hash.c revision 1.2
1 /*- 2 * Copyright (c) 1990, 1993 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) 38 /*static char sccsid[] = "from: @(#)hash.c 8.1 (Berkeley) 6/6/93";*/ 39 static char rcsid[] = "$Id: hash.c,v 1.2 1993/08/01 18:43:32 mycroft Exp $"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <sys/param.h> 43 #include <sys/stat.h> 44 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 #ifdef DEBUG 52 #include <assert.h> 53 #endif 54 55 #include <db.h> 56 #include "hash.h" 57 #include "page.h" 58 #include "extern.h" 59 60 static int alloc_segs __P((HTAB *, int)); 61 static int flush_meta __P((HTAB *)); 62 static int hash_access __P((HTAB *, ACTION, DBT *, DBT *)); 63 static int hash_close __P((DB *)); 64 static int hash_delete __P((const DB *, const DBT *, u_int)); 65 static int hash_fd __P((const DB *)); 66 static int hash_get __P((const DB *, const DBT *, DBT *, u_int)); 67 static int hash_put __P((const DB *, DBT *, const DBT *, u_int)); 68 static void *hash_realloc __P((SEGMENT **, int, int)); 69 static int hash_seq __P((const DB *, DBT *, DBT *, u_int)); 70 static int hash_sync __P((const DB *, u_int)); 71 static int hdestroy __P((HTAB *)); 72 static HTAB *init_hash __P((HTAB *, const char *, HASHINFO *)); 73 static int init_htab __P((HTAB *, int)); 74 #if BYTE_ORDER == LITTLE_ENDIAN 75 static void swap_header __P((HTAB *)); 76 static void swap_header_copy __P((HASHHDR *, HASHHDR *)); 77 #endif 78 79 /* Fast arithmetic, relying on powers of 2, */ 80 #define MOD(x, y) ((x) & ((y) - 1)) 81 82 #define RETURN_ERROR(ERR, LOC) { save_errno = ERR; goto LOC; } 83 84 /* Return values */ 85 #define SUCCESS (0) 86 #define ERROR (-1) 87 #define ABNORMAL (1) 88 89 #ifdef HASH_STATISTICS 90 long hash_accesses, hash_collisions, hash_expansions, hash_overflows; 91 #endif 92 93 /************************** INTERFACE ROUTINES ***************************/ 94 /* OPEN/CLOSE */ 95 96 extern DB * 97 __hash_open(file, flags, mode, info) 98 const char *file; 99 int flags, mode; 100 const HASHINFO *info; /* Special directives for create */ 101 { 102 HTAB *hashp; 103 struct stat statbuf; 104 DB *dbp; 105 int bpages, hdrsize, new_table, nsegs, save_errno; 106 107 if ((flags & O_ACCMODE) == O_WRONLY) { 108 errno = EINVAL; 109 return (NULL); 110 } 111 112 if (!(hashp = calloc(1, sizeof(HTAB)))) 113 return (NULL); 114 hashp->fp = -1; 115 /* 116 * Select flags relevant to us. Even if user wants write only, we need 117 * to be able to read the actual file, so we need to open it read/write. 118 * But, the field in the hashp structure needs to be accurate so that 119 * we can check accesses. 120 */ 121 hashp->flags = flags = flags & __USE_OPEN_FLAGS; 122 123 new_table = 0; 124 if (!file || (flags & O_TRUNC) || 125 (stat(file, &statbuf) && (errno == ENOENT))) { 126 if (errno == ENOENT) 127 errno = 0; /* Just in case someone looks at errno */ 128 new_table = 1; 129 } 130 if (file) { 131 if ((hashp->fp = open(file, flags, mode)) == -1) 132 RETURN_ERROR(errno, error0); 133 (void)fcntl(hashp->fp, F_SETFD, 1); 134 } 135 if (new_table) { 136 if (!