1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Margo Seltzer. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)hash_page.c 5.25 (Berkeley) 02/16/93"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 /* 16 * PACKAGE: hashing 17 * 18 * DESCRIPTION: 19 * Page manipulation for hashing package. 20 * 21 * ROUTINES: 22 * 23 * External 24 * __get_page 25 * __add_ovflpage 26 * Internal 27 * overflow_page 28 * open_temp 29 */ 30 31 #include <sys/types.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <signal.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <unistd.h> 40 #ifdef DEBUG 41 #include <assert.h> 42 #endif 43 44 #include <db.h> 45 #include "hash.h" 46 #include "page.h" 47 #include "extern.h" 48 49 static u_long *fetch_bitmap __P((HTAB *, int)); 50 static u_long first_free __P((u_long)); 51 static int open_temp __P((HTAB *)); 52 static u_short overflow_page __P((HTAB *)); 53 static void putpair __P((char *, const DBT *, const DBT *)); 54 static void squeeze_key __P((u_short *, const DBT *, const DBT *)); 55 static int ugly_split 56 __P((HTAB *, u_int, BUFHEAD *, BUFHEAD *, int, int)); 57 58 #define PAGE_INIT(P) { \ 59 ((u_short *)(P))[0] = 0; \ 60 ((u_short *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_short); \ 61 ((u_short *)(P))[2] = hashp->BSIZE; \ 62 } 63 64 /* 65 * This is called AFTER we have verified that there is room on the page for 66 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 67 * stuff on. 68 */ 69 static void 70 putpair(p, key, val) 71 char *p; 72 const DBT *key, *val; 73 { 74 register u_short *bp, n, off; 75 76 bp = (u_short *)p; 77 78 /* Enter the key first. */ 79 n = bp[0]; 80 81 off = OFFSET(bp) - key->size; 82 memmove(p + off, key->data, key->size); 83 bp[++n] = off; 84 85 /* Now the data. */ 86 off -= val->size; 87 memmove(p + off, val->data, val->size); 88 bp[++n] = off; 89 90 /* Adjust page info. */ 91 bp[0] = n; 92 bp[n + 1] = off - ((n + 3) * sizeof(u_short)); 93 bp[n + 2] = off; 94 } 95 96 /* 97 * Returns: 98 * 0 OK 99 * -1 error 100 */ 101 extern int 102 __delpair(hashp, bufp, ndx) 103 HTAB *hashp; 104 BUFHEAD *bufp; 105 register int ndx; 106 { 107 register u_short *bp, newoff; 108 register int n; 109 u_short pairlen; 110 111 bp = (u_short *)bufp->page; 112 n = bp[0]; 113 114 if (bp[ndx + 1] < REAL_KEY) 115 return (__big_delete(hashp, bufp)); 116 if (ndx != 1) 117 newoff = bp[ndx - 1]; 118 else 119 newoff = hashp->BSIZE; 120 pairlen = newoff - bp[ndx + 1]; 121 122 if (ndx != (n - 1)) { 123 /* Hard Case -- need to shuffle keys */ 124 register int i; 125 register char *src = bufp->page + (int)OFFSET(bp); 126 register char *dst = src + (int)pairlen; 127 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 128 129 /* Now adjust the pointers */ 130 for (i = ndx + 2; i <= n; i += 2) { 131 if (bp[i + 1] == OVFLPAGE) { 132 bp[i - 2] = bp[i]; 133 bp[i - 1] = bp[i + 1]; 134 } else { 135 bp[i - 2] = bp[i] + pairlen; 136 bp[i - 1] = bp[i + 1] + pairlen; 137 } 138 } 139 } 140 /* Finally adjust the page data */ 141 bp[n] = OFFSET(bp) + pairlen; 142 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_short); 143 bp[0] = n - 2; 144 hashp->NKEYS--; 145 146 bufp->flags |= BUF_MOD; 147 return (0); 148 } 149 /* 150 * Returns: 151 * 0 ==> OK 152 * -1 ==> Error 153 */ 154 extern int 155 __split_page(hashp, obucket, nbucket) 156 HTAB *hashp; 157 u_int obucket, nbucket; 158 { 159 register BUFHEAD *new_bufp, *old_bufp; 160 register u_short *ino; 161 register char *np; 162 DBT key, val; 163 int n, ndx, retval; 164 u_short copyto, diff, off, moved; 165 char *op; 166 167 copyto = (u_short)hashp->BSIZE; 168 off = (u_short)hashp->BSIZE; 169 old_bufp = __get_buf(hashp, obucket, NULL, 0); 170 if (old_bufp == NULL) 171 return (-1); 172 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 173 if (new_bufp == NULL) 174 return (-1); 175 176 old_bufp->flags |= (BUF_MOD | BUF_PIN); 177 new_bufp->flags |= (BUF_MOD | BUF_PIN); 178 179 ino = (u_short *)(op = old_bufp->page); 180 np = new_bufp->page; 181 182 moved = 0; 183 184 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 185 if (ino[n + 1] < REAL_KEY) { 186 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 187 (int)copyto, (int)moved); 188 old_bufp->flags &= ~BUF_PIN; 189 new_bufp->flags &= ~BUF_PIN; 190 return (retval); 191 192 } 193 key.data = (u_char *)op + ino[n]; 194 key.size = off - ino[n]; 195 196 if (__call_hash(hashp, key.data, key.size) == obucket) { 197 /* Don't switch page */ 198 diff = copyto - off; 199 if (diff) { 200 copyto = ino[n + 1] + diff; 201 memmove(op + copyto, op + ino[n + 1], 202 off - ino[n + 1]); 203 ino[ndx] = copyto + ino[n] - ino[n + 1]; 204 ino[ndx + 1] = copyto; 205 } else 206 copyto = ino[n + 1]; 207 ndx += 2; 208 } else { 209 /* Switch page */ 210 val.data = (u_char *)op + ino[n + 1]; 211 val.size = ino[n] - ino[n + 1]; 212 putpair(np, &key, &val); 213 moved += 2; 214 } 215 216 off = ino[n + 1]; 217 } 218 219 /* Now clean up the page */ 220 ino[0] -= moved; 221 FREESPACE(ino) = copyto - sizeof(u_short) * (ino[0] + 3); 222 OFFSET(ino) = copyto; 223 224 #ifdef DEBUG3 225 (void)fprintf(stderr, "split %d/%d\n", 226 ((u_short *)np)[0] / 2, 227 ((u_short *)op)[0] / 2); 228 #endif 229 /* unpin both pages */ 230 old_bufp->flags &= ~BUF_PIN; 231 new_bufp->flags &= ~BUF_PIN; 232 return (0); 233 } 234 235 /* 236 * Called when we encounter an overflow or big key/data page during split 237 * handling. This is special cased since we have to begin checking whether 238 * the key/data pairs fit on their respective pages and because we may need 239 * overflow pages for both the old and new pages. 240 * 241 * The first page might be a page with regular key/data pairs in which case 242 * we have a regular overflow condition and just need to go on to the next 243 * page or it might be a big key/data pair in which case we need to fix the 244 * big key/data pair. 245 * 246 * Returns: 247 * 0 ==> success 248 * -1 ==> failure 249 */ 250 static int 251 ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved) 252 HTAB *hashp; 253 u_int obucket; /* Same as __split_page. */ 254 BUFHEAD *old_bufp, *new_bufp; 255 int copyto; /* First byte on page which contains key/data values. */ 256 int moved; /* Number of pairs moved to new page. */ 257 { 258 register BUFHEAD *bufp; /* Buffer header for ino */ 259 register u_short *ino; /* Page keys come off of */ 260 register u_short *np; /* New page */ 261 register u_short *op; /* Page keys go on to if they aren't moving */ 262 263 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 264 DBT key, val; 265 SPLIT_RETURN ret; 266 