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 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)hash_page.c 8.4 (Berkeley) 02/21/94"; 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 if (__big_split(hashp, old_bufp, 280 new_bufp, bufp, bufp->addr, obucket, &ret)) 281 return (-1); 282 old_bufp = ret.oldp; 283 if (!old_bufp) 284 return (-1); 285 op = (u_short *)old_bufp->page; 286 new_bufp = ret.newp; 287 if (!new_bufp) 288 return (-1); 289 np = (u_short *)new_bufp->page; 290 bufp = ret.nextp; 291 if (!bufp) 292 return (0); 293 cino = (char *)bufp->page; 294 ino = (u_short *)cino; 295 last_bfp = ret.nextp; 296 } else if (ino[n + 1] == OVFLPAGE) { 297 ov_addr = ino[n]; 298 /* 299 * Fix up the old page -- the extra 2 are the fields 300 * which contained the overflow information. 301 */ 302 ino[0] -= (moved + 2); 303 FREESPACE(ino) = 304 scopyto - sizeof(u_short) * (ino[0] + 3); 305 OFFSET(ino) = scopyto; 306 307 bufp = __get_buf(hashp, ov_addr, bufp, 0); 308 if (!bufp) 309 return (-1); 310 311 ino = (u_short *)bufp->page; 312 n = 1; 313 scopyto = hashp->BSIZE; 314 moved = 0; 315 316 if (last_bfp) 317 __free_ovflpage(hashp, last_bfp); 318 last_bfp = bufp; 319 } 320 /* Move regular sized pairs of there are any */ 321 off = hashp->BSIZE; 322 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 323 cino = (char *)ino; 324 key.data = (u_char *)cino + ino[n]; 325 key.size = off - ino[n]; 326 val.data = (u_char *)cino + ino[n + 1]; 327 val.size = ino[n] - ino[n + 1]; 328 off = ino[n + 1]; 329 330 if (__call_hash(hashp, key.data, key.size) == obucket) { 331 /* Keep on old page */ 332 if (PAIRFITS(op, (&key), (&val))) 333 putpair((char *)op, &key, &val); 334 else { 335 old_bufp = 336 __add_ovflpage(hashp, old_bufp); 337 if (!old_bufp) 338 return (-1); 339 op = (u_short *)old_bufp->page; 340 putpair((char *)op, &key, &val); 341 } 342 old_bufp->flags |= BUF_MOD; 343 } else { 344 /* Move to new page */ 345 if (PAIRFITS(np, (&key), (&val))) 346 putpair((char *)np, &key, &val); 347 else { 348 new_bufp = 349 __add_ovflpage(hashp, new_bufp); 350 if (!new_bufp) 351 return (-1); 352 np = (u_short *)new_bufp->page; 353 putpair((char *)np, &key, &val); 354 } 355 new_bufp->flags |= BUF_MOD; 356 } 357 } 358 } 359 if (last_bfp) 360 __free_ovflpage(hashp, last_bfp); 361 return (0); 362 } 363 364 /* 365 * Add the given pair to the page 366 * 367 * Returns: 368 * 0 ==> OK 369 * 1 ==> failure 370 */ 371 extern int 372 __addel(hashp, bufp, key, val) 373 HTAB *hashp; 374 BUFHEAD *bufp; 375 const DBT *key, *val; 376 { 377 register u_short *bp, *sop; 378 int do_expand; 379 380 bp = (u_short *)bufp->page; 381 do_expand = 0; 382 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 383 /* Exception case */ 384 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 385 /* This is the last page of a big key/data pair 386 and we need to add another page */ 387 break; 388 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 389 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 390 if (!bufp) 391 return (-1); 392 bp = (u_short *)bufp->page; 393 } else 394 /* Try to squeeze key on this page */ 395 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 396 squeeze_key(bp, key, val); 397 return (0); 398 } else { 399 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 400 if (!bufp) 401 return (-1); 402 bp = (u_short *)bufp->page; 403 } 404 405 if (PAIRFITS(bp, key, val)) 406 putpair(bufp->page, key, val); 407 else { 408 do_expand = 1; 409 bufp = __add_ovflpage(hashp, bufp); 410 if (!bufp) 411 return (-1); 412 sop = (u_short *)bufp->page; 413 414 if (PAIRFITS(sop, key, val)) 415 putpair((char *)sop, key, val); 416 else 417 if (__big_insert(hashp, bufp, key, val)) 418 return (-1); 419 } 420 bufp->flags |= BUF_MOD; 421 /* 422 * If the average number of keys per bucket exceeds the fill factor, 423 * expand the table. 424 */ 425 hashp->NKEYS++; 426 if (do_expand || 427 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 428 return (__expand_table(hashp)); 429 return (0); 430 } 431 432 /* 433 * 434 * Returns: 435 * pointer on success 436 * NULL on error 437 */ 438 extern BUFHEAD * 439 __add_ovflpage(hashp, bufp) 440 HTAB *hashp; 441 BUFHEAD *bufp; 442 { 443 register u_short *sp; 444 u_short ndx, ovfl_num; 445 #ifdef DEBUG1 446 int tmp1, tmp2; 447 #endif 448 sp = (u_short *)bufp->page; 449 450 /* Check if we are dynamically determining the fill factor */ 451 if (hashp->FFACTOR == DEF_FFACTOR) { 452 hashp->FFACTOR = sp[0] >> 1; 453 if (hashp->FFACTOR < MIN_FFACTOR) 454 hashp->FFACTOR = MIN_FFACTOR; 455 } 456 bufp->flags |= BUF_MOD; 457 ovfl_num = overflow_page(hashp); 458 #ifdef DEBUG1 459 tmp1 = bufp->addr; 460 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 461 #endif 462 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 463 return (NULL); 464 bufp->ovfl->flags |= BUF_MOD; 465 #ifdef DEBUG1 466 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 467 tmp1, tmp2, bufp->ovfl->addr); 468 #endif 469 ndx = sp[0]; 470 /* 471 * Since a pair is allocated on a page only if there's room to add 472 * an overflow page, we know that the OVFL information will fit on 473 * the page. 474 */ 475 sp[ndx + 4] = OFFSET(sp); 476 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 477 sp[ndx + 1] = ovfl_num; 478 sp[ndx + 2] = OVFLPAGE; 479 sp[0] = ndx + 2; 480 #ifdef HASH_STATISTICS 481 hash_overflows++; 482 #endif 483 return (bufp->ovfl); 484 } 485 486 /* 487 * Returns: 488 * 0 indicates SUCCESS 489 * -1 indicates FAILURE 490 */ 491 extern int 492 __get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) 493 HTAB *hashp; 494 char *p; 495 u_int bucket; 496 int is_bucket, is_disk, is_bitmap; 497 { 498 register int fd, page, size; 499 int rsize; 500 u_short *bp; 501 502 fd = hashp->fp; 503 size = hashp->BSIZE; 504 505 if ((fd == -1) || !is_disk) { 506 PAGE_INIT(p); 507 return (0); 508 } 509 if (is_bucket) 510 page = BUCKET_TO_PAGE(bucket); 511 else 512 page = OADDR_TO_PAGE(bucket); 513 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 514 ((rsize = read(fd, p, size)) == -1)) 515 return (-1); 516 bp = (u_short *)p; 517 if (!rsize) 518 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 519 else 520 if (rsize != size) { 521 errno = EFTYPE; 522 return (-1); 523 } 524 if (!is_bitmap && !bp[0]) { 525 PAGE_INIT(p); 526 } else 527 if (hashp->LORDER != BYTE_ORDER) { 528 register int i, max; 529 530 if (is_bitmap) { 531 max = hashp->BSIZE >> 2; /* divide by 4 */ 532 for (i = 0; i < max; i++) 533 M_32_SWAP(((long *)p)[i]); 534 } else { 535 M_16_SWAP(bp[0]); 536 max = bp[0] + 2; 537 for (i = 1; i <= max; i++) 538 M_16_SWAP(bp[i]); 539 } 540 } 541 return (0); 542 } 543 544 /* 