(hashp = init_hash(hashp, file, (HASHINFO *)info))) 137 RETURN_ERROR(errno, error1); 138 } else { 139 /* Table already exists */ 140 if (info && info->hash) 141 hashp->hash = info->hash; 142 else 143 hashp->hash = __default_hash; 144 145 hdrsize = read(hashp->fp, &hashp->hdr, sizeof(HASHHDR)); 146 #if BYTE_ORDER == LITTLE_ENDIAN 147 swap_header(hashp); 148 #endif 149 if (hdrsize == -1) 150 RETURN_ERROR(errno, error1); 151 if (hdrsize != sizeof(HASHHDR)) 152 RETURN_ERROR(EFTYPE, error1); 153 /* Verify file type, versions and hash function */ 154 if (hashp->MAGIC != HASHMAGIC) 155 RETURN_ERROR(EFTYPE, error1); 156 if (hashp->VERSION != HASHVERSION) 157 RETURN_ERROR(EFTYPE, error1); 158 if (hashp->hash(CHARKEY, sizeof(CHARKEY)) != hashp->H_CHARKEY) 159 RETURN_ERROR(EFTYPE, error1); 160 /* 161 * Figure out how many segments we need. Max_Bucket is the 162 * maximum bucket number, so the number of buckets is 163 * max_bucket + 1. 164 */ 165 nsegs = (hashp->MAX_BUCKET + 1 + hashp->SGSIZE - 1) / 166 hashp->SGSIZE; 167 hashp->nsegs = 0; 168 if (alloc_segs(hashp, nsegs)) 169 /* 170 * If alloc_segs fails, table will have been destroyed 171 * and errno will have been set. 172 */ 173 return (NULL); 174 /* Read in bitmaps */ 175 bpages = (hashp->SPARES[hashp->OVFL_POINT] + 176 (hashp->BSIZE << BYTE_SHIFT) - 1) >> 177 (hashp->BSHIFT + BYTE_SHIFT); 178 179 hashp->nmaps = bpages; 180 (void)memset(&hashp->mapp[0], 0, bpages * sizeof(u_long *)); 181 } 182 183 /* Initialize Buffer Manager */ 184 if (info && info->cachesize) 185 __buf_init(hashp, info->cachesize); 186 else 187 __buf_init(hashp, DEF_BUFSIZE); 188 189 hashp->new_file = new_table; 190 hashp->save_file = file && (hashp->flags & O_RDWR); 191 hashp->cbucket = -1; 192 if (!(dbp = malloc(sizeof(DB)))) { 193 save_errno = errno; 194 hdestroy(hashp); 195 errno = save_errno; 196 return (NULL); 197 } 198 dbp->internal = hashp; 199 dbp->close = hash_close; 200 dbp->del = hash_delete; 201 dbp->fd = hash_fd; 202 dbp->get = hash_get; 203 dbp->put = hash_put; 204 dbp->seq = hash_seq; 205 dbp->sync = hash_sync; 206 dbp->type = DB_HASH; 207 208 #ifdef DEBUG 209 (void)fprintf(stderr, 210 "%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", 211 "init_htab:", 212 "TABLE POINTER ", hashp, 213 "BUCKET SIZE ", hashp->BSIZE, 214 "BUCKET SHIFT ", hashp->BSHIFT, 215 "DIRECTORY SIZE ", hashp->DSIZE, 216 "SEGMENT SIZE ", hashp->SGSIZE, 217 "SEGMENT SHIFT ", hashp->SSHIFT, 218 "FILL FACTOR ", hashp->FFACTOR, 219 "MAX BUCKET ", hashp->MAX_BUCKET, 220 "OVFL POINT ", hashp->OVFL_POINT, 221 "LAST FREED ", hashp->LAST_FREED, 222 "HIGH MASK ", hashp->HIGH_MASK, 223 "LOW MASK ", hashp->LOW_MASK, 224 "NSEGS ", hashp->nsegs, 225 "NKEYS ", hashp->NKEYS); 226 #endif 227 #ifdef HASH_STATISTICS 228 hash_overflows = hash_accesses = hash_collisions = hash_expansions = 0; 229 #endif 230 return (dbp); 231 232 error1: 233 if (hashp != NULL) 234 (void)close(hashp->fp); 235 236 error0: 237 free(hashp); 238 errno = save_errno; 