u_short n, off, ov_addr, scopyto; 267 char *cino; /* Character value of ino */ 268 269 bufp = old_bufp; 270 ino = (u_short *)old_bufp->page; 271 np = (u_short *)new_bufp->page; 272 op = (u_short *)old_bufp->page; 273 last_bfp = NULL; 274 scopyto = (u_short)copyto; /* ANSI */ 275 276 n = ino[0] - 1; 277 while (n < ino[0]) { 278 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 279 /* 280 * Ov_addr gets set before reaching this point; there's 281 * always an overflow page before a big key/data page. 282 */ 283 if (__big_split(hashp, old_bufp, 284 new_bufp, bufp, ov_addr, obucket, &ret)) 285 return (-1); 286 old_bufp = ret.oldp; 287 if (!old_bufp) 288 return (-1); 289 op = (u_short *)old_bufp->page; 290 new_bufp = ret.newp; 291 if (!new_bufp) 292 return (-1); 293 np = (u_short *)new_bufp->page; 294 bufp = ret.nextp; 295 if (!bufp) 296 return (0); 297 cino = (char *)bufp->page; 298 ino = (u_short *)cino; 299 last_bfp = ret.nextp; 300 } else if (ino[n + 1] == OVFLPAGE) { 301 ov_addr = ino[n]; 302 /* 303 * Fix up the old page -- the extra 2 are the fields 304 * which contained the overflow information. 305 */ 306 ino[0] -= (moved + 2); 307 FREESPACE(ino) = 308 scopyto - sizeof(u_short) * (ino[0] + 3); 309 OFFSET(ino) = scopyto; 310 311 bufp = __get_buf(hashp, ov_addr, bufp, 0); 312 if (!bufp) 313 return (-1); 314 315 ino = (u_short *)bufp->page; 316 n = 1; 317 scopyto = hashp->BSIZE; 318 moved = 0; 319 320 if (last_bfp) 321 __free_ovflpage(hashp, last_bfp); 322 last_bfp = bufp; 323 } 324 /* Move regular sized pairs of there are any */ 325 off = hashp->BSIZE; 326 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 327 cino = (char *)ino; 328 key.data = (u_char *)cino + ino[n]; 329 key.size = off - ino[n]; 330 val.data = (u_char *)cino + ino[n + 1]; 331 val.size = ino[n] - ino[n + 1]; 332 off = ino[n + 1]; 333 334 if (__call_hash(hashp, key.data, key.size) == obucket) { 335 /* Keep on old page */ 336 if (PAIRFITS(op, (&key), (&val))) 337 putpair((char *)op, &key, &val); 338 else { 339 old_bufp = 340 __add_ovflpage(hashp, old_bufp); 341 if (!old_bufp) 342 return (-1); 343 op = (u_short *)old_bufp->page; 344 putpair((char *)op, &key, &val); 345 } 346 old_bufp->flags |= BUF_MOD; 347 } else { 348 /* Move to new page */ 349 if (PAIRFITS(np, (&key), (&val))) 350 putpair((char *)np, &key, &val); 351 else { 352 new_bufp = 353 __add_ovflpage(hashp, new_bufp); 354 if (!new_bufp) 355 return (-1); 356 np = (u_short *)new_bufp->page; 357 putpair((char *)np, &key, &val); 358 } 359 new_bufp->flags |= BUF_MOD; 360 } 361 } 362 } 363 if (last_bfp) 364 __free_ovflpage(hashp, last_bfp); 365 return (0); 366 } 367 368 /* 369 * Add the given pair to the page 370 * 371 * Returns: 372 * 0 ==> OK 373 * 1 ==> failure 374 */ 375 extern int 376 __addel(hashp, bufp, key, val) 377 HTAB *hashp; 378 BUFHEAD *bufp; 379 const DBT *key, *val; 380 { 381 register u_short *bp, *sop; 382 int do_expand; 383 384 bp = (u_short *)bufp->page; 385 do_expand = 0; 386 while (bp[0] && (bp[bp[0]] < REAL_KEY)) 387 /* Exception case */ 388 if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 389 /* This is a big-keydata pair */ 390 bufp = __add_ovflpage(hashp, bufp); 391 if (!bufp) 392 return (-1); 393 bp = (u_short *)bufp->page; 394 } else 395 /* Try to squeeze key on this page */ 396 