545 * Write page p to disk 546 * 547 * Returns: 548 * 0 ==> OK 549 * -1 ==>failure 550 */ 551 extern int 552 __put_page(hashp, p, bucket, is_bucket, is_bitmap) 553 HTAB *hashp; 554 char *p; 555 u_int bucket; 556 int is_bucket, is_bitmap; 557 { 558 register int fd, page, size; 559 int wsize; 560 561 size = hashp->BSIZE; 562 if ((hashp->fp == -1) && open_temp(hashp)) 563 return (-1); 564 fd = hashp->fp; 565 566 if (hashp->LORDER != BYTE_ORDER) { 567 register int i; 568 register int max; 569 570 if (is_bitmap) { 571 max = hashp->BSIZE >> 2; /* divide by 4 */ 572 for (i = 0; i < max; i++) 573 M_32_SWAP(((long *)p)[i]); 574 } else { 575 max = ((u_short *)p)[0] + 2; 576 for (i = 0; i <= max; i++) 577 M_16_SWAP(((u_short *)p)[i]); 578 } 579 } 580 if (is_bucket) 581 page = BUCKET_TO_PAGE(bucket); 582 else 583 page = OADDR_TO_PAGE(bucket); 584 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 585 ((wsize = write(fd, p, size)) == -1)) 586 /* Errno is set */ 587 return (-1); 588 if (wsize != size) { 589 errno = EFTYPE; 590 return (-1); 591 } 592 return (0); 593 } 594 595 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 596 /* 597 * Initialize a new bitmap page. Bitmap pages are left in memory 598 * once they are read in. 599 */ 600 extern int 601 __init_bitmap(hashp, pnum, nbits, ndx) 602 HTAB *hashp; 603 int pnum, nbits, ndx; 604 { 605 u_long *ip; 606 int clearbytes, clearints; 607 608 if ((ip = (u_long *)malloc(hashp->BSIZE)) == NULL) 609 return (1); 610 hashp->nmaps++; 611 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 612 clearbytes = clearints << INT_TO_BYTE; 613 (void)memset((char *)ip, 0, clearbytes); 614 (void)memset(((char *)ip) + clearbytes, 0xFF, 615 hashp->BSIZE - clearbytes); 616 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 617 SETBIT(ip, 0); 618 hashp->BITMAPS[ndx] = (u_short)pnum; 619 hashp->mapp[ndx] = ip; 620 return (0); 621 } 622 623 static u_long 624 first_free(map) 625 u_long map; 626 { 627 register u_long i, mask; 628 629 mask = 0x1; 630 for (i = 0; i < BITS_PER_MAP; i++) { 631 if (!(mask & map)) 632 return (i); 633 mask = mask << 1; 634 } 635 return (i); 636 } 637 638 static u_short 639 overflow_page(hashp) 640 HTAB *hashp; 641 { 642 register u_long *freep; 643 register int max_free, offset, splitnum; 644 u_short addr; 645 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 646 #ifdef DEBUG2 647 int tmp1, tmp2; 648 #endif 649 splitnum = hashp->OVFL_POINT; 650 max_free = hashp->SPARES[splitnum]; 651 652 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 653 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 654 655 /* Look through all the free maps to find the first free block */ 656 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 657 for ( i = first_page; i <= free_page; i++ ) { 658 if (!(freep = (u_long *)hashp->mapp[i]) && 659 !(freep = fetch_bitmap(hashp, i))) 660 return (NULL); 661 if (i == free_page) 662 in_use_bits = free_bit; 663 else 664 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 665 666 if (i == first_page) { 667 bit = hashp->LAST_FREED & 668 ((hashp->BSIZE << BYTE_SHIFT) - 1); 669 j = bit / BITS_PER_MAP; 670 bit = bit & ~(BITS_PER_MAP - 1); 671 } else { 672 bit = 0; 673 j = 0; 674 } 675 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 676 if (freep[j] != ALL_SET) 677 goto found; 678 } 679 680 /* No