239 return (NULL); 240 } 241 242 static int 243 hash_close(dbp) 244 DB *dbp; 245 { 246 HTAB *hashp; 247 int retval; 248 249 if (!dbp) 250 return (ERROR); 251 252 hashp = (HTAB *)dbp->internal; 253 retval = hdestroy(hashp); 254 free(dbp); 255 return (retval); 256 } 257 258 static int 259 hash_fd(dbp) 260 const DB *dbp; 261 { 262 HTAB *hashp; 263 264 if (!dbp) 265 return (ERROR); 266 267 hashp = (HTAB *)dbp->internal; 268 if (hashp->fp == -1) { 269 errno = ENOENT; 270 return (-1); 271 } 272 return (hashp->fp); 273 } 274 275 /************************** LOCAL CREATION ROUTINES **********************/ 276 static HTAB * 277 init_hash(hashp, file, info) 278 HTAB *hashp; 279 const char *file; 280 HASHINFO *info; 281 { 282 struct stat statbuf; 283 int nelem; 284 285 nelem = 1; 286 hashp->NKEYS = 0; 287 hashp->LORDER = BYTE_ORDER; 288 hashp->BSIZE = DEF_BUCKET_SIZE; 289 hashp->BSHIFT = DEF_BUCKET_SHIFT; 290 hashp->SGSIZE = DEF_SEGSIZE; 291 hashp->SSHIFT = DEF_SEGSIZE_SHIFT; 292 hashp->DSIZE = DEF_DIRSIZE; 293 hashp->FFACTOR = DEF_FFACTOR; 294 hashp->hash = __default_hash; 295 memset(hashp->SPARES, 0, sizeof(hashp->SPARES)); 296 memset(hashp->BITMAPS, 0, sizeof (hashp->BITMAPS)); 297 298 /* Fix bucket size to be optimal for file system */ 299 if (file != NULL) { 300 if (stat(file, &statbuf)) 301 return (NULL); 302 hashp->BSIZE = statbuf.st_blksize; 303 hashp->BSHIFT = __log2(hashp->BSIZE); 304 } 305 306 if (info) { 307 if (info->bsize) { 308 /* Round pagesize up to power of 2 */ 309 hashp->BSHIFT = __log2(info->bsize); 310 hashp->BSIZE = 1 << hashp->BSHIFT; 311 if (hashp->BSIZE > MAX_BSIZE) { 312 errno = EINVAL; 313 return (NULL); 314 } 315 } 316 if (info->ffactor) 317 hashp->FFACTOR = info->ffactor; 318 if (info->hash) 319 hashp->hash = info->hash; 320 if (info->nelem) 321 nelem = info->nelem; 322 if (info->lorder) { 323 if (info->lorder != BIG_ENDIAN && 324 info->lorder != LITTLE_ENDIAN) { 325 errno = EINVAL; 326 return (NULL); 327 } 328 hashp->LORDER = info->lorder; 329 } 330 } 331 /* init_htab should destroy the table and set errno if it fails */ 332 if (init_htab(hashp, nelem)) 333 return (NULL); 334 else 335 return (hashp); 336 } 337 /* 338 * This calls alloc_segs which may run out of memory. Alloc_segs will destroy 339 * the table and set errno, so we just pass the error information along. 340 * 341 * Returns 0 on No Error 342 */ 343 static int 344 init_htab(hashp, nelem) 345 HTAB *hashp; 346 int nelem; 347 { 348 register int nbuckets, nsegs; 349 int l2; 350 351 /* 352 * Divide number of elements by the fill factor and determine a 353 * desired number of buckets. Allocate space for the next greater 354 * power of two number of buckets. 