hash_page.c revision 1.7
1 /* $NetBSD: hash_page.c,v 1.7 1995/02/27 13:22:34 cgd 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)hash_page.c 8.6 (Berkeley) 6/16/94"; 42 #else 43 static char rcsid[] = "$NetBSD: hash