Free Page Found */ 681 hashp->LAST_FREED = hashp->SPARES[splitnum]; 682 hashp->SPARES[splitnum]++; 683 offset = hashp->SPARES[splitnum] - 684 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 685 686 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 687 if (offset > SPLITMASK) { 688 if (++splitnum >= NCACHED) { 689 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 690 return (NULL); 691 } 692 hashp->OVFL_POINT = splitnum; 693 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 694 hashp->SPARES[splitnum-1]--; 695 offset = 1; 696 } 697 698 /* Check if we need to allocate a new bitmap page */ 699 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 700 free_page++; 701 if (free_page >= NCACHED) { 702 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 703 return (NULL); 704 } 705 /* 706 * This is tricky. The 1 indicates that you want the new page 707 * allocated with 1 clear bit. Actually, you are going to 708 * allocate 2 pages from this map. The first is going to be 709 * the map page, the second is the overflow page we were 710 * looking for. The init_bitmap routine automatically, sets 711 * the first bit of itself to indicate that the bitmap itself 712 * is in use. We would explicitly set the second bit, but 713 * don't have to if we tell init_bitmap not to leave it clear 714 * in the first place. 715 */ 716 if (__init_bitmap(hashp, (int)OADDR_OF(splitnum, offset), 717 1, free_page)) 718 return (NULL); 719 hashp->SPARES[splitnum]++; 720 #ifdef DEBUG2 721 free_bit = 2; 722 #endif 723 offset++; 724 if (offset > SPLITMASK) { 725 if (++splitnum >= NCACHED) { 726 (void)write(STDERR_FILENO, OVMSG, 727 sizeof(OVMSG) - 1); 728 return (NULL); 729 } 730 hashp->OVFL_POINT = splitnum; 731 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 732 hashp->SPARES[splitnum-1]--; 733 offset = 0; 734 } 735 } else { 736 /* 737 * Free_bit addresses the last used bit. Bump it to address 738 * the first available bit. 739 */ 740 free_bit++; 741 SETBIT(freep, free_bit); 742 } 743 744 /* Calculate address of the new overflow page */ 745 addr = OADDR_OF(splitnum, offset); 746 #ifdef DEBUG2 747 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 748 addr, free_bit, free_page); 749 #endif 750 return (addr); 751 752 found: 753 bit = bit + first_free(freep[j]); 754 SETBIT(freep, bit); 755 #ifdef DEBUG2 756 tmp1 = bit; 757 tmp2 = i; 758 #endif 759 /* 760 * Bits are addressed starting with 0, but overflow pages are addressed 761 * beginning at 1. Bit is a bit addressnumber, so we need to increment 762 * it to convert it to a page number. 763 */ 764 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 765 if (bit >= hashp->LAST_FREED) 766 hashp->LAST_FREED = bit - 1; 767 768 /* Calculate the split number for this page */ 769 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 770 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 771 if (offset >= SPLITMASK) 772 return (NULL); /* Out of overflow pages */ 773 addr = OADDR_OF(i, offset); 774 #ifdef DEBUG2 775 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 776 addr, tmp1, tmp2); 777 #endif 778 779 /* Allocate and return the overflow page */ 780 return (addr); 781 } 782 783 /* 784 * Mark this overflow page as free. 785 */ 786 extern void 787 __free_ovflpage(hashp, obufp) 788 HTAB *hashp; 789 BUFHEAD *obufp; 790 { 791 