355 */ 356 nelem = (nelem - 1) / hashp->FFACTOR + 1; 357 358 l2 = __log2(MAX(nelem, 2)); 359 nbuckets = 1 << l2; 360 361 hashp->SPARES[l2] = l2 + 1; 362 hashp->SPARES[l2 + 1] = l2 + 1; 363 hashp->OVFL_POINT = l2; 364 hashp->LAST_FREED = 2; 365 366 /* First bitmap page is at: splitpoint l2 page offset 1 */ 367 if (__init_bitmap(hashp, OADDR_OF(l2, 1), l2 + 1, 0)) 368 return (-1); 369 370 hashp->MAX_BUCKET = hashp->LOW_MASK = nbuckets - 1; 371 hashp->HIGH_MASK = (nbuckets << 1) - 1; 372 hashp->HDRPAGES = ((MAX(sizeof(HASHHDR), MINHDRSIZE) - 1) >> 373 hashp->BSHIFT) + 1; 374 375 nsegs = (nbuckets - 1) / hashp->SGSIZE + 1; 376 nsegs = 1 << __log2(nsegs); 377 378 if (nsegs > hashp->DSIZE) 379 hashp->DSIZE = nsegs; 380 return (alloc_segs(hashp, nsegs)); 381 } 382 383 /********************** DESTROY/CLOSE ROUTINES ************************/ 384 385 /* 386 * Flushes any changes to the file if necessary and destroys the hashp 387 * structure, freeing all allocated space. 388 */ 389 static int 390 hdestroy(hashp) 391 HTAB *hashp; 392 { 393 int i, save_errno; 394 395 save_errno = 0; 396 397 #ifdef HASH_STATISTICS 398 (void)fprintf(stderr, "hdestroy: accesses %ld collisions %ld\n", 399 hash_accesses, hash_collisions); 400 (void)fprintf(stderr, "hdestroy: expansions %ld\n", 401 hash_expansions); 402 (void)fprintf(stderr, "hdestroy: overflows %ld\n", 403 hash_overflows); 404 (void)fprintf(stderr, "keys %ld maxp %d segmentcount %d\n", 405 hashp->NKEYS, hashp->MAX_BUCKET, hashp->nsegs); 406 407 for (i = 0; i < NCACHED; i++) 408 (void)fprintf(stderr, 409 "spares[%d] = %d\n", i, hashp->SPARES[i]); 410 #endif 411 /* 412 * Call on buffer manager to free buffers, and if required, 413 * write them to disk. 414 */ 415 if (__buf_free(hashp, 1, hashp->save_file)) 416 save_errno = errno; 417 if (hashp->dir) { 418 free(*hashp->dir); /* Free initial segments */ 419 /* Free extra segments */ 420 while (hashp->exsegs--) 421 free(hashp->dir[--hashp->nsegs]); 422 free(hashp->dir); 423 } 424 if (flush_meta(hashp) && !save_errno) 425 save_errno = errno; 426 /* Free Bigmaps */ 427 for (i = 0; i < hashp->nmaps; i++) 428 if (hashp->mapp[i]) 429 free(hashp->mapp[i]); 430 431 if (hashp->fp != -1) 432 (void)close(hashp->fp); 433 434 if (save_errno) { 435 errno = save_errno; 436 return (ERROR); 437 } 438 return (SUCCESS); 439 } 440 /* 441 * Write modified pages to disk 442 * 443 * Returns: 444 * 0 == OK 445 * -1 ERROR 446 */ 447 static int 448 hash_sync(dbp, flags) 449 const DB *dbp; 450 u_int flags; 451 { 452 HTAB *hashp; 453 454 if (flags != 0) { 455 errno = EINVAL; 456 return (ERROR); 457 } 458 459 if (!dbp) 460 return (ERROR); 461 462 hashp = (HTAB *)dbp->internal; 463 if (!hashp->save_file) 464 return (0); 465 if (__buf_free(hashp, 0, 1) || flush_meta(hashp)) 466 return (ERROR); 467 hashp->new_file = 0; 468 return (0); 469 } 470 471 /* 472 * Returns: 473 * 0 == OK 474 * -1 indicates that errno should be set 475 */ 476 static int 477 flush_meta(hashp) 478 HTAB *hashp; 479 { 480 HASHHDR *whdrp; 481 #if BYTE_ORDER == LITTLE_ENDIAN 482 HASHHDR whdr; 483 #endif 484 int fp, i, wsize; 485 486 if (!hashp->save_file) 487 return (0); 488 hashp->MAGIC = HASHMAGIC; 489 hashp->VERSION = HASHVERSION; 490 hashp->H_CHARKEY = hashp->hash(CHARKEY, sizeof(CHARKEY)); 491 492 fp = hashp->fp; 493 whdrp = &hashp->hdr; 494 #if BYTE_ORDER == LITTLE_ENDIAN 495 whdrp = &whdr; 496 