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 397 squeeze_key(bp, key, val); 398 return (0); 399 } else { 400 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 401 if (!bufp) 402 return (-1); 403 bp = (u_short *)bufp->page; 404 } 405 406 if (PAIRFITS(bp, key, val)) 407 putpair(bufp->page, key, val); 408 else { 409 do_expand = 1; 410 bufp = __add_ovflpage(hashp, bufp); 411 if (!bufp) 412 return (-1); 413 sop = (u_short *)bufp->page; 414 415 if (PAIRFITS(sop, key, val)) 416 putpair((char *)sop, key, val); 417 else 418 if (__big_insert(hashp, bufp, key, val)) 419 return (-1); 420 } 421 bufp->flags |= BUF_MOD; 422 /* 423 * If the average number of keys per bucket exceeds the fill factor, 424 * expand the table. 425 */ 426 hashp->NKEYS++; 427 if (do_expand || 428 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 429 return (__expand_table(hashp)); 430 return (0); 431 } 432 433 /* 434 * 435 * Returns: 436 * pointer on success 437 * NULL on error 438 */ 439 extern BUFHEAD * 440 __add_ovflpage(hashp, bufp) 441 HTAB *hashp; 442 BUFHEAD *bufp; 443 { 444 register u_short *sp; 445 u_short ndx, ovfl_num; 446 #ifdef DEBUG1 447 int tmp1, tmp2; 448 #endif 449 sp = (u_short *)bufp->page; 450 bufp->flags |= BUF_MOD; 451 ovfl_num = overflow_page(hashp); 452 #ifdef DEBUG1 453 tmp1 = bufp->addr; 454 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 455 #endif 456 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 457 return (NULL); 458 bufp->ovfl->flags |= BUF_MOD; 459 #ifdef DEBUG1 460 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 461 tmp1, tmp2, bufp->ovfl->addr); 462 #endif 463 ndx = sp[0]; 464 /* 465 * Since a pair is allocated on a page only if there's room to add 466 * an overflow page, we know that the OVFL information will fit on 467 * the page. 468 */ 469 sp[ndx + 4] = OFFSET(sp); 470 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 471 sp[ndx + 1] = ovfl_num; 472 sp[ndx + 2] = OVFLPAGE; 473 sp[0] = ndx + 2; 474 #ifdef HASH_STATISTICS 475 hash_overflows++; 476 #endif 477 return (bufp->ovfl); 478 } 479 480 /* 481 * Returns: 482 * 0 indicates SUCCESS 483 * -1 indicates FAILURE 484 */ 485 extern int 486 __get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) 487 HTAB *hashp; 488 char *p; 489 u_int bucket; 490 int is_bucket, is_disk, is_bitmap; 491 { 492 register int fd, page, size; 493 int rsize; 494 u_short *bp; 495 496 fd = hashp->fp; 497 size = hashp->BSIZE; 498 499 if ((fd == -1) || !is_disk) { 500 PAGE_INIT(p); 501 return (0); 502 } 503 if (is_bucket) 504 page = BUCKET_TO_PAGE(bucket); 505 else 506 page = OADDR_TO_PAGE(bucket); 507 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 508 ((rsize = read(fd, p, size)) == -1)) 509 return (-1); 510 bp = (u_short *)p; 511 if (!rsize) 512 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 513 else 514 if (rsize != size) { 515 errno = EFTYPE; 516 return (-1); 517 } 518 if (!is_bitmap && !bp[0]) { 519 PAGE_INIT(p); 520 } else 521 if (hashp->LORDER != BYTE_ORDER) { 522 register int i, max; 523 524 if (is_bitmap) { 525 max = hashp->BSIZE >> 2; /* divide by 4 */ 526 for (i = 0; i < max; i++) 527 BLSWAP(((long *)p)[i]); 528 } else { 529 BSSWAP(bp[0]); 530 max = bp[0] + 2; 531 for (i = 1; i <= max; i++) 532 BSSWAP(bp[i]); 533 } 534 } 535 return (0); 536 } 537 538 /* 