register u_short addr; 792 u_long *freep; 793 int bit_address, free_page, free_bit; 794 u_short ndx; 795 796 addr = obufp->addr; 797 #ifdef DEBUG1 798 (void)fprintf(stderr, "Freeing %d\n", addr); 799 #endif 800 ndx = (((u_short)addr) >> SPLITSHIFT); 801 bit_address = 802 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 803 if (bit_address < hashp->LAST_FREED) 804 hashp->LAST_FREED = bit_address; 805 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 806 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 807 808 if (!(freep = hashp->mapp[free_page])) 809 freep = fetch_bitmap(hashp, free_page); 810 #ifdef DEBUG 811 /* 812 * This had better never happen. It means we tried to read a bitmap 813 * that has already had overflow pages allocated off it, and we 814 * failed to read it from the file. 815 */ 816 if (!freep) 817 assert(0); 818 #endif 819 CLRBIT(freep, free_bit); 820 #ifdef DEBUG2 821 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 822 obufp->addr, free_bit, free_page); 823 #endif 824 __reclaim_buf(hashp, obufp); 825 } 826 827 /* 828 * Returns: 829 * 0 success 830 * -1 failure 831 */ 832 static int 833 open_temp(hashp) 834 HTAB *hashp; 835 { 836 sigset_t set, oset; 837 static char namestr[] = "_hashXXXXXX"; 838 839 /* Block signals; make sure file goes away at process exit. */ 840 (void)sigfillset(&set); 841 (void)sigprocmask(SIG_BLOCK, &set, &oset); 842 if ((hashp->fp = mkstemp(namestr)) != -1) { 843 (void)unlink(namestr); 844 (void)fcntl(hashp->fp, F_SETFD, 1); 845 } 846 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 847 return (hashp->fp != -1 ? 0 : -1); 848 } 849 850 /* 851 * We have to know that the key will fit, but the last entry on the page is 852 * an overflow pair, so we need to shift things. 853 */ 854 static void 855 squeeze_key(sp, key, val) 856 u_short *sp; 857 const DBT *key, *val; 858 { 859 register char *p; 860 u_short free_space, n, off, pageno; 861 862 p = (char *)sp; 863 n = sp[0]; 864 free_space = FREESPACE(sp); 865 off = OFFSET(sp); 866 867 pageno = sp[n - 1]; 868 off -= key->size; 869 sp[n - 1] = off; 870 memmove(p + off, key->data, key->size); 871 off -= val->size; 872 sp[n] = off; 873 memmove(p + off, val->data, val->size); 874 sp[0] = n + 2; 875 sp[n + 1] = pageno; 876 sp[n + 2] = OVFLPAGE; 877 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 878 OFFSET(sp) = off; 879 } 880 881 static u_long * 882 fetch_bitmap(hashp, ndx) 883 HTAB *hashp; 884 int ndx; 885 { 886 if (ndx >= hashp->nmaps) 887 return (NULL); 888 if ((hashp->mapp[ndx] = (u_long *)malloc(hashp->BSIZE)) == NULL) 889 return (NULL); 890 if (__get_page(hashp, 891 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 892 free(hashp->mapp[ndx]); 893 return (NULL); 894 } 895 return (hashp->mapp[ndx]); 896 } 897 898 #ifdef DEBUG4 899 int 900 print_chain(addr) 901 int addr; 902 { 903 BUFHEAD *bufp; 904 short *bp, oaddr; 905 906 (void)fprintf(stderr, "%d ", addr); 907 bufp = __get_buf(hashp, addr, NULL, 0); 908 bp = (short *)bufp->page; 909 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 910 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 911 oaddr = bp[bp[0] - 1]; 912 (void)fprintf(stderr, "%d ", (int)oaddr); 913 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 914 bp = (short *)bufp->page; 915 } 916 (void)fprintf(stderr, "\n"); 917 } 918 #endif 919