swap_header_copy(&hashp->hdr, whdrp); 497 #endif 498 if ((lseek(fp, (off_t)0, SEEK_SET) == -1) || 499 ((wsize = write(fp, whdrp, sizeof(HASHHDR))) == -1)) 500 return (-1); 501 else 502 if (wsize != sizeof(HASHHDR)) { 503 errno = EFTYPE; 504 hashp->errno = errno; 505 return (-1); 506 } 507 for (i = 0; i < NCACHED; i++) 508 if (hashp->mapp[i]) 509 if (__put_page(hashp, (char *)hashp->mapp[i], 510 hashp->BITMAPS[i], 0, 1)) 511 return (-1); 512 return (0); 513 } 514 515 /*******************************SEARCH ROUTINES *****************************/ 516 /* 517 * All the access routines return 518 * 519 * Returns: 520 * 0 on SUCCESS 521 * 1 to indicate an external ERROR (i.e. key not found, etc) 522 * -1 to indicate an internal ERROR (i.e. out of memory, etc) 523 */ 524 static int 525 hash_get(dbp, key, data, flag) 526 const DB *dbp; 527 const DBT *key; 528 DBT *data; 529 u_int flag; 530 { 531 HTAB *hashp; 532 533 hashp = (HTAB *)dbp->internal; 534 if (flag) { 535 hashp->errno = errno = EINVAL; 536 return (ERROR); 537 } 538 return (hash_access(hashp, HASH_GET, (DBT *)key, data)); 539 } 540 541 static int 542 hash_put(dbp, key, data, flag) 543 const DB *dbp; 544 DBT *key; 545 const DBT *data; 546 u_int flag; 547 { 548 HTAB *hashp; 549 550 hashp = (HTAB *)dbp->internal; 551 if (flag && flag != R_NOOVERWRITE) { 552 hashp->errno = errno = EINVAL; 553 return (ERROR); 554 } 555 if ((hashp->flags & O_ACCMODE) == O_RDONLY) { 556 hashp->errno = errno = EPERM; 557 return (ERROR); 558 } 559 return (hash_access(hashp, flag == R_NOOVERWRITE ? 560 HASH_PUTNEW : HASH_PUT, (DBT *)key, (DBT *)data)); 561 } 562 563 static int 564 hash_delete(dbp, key, flag) 565 const DB *dbp; 566 const DBT *key; 567 u_int flag; /* Ignored */ 568 { 569 HTAB *hashp; 570 571 hashp = (HTAB *)dbp->internal; 572 if (flag && flag != R_CURSOR) { 573 hashp->errno = errno = EINVAL; 574 return (ERROR); 575 } 576 if ((hashp->flags & O_ACCMODE) == O_RDONLY) { 577 hashp->errno = errno = EPERM; 578 return (ERROR); 579 } 580 return (hash_access(hashp, HASH_DELETE, (DBT *)key, NULL)); 581 } 582 583 /* 584 * Assume that hashp has been set in wrapper routine. 585 */ 586 static int 587 hash_access(hashp, action, key, val) 588 HTAB *hashp; 589 ACTION action; 590 DBT *key, *val; 591 { 592 register BUFHEAD *rbufp; 593 BUFHEAD *bufp, *save_bufp; 594 register u_short *bp; 595 register int n, ndx, off, size; 596 register char *kp; 597 u_short pageno; 598 599 #ifdef HASH_STATISTICS 600 hash_accesses++; 601 #endif 602 603 off = hashp->BSIZE; 604 size = key->size; 605 kp = (char *)key->data; 606 rbufp = __get_buf(hashp, __call_hash(hashp, kp, size), NULL, 0); 607 if (!rbufp) 608 return (ERROR); 609 save_bufp = rbufp; 610 611 /* Pin the bucket chain */ 612 rbufp->flags |= BUF_PIN; 613 for (bp = (u_short *)rbufp->page, n = *bp++, ndx = 1; ndx < n;) 614 if (bp[1] >= REAL_KEY) { 615 /* Real key/data pair */ 616 if (size == off - *bp && 617 memcmp(kp, rbufp->page + *bp, size) == 0) 618 goto found; 619 off = bp[1]; 620 #ifdef HASH_STATISTICS 621 hash_collisions++; 