539 * Write page p to disk 540 * 541 * Returns: 542 * 0 ==> OK 543 * -1 ==>failure 544 */ 545 extern int 546 __put_page(hashp, p, bucket, is_bucket, is_bitmap) 547 HTAB *hashp; 548 char *p; 549 u_int bucket; 550 int is_bucket, is_bitmap; 551 { 552 register int fd, page, size; 553 int wsize; 554 555 size = hashp->BSIZE; 556 if ((hashp->fp == -1) && open_temp(hashp)) 557 return (-1); 558 fd = hashp->fp; 559 560 if (hashp->LORDER != BYTE_ORDER) { 561 register int i; 562 register int max; 563 564 if (is_bitmap) { 565 max = hashp->BSIZE >> 2; /* divide by 4 */ 566 for (i = 0; i < max; i++) 567 BLSWAP(((long *)p)[i]); 568 } else { 569 max = ((u_short *)p)[0] + 2; 570 for (i = 0; i <= max; i++) 571 BSSWAP(((u_short *)p)[i]); 572 } 573 } 574 if (is_bucket) 575 page = BUCKET_TO_PAGE(bucket); 576 else 577 page = OADDR_TO_PAGE(bucket); 578 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 579 ((wsize = write(fd, p, size)) == -1)) 580 /* Errno is set */ 581 return (-1); 582 if (wsize != size) { 583 errno = EFTYPE; 584 return (-1); 585 } 586 return (0); 587 } 588 589 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 590 /* 591 * Initialize a new bitmap page. Bitmap pages are left in memory 592 * once they are read in. 593 */ 594 extern int 595 __init_bitmap(hashp, pnum, nbits, ndx) 596 HTAB *hashp; 597 int pnum, nbits, ndx; 598 { 599 u_long *ip; 600 int clearbytes, clearints; 601 602 if (!(ip = malloc(hashp->BSIZE))) 603 return (1); 604 hashp->nmaps++; 605 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 606 clearbytes = clearints << INT_TO_BYTE; 607 (void)memset((char *)ip, 0, clearbytes); 608 (void)memset(((char *)ip) + clearbytes, 0xFF, 609 hashp->BSIZE - clearbytes); 610 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 611 SETBIT(ip, 0); 612 hashp->BITMAPS[ndx] = (u_short)pnum; 613 hashp->mapp[ndx] = ip; 614 return (0); 615 } 616 617 static u_long 618 first_free(map) 619 u_long map; 620 { 621 register u_long i, mask; 622 623 mask = 0x1; 624 for (i = 0; i < BITS_PER_MAP; i++) { 625 if (!(mask & map)) 626 return (i); 627 mask = mask << 1; 628 } 629 return (i); 630 } 631 632 static u_short 633 overflow_page(hashp) 634 HTAB *hashp; 635 { 636 register u_long *freep; 637 register int max_free, offset, splitnum; 638 u_short addr; 639 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 640 #ifdef DEBUG2 641 int tmp1, tmp2; 642 #endif 643 splitnum = hashp->OVFL_POINT; 644 max_free = hashp->SPARES[splitnum]; 645 646 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 647 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 648 649 /* Look through all the free maps to find the first free block */ 650 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 651 for ( i = first_page; i <= free_page; i++ ) { 652 if (!(freep = (u_long *)hashp->mapp[i]) && 653 !