(hdrp->magic);
984 M_32_SWAP(hdrp->version);
985 M_32_SWAP(hdrp->lorder);
986 M_32_SWAP(hdrp->bsize);
987 M_32_SWAP(hdrp->bshift);
988 M_32_SWAP(hdrp->dsize);
989 M_32_SWAP(hdrp->ssize);
990 M_32_SWAP(hdrp->sshift);
991 M_32_SWAP(hdrp->ovfl_point);
992 M_32_SWAP(hdrp->last_freed);
993 M_32_SWAP(hdrp->max_bucket);
994 M_32_SWAP(hdrp->high_mask);
995 M_32_SWAP(hdrp->low_mask);
996 M_32_SWAP(hdrp->ffactor);
997 M_32_SWAP(hdrp->nkeys);
998 M_32_SWAP(hdrp->hdrpages);
999 M_32_SWAP(hdrp->h_charkey);
1000 for (i = 0; i < NCACHED; i++) {
1001 M_32_SWAP(hdrp->spares[i]);
1002 M_16_SWAP(hdrp->bitmaps[i]);