622 #endif 623 bp += 2; 624 ndx += 2; 625 } else if (bp[1] == OVFLPAGE) { 626 rbufp = __get_buf(hashp, *bp, rbufp, 0); 627 if (!rbufp) { 628 save_bufp->flags &= ~BUF_PIN; 629 return (ERROR); 630 } 631 /* FOR LOOP INIT */ 632 bp = (u_short *)rbufp->page; 633 n = *bp++; 634 ndx = 1; 635 off = hashp->BSIZE; 636 } else if (bp[1] < REAL_KEY) { 637 if ((ndx = 638 __find_bigpair(hashp, rbufp, ndx, kp, size)) > 0) 639 goto found; 640 if (ndx == -2) { 641 bufp = rbufp; 642 if (!(pageno = 643 __find_last_page(hashp, &bufp))) { 644 ndx = 0; 645 rbufp = bufp; 646 break; /* FOR */ 647 } 648 rbufp = __get_buf(hashp, pageno, bufp, 0); 649 if (!rbufp) { 650 save_bufp->flags &= ~BUF_PIN; 651 return (ERROR); 652 } 653 /* FOR LOOP INIT */ 654 bp = (u_short *)rbufp->page; 655 n = *bp++; 656 ndx = 1; 657 off = hashp->BSIZE; 658 } else { 659 save_bufp->flags &= ~BUF_PIN; 660 return (ERROR); 661 } 662 } 663 664 /* Not found */ 665 switch (action) { 666 case HASH_PUT: 667 case HASH_PUTNEW: 668 if (__addel(hashp, rbufp, key, val)) { 669 save_bufp->flags &= ~BUF_PIN; 670 return (ERROR); 671 } else { 672 save_bufp->flags &= ~BUF_PIN; 673 return (SUCCESS); 674 } 675 case HASH_GET: 676 case HASH_DELETE: 677 default: 678 save_bufp->flags &= ~BUF_PIN; 679 return (ABNORMAL); 680 } 681 682 found: 683 switch (action) { 684 case HASH_PUTNEW: 685 save_bufp->flags &= ~BUF_PIN; 686 return (ABNORMAL); 687 case HASH_GET: 688 bp = (u_short *)rbufp->page; 689 if (bp[ndx + 1] < REAL_KEY) { 690 if (__big_return(hashp, rbufp, ndx, val, 0)) 691 return (ERROR); 692 } else { 693 val->data = (u_char *)rbufp->page + (int)bp[ndx + 1]; 694 val->size = bp[ndx] - bp[ndx + 1]; 695 } 696 break; 697 case HASH_PUT: 698 if ((__delpair(hashp, rbufp, ndx)) || 699 (__addel(hashp, rbufp, key, val))) { 700 save_bufp->flags &= ~BUF_PIN; 701 return (ERROR); 702 } 703 break; 704 case HASH_DELETE: 705 if (__delpair(hashp, rbufp, ndx)) 706 return (ERROR); 707 break; 708 default: 709 abort(); 710 } 711 save_bufp->flags &= ~BUF_PIN; 712 return (SUCCESS); 713 } 714 715 static int 716 hash_seq(dbp, key, data, flag) 717 const DB *dbp; 718 DBT *key, *data; 719 u_int flag; 720 { 721 register u_int bucket; 722 register BUFHEAD *bufp; 723 HTAB *hashp; 724 u_short *bp, ndx; 725 726 hashp = (HTAB *)dbp->internal; 727 if (flag && flag != R_FIRST && flag != R_NEXT) { 728 hashp->errno = errno = EINVAL; 729 return (ERROR); 730 } 731 #ifdef HASH_STATISTICS 732 hash_accesses++; 733 #endif 734 if ((hashp->cbucket < 0) || (flag == R_FIRST)) { 735 hashp->cbucket = 0; 736 hashp->cndx = 1; 737 hashp->cpage = NULL; 738 } 739 740 for (bp = NULL; !bp || !bp[0]; ) { 741 if (!