(freep = fetch_bitmap(hashp, i))) 654 return (NULL); 655 if (i == free_page) 656 in_use_bits = free_bit; 657 else 658 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 659 660 if (i == first_page) { 661 bit = hashp->LAST_FREED & 662 ((hashp->BSIZE << BYTE_SHIFT) - 1); 663 j = bit / BITS_PER_MAP; 664 bit = bit & ~(BITS_PER_MAP - 1); 665 } else { 666 bit = 0; 667 j = 0; 668 } 669 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 670 if (freep[j] != ALL_SET) 671 goto found; 672 } 673 674 /* No Free Page Found */ 675 hashp->LAST_FREED = hashp->SPARES[splitnum]; 676 hashp->SPARES[splitnum]++; 677 offset = hashp->SPARES[splitnum] - 678 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 679 680 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 681 if (offset > SPLITMASK) { 682 if (++splitnum >= NCACHED) { 683 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 684 return (NULL); 685 } 686 hashp->OVFL_POINT = splitnum; 687 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 688 hashp->SPARES[splitnum-1]--; 689 offset = 0; 690 } 691 692 /* Check if we need to allocate a new bitmap page */ 693 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 694 free_page++; 695 if (free_page >= NCACHED) { 696 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 697 return (NULL); 698 } 699 /* 700 * This is tricky. The 1 indicates that you want the new page 701 * allocated with 1 clear bit. Actually, you are going to 702 * allocate 2 pages from this map. The first is going to be 703 * the map page, the second is the overflow page we were 704 * looking for. The init_bitmap routine automatically, sets 705 * the first bit of itself to indicate that the bitmap itself 706 * is in use. We would explicitly set the second bit, but 707 * don't have to if we tell init_bitmap not to leave it clear 708 * in the first place. 709 */ 710 if (__init_bitmap(hashp, (int)OADDR_OF(splitnum, offset), 711 1, free_page)) 712 return (NULL); 713 hashp->SPARES[splitnum]++; 714 #ifdef DEBUG2 715 free_bit = 2; 716 #endif 717 offset++; 718 if (offset > SPLITMASK) { 719 if (++splitnum >= NCACHED) { 720 (void)write(STDERR_FILENO, OVMSG, 721 sizeof(OVMSG) - 1); 722 return (NULL); 723 } 724 hashp->OVFL_POINT = splitnum; 725 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 726 hashp->SPARES[splitnum-1]--; 727 offset = 0; 728 } 729 } else { 730 /* 731 * Free_bit addresses the last used bit. Bump it to address 732 * the first available bit. 733 */ 734 free_bit++; 735 SETBIT(freep, free_bit); 736 } 737 738 /* Calculate address of the new overflow page */ 739 addr = OADDR_OF(splitnum, offset); 740 #ifdef DEBUG2 741 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 742 addr, free_bit, free_page); 743 #endif 744 return (addr); 745 746 found: 747 bit = bit + first_free(freep[j]); 748 SETBIT(freep, bit); 749 #ifdef DEBUG2 750 tmp1 = bit; 751 tmp2 = i; 752 #endif 753 /* 754 * Bits are addressed starting with 0, but overflow pages are addressed 755 * beginning at 1. Bit is a bit addressnumber, so we need to increment 756 * it to convert it to a page number. 757 */ 758 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 759 if (bit >= hashp->LAST_FREED) 760 hashp->LAST_FREED = bit - 1; 761 762 /* Calculate the split number for this page */ 763 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 764 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 765 if (offset >= SPLITMASK) 766 return (NULL); /* Out of overflow pages */ 767 addr = OADDR_OF(i, offset); 768 #ifdef DEBUG2 769 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 770 addr, tmp1, tmp2); 771 #endif 772 773 /* Allocate and return the overflow page */ 774 return (addr); 775 } 776 777 /* 778 * Mark this overflow page as free. 779 */ 780 extern void 781 __free_ovflpage(hashp, obufp) 