(bufp = hashp->cpage)) { 742 for (bucket = hashp->cbucket; 743 bucket <= hashp->MAX_BUCKET; 744 bucket++, hashp->cndx = 1) { 745 bufp = __get_buf(hashp, bucket, NULL, 0); 746 if (!bufp) 747 return (ERROR); 748 hashp->cpage = bufp; 749 bp = (u_short *)bufp->page; 750 if (bp[0]) 751 break; 752 } 753 hashp->cbucket = bucket; 754 if (hashp->cbucket > hashp->MAX_BUCKET) { 755 hashp->cbucket = -1; 756 return (ABNORMAL); 757 } 758 } else 759 bp = (u_short *)hashp->cpage->page; 760 761 #ifdef DEBUG 762 assert(bp); 763 assert(bufp); 764 #endif 765 while (bp[hashp->cndx + 1] == OVFLPAGE) { 766 bufp = hashp->cpage = 767 __get_buf(hashp, bp[hashp->cndx], bufp, 0); 768 if (!bufp) 769 return (ERROR); 770 bp = (u_short *)(bufp->page); 771 hashp->cndx = 1; 772 } 773 if (!bp[0]) { 774 hashp->cpage = NULL; 775 ++hashp->cbucket; 776 } 777 } 778 ndx = hashp->cndx; 779 if (bp[ndx + 1] < REAL_KEY) { 780 if (__big_keydata(hashp, bufp, key, data, 1)) 781 return (ERROR); 782 } else { 783 key->data = (u_char *)hashp->cpage->page + bp[ndx]; 784 key->size = (ndx > 1 ? bp[ndx - 1] : hashp->BSIZE) - bp[ndx]; 785 data->data = (u_char *)hashp->cpage->page + bp[ndx + 1]; 786 data->size = bp[ndx] - bp[ndx + 1]; 787 ndx += 2; 788 if (ndx > bp[0]) { 789 hashp->cpage = NULL; 790 hashp->cbucket++; 791 hashp->cndx = 1; 792 } else 793 hashp->cndx = ndx; 794 } 795 return (SUCCESS); 796 } 797 798 /********************************* UTILITIES ************************/ 799 800 /* 801 * Returns: 802 * 0 ==> OK 803 * -1 ==> Error 804 */ 805 extern int 806 __expand_table(hashp) 807 HTAB *hashp; 808 { 809 u_int old_bucket, new_bucket; 810 int dirsize, new_segnum, spare_ndx; 811 812 #ifdef HASH_STATISTICS 813 hash_expansions++; 814 #endif 815 new_bucket = ++hashp->MAX_BUCKET; 816 old_bucket = (hashp->MAX_BUCKET & hashp->LOW_MASK); 817 818 new_segnum = new_bucket >> hashp->SSHIFT; 819 820 /* Check if we need a new segment */ 821 if (new_segnum >= hashp->nsegs) { 822 /* Check if we need to expand directory */ 823 if (new_segnum >= hashp->DSIZE) { 824 /* Reallocate directory */ 825 dirsize = hashp->DSIZE * sizeof(SEGMENT *); 826 if (!hash_realloc(&hashp->dir, dirsize, dirsize << 1)) 827 return (-1); 828 hashp->DSIZE = dirsize << 1; 829 } 830 if (!(hashp->dir[new_segnum] = 831 calloc(hashp->SGSIZE, sizeof(SEGMENT)))) 832 return (-1); 833 hashp->exsegs++; 834 hashp->nsegs++; 835 } 836 /* 837 * If the split point is increasing (MAX_BUCKET's log base 2 838 * * increases), we need to copy the current contents of the spare 839 * split bucket to the next bucket. 840 */ 841 spare_ndx = __log2(hashp->MAX_BUCKET + 1); 842 if (spare_ndx > hashp->OVFL_POINT) { 843 hashp->SPARES[spare_ndx] = hashp->SPARES[hashp->OVFL_POINT]; 844 hashp->OVFL_POINT = spare_ndx; 845 } 846 847 if (new_bucket > hashp->HIGH_MASK) { 848 /* Starting a new doubling */ 849 hashp->LOW_MASK = hashp->HIGH_MASK; 850 hashp->HIGH_MASK = new_bucket | hashp->LOW_MASK; 851 } 852 /* Relocate records to the new bucket */ 853 return (__split_page(hashp, old_bucket, new_bucket)); 854 } 855 856 /* 857 * If realloc guarantees that the pointer is not destroyed if the realloc 858 * fails, then this routine can go away. 859 */ 860 static void * 861 hash_realloc(p_ptr, oldsize, newsize) 862 SEGMENT **p_ptr; 863 int oldsize, newsize; 864 { 865 register void *p; 866 867 if (p = malloc(newsize)) { 868 memmove(p, *p_ptr, oldsize); 869 memset(p + oldsize, 0, newsize - oldsize); 870 free(*p_ptr); 871 *p_ptr = p; 872 } 873 return (p); 874 } 875 876 extern u_int 877 __call_hash(hashp, k, len) 878 HTAB *hashp; 879 char *k; 880 int len; 881 { 882 int n, bucket; 883 884 n = hashp->hash(k, len); 885 bucket = n & hashp->HIGH_MASK; 886 if (bucket > hashp->MAX_BUCKET) 887 bucket = bucket & hashp->LOW_MASK; 888 return (bucket); 889 } 890 891 /* 892 * Allocate segment table. On error, destroy the table and set errno. 893 * 894 * Returns 0 on success 895 */ 896 static int 897 alloc_segs(hashp, nsegs) 898 HTAB *hashp; 899 int nsegs; 900 { 901 register int i; 902 register SEGMENT store; 903 904 int save_errno; 905 906 if (!(hashp->dir = calloc(hashp->DSIZE, sizeof(SEGMENT *)))) { 907 save_errno = errno; 908 (void)hdestroy(hashp); 909 errno = save_errno; 910 return (-1); 911 } 912 /* Allocate segments */ 913 store = calloc(nsegs << hashp->SSHIFT, sizeof(SEGMENT)); 914 if (!store) { 915 save_errno = errno; 916 (void)hdestroy(hashp); 917 errno = save_errno; 918 return (-1); 919 } 920 for (i = 0; i < nsegs; i++, hashp->nsegs++) 921 hashp->dir[i] = &store[i << hashp->SSHIFT]; 922 return (0); 923 } 924 925 #if BYTE_ORDER == LITTLE_ENDIAN 926 /* 927 * Hashp->hdr needs to be byteswapped. 928 */ 929 static void 930 swap_header_copy(srcp, destp) 931 HASHHDR *srcp, *destp; 932 { 933 int i; 934 935 BLSWAP_COPY(srcp->magic, destp->magic); 936 BLSWAP_COPY(srcp->version, destp->version); 937 BLSWAP_COPY(srcp->lorder, destp->lorder); 938 BLSWAP_COPY(srcp->bsize, destp->bsize); 939 BLSWAP_COPY(srcp->bshift, destp->bshift); 940 BLSWAP_COPY(srcp->dsize, destp->dsize); 941 BLSWAP_COPY(srcp->ssize, destp->ssize); 942 BLSWAP_COPY(srcp->sshift, destp->sshift); 943 BLSWAP_COPY(srcp->ovfl_point, destp->ovfl_point); 944 BLSWAP_COPY(srcp->last_freed, destp->last_freed); 945 BLSWAP_COPY(srcp->max_bucket, destp->max_bucket); 946 BLSWAP_COPY(srcp->high_mask, destp->high_mask); 947 BLSWAP_COPY(srcp->low_mask, destp->low_mask); 948 BLSWAP_COPY(srcp->ffactor, destp->ffactor); 949 BLSWAP_COPY(srcp->nkeys, destp->nkeys); 950 BLSWAP_COPY(srcp->hdrpages, destp->hdrpages); 951 BLSWAP_COPY(srcp->h_charkey, destp->h_charkey); 952 for (i = 0; i < NCACHED; i++) { 953 BLSWAP_COPY(srcp->spares[i], destp->spares[i]); 954 BSSWAP_COPY(srcp->bitmaps[i], destp->bitmaps[i]); 955 } 956 } 957 958 static void 959 swap_header(hashp) 960 HTAB *hashp; 961 { 962 HASHHDR *hdrp; 963 int i; 964 965 hdrp = &hashp->hdr; 966 967 BLSWAP(hdrp->magic); 968 BLSWAP(hdrp->version); 969 BLSWAP(hdrp->lorder); 970 BLSWAP(hdrp->bsize); 971 BLSWAP(hdrp->bshift); 972 BLSWAP(hdrp->dsize); 973 BLSWAP(hdrp->ssize); 974 BLSWAP(hdrp->sshift); 975 BLSWAP(hdrp->ovfl_point); 976 BLSWAP(hdrp->last_freed); 977 BLSWAP(hdrp->max_bucket); 978 BLSWAP(hdrp->high_mask); 979 BLSWAP(hdrp->low_mask); 980 BLSWAP(hdrp->ffactor); 981 BLSWAP(hdrp->nkeys); 982 BLSWAP(hdrp->hdrpages); 983 BLSWAP(hdrp->h_charkey); 984 for (i = 0; i < NCACHED; i++) { 985 BLSWAP(hdrp->spares[i]); 986 BSSWAP(hdrp->bitmaps[i]); 987 } 988 } 989 #endif 990
Indexes created Wed Oct 29 01:09:52 GMT 2025