782 HTAB *hashp; 783 BUFHEAD *obufp; 784 { 785 register u_short addr; 786 u_long *freep; 787 int bit_address, free_page, free_bit; 788 u_short ndx; 789 790 addr = obufp->addr; 791 #ifdef DEBUG1 792 (void)fprintf(stderr, "Freeing %d\n", addr); 793 #endif 794 ndx = (((u_short)addr) >> SPLITSHIFT); 795 bit_address = 796 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 797 if (bit_address < hashp->LAST_FREED) 798 hashp->LAST_FREED = bit_address; 799 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 800 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 801 802 if (!(freep = hashp->mapp[free_page])) 803 freep = fetch_bitmap(hashp, free_page); 804 #ifdef DEBUG 805 /* 806 * This had better never happen. It means we tried to read a bitmap 807 * that has already had overflow pages allocated off it, and we 808 * failed to read it from the file. 809 */ 810 if (!freep) 811 assert(0); 812 #endif 813 CLRBIT(freep, free_bit); 814 #ifdef DEBUG2 815 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 816 obufp->addr, free_bit, free_page); 817 #endif 818 __reclaim_buf(hashp, obufp); 819 } 820 821 /* 822 * Returns: 823 * 0 success 824 * -1 failure 825 */ 826 static int 827 open_temp(hashp) 828 HTAB *hashp; 829 { 830 sigset_t set, oset; 831 static char namestr[] = "_hashXXXXXX"; 832 833 /* Block signals; make sure file goes away at process exit. */ 834 (void)sigfillset(&set); 835 (void)sigprocmask(SIG_BLOCK, &set, &oset); 836 if ((hashp->fp = mkstemp(namestr)) != -1) { 837 (void)unlink(namestr); 838 (void)fcntl(hashp->fp, F_SETFD, 1); 839 } 840 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 841 return (hashp->fp != -1 ? 0 : -1); 842 } 843 844 /* 845 * We have to know that the key will fit, but the last entry on the page is 846 * an overflow pair, so we need to shift things. 847 */ 848 static void 849 squeeze_key(sp, key, val) 850 u_short *sp; 851 const DBT *key, *val; 852 { 853 register char *p; 854 u_short free_space, n, off, pageno; 855 856 p = (char *)sp; 857 n = sp[0]; 858 free_space = FREESPACE(sp); 859 off = OFFSET(sp); 860 861 pageno = sp[n - 1]; 862 off -= key->size; 863 sp[n - 1] = off; 864 memmove(p + off, key->data, key->size); 865 off -= val->size; 866 sp[n] = off; 867 memmove(p + off, val->data, val->size); 868 sp[0] = n + 2; 869 sp[n + 1] = pageno; 870 sp[n + 2] = OVFLPAGE; 871 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 872 OFFSET(sp) = off; 873 } 874 875 static u_long * 876 fetch_bitmap(hashp, ndx) 877 HTAB *hashp; 878 int ndx; 879 { 880 if (ndx >= hashp->nmaps || 881 !(hashp->mapp[ndx] = malloc(hashp->BSIZE)) || 882 __get_page(hashp, (char *)hashp->mapp[ndx], 883 hashp->BITMAPS[ndx], 0, 1, 1)) 884 return (NULL); 885 return (hashp->mapp[ndx]); 886 } 887 888 #ifdef DEBUG4 889 int 890 print_chain(addr) 891 int addr; 892 { 893 BUFHEAD *bufp; 894 short *bp, oaddr; 895 896 (void)fprintf(stderr, "%d ", addr); 897 bufp = __get_buf(hashp, addr, NULL, 0); 898 bp = (short *)bufp->page; 899 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 900 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 901 oaddr = bp[bp[0] - 1]; 902 (void)fprintf(stderr, "%d ", (int)oaddr); 903 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 904 bp = (short *)bufp->page; 905 } 906 (void)fprintf(stderr, "\n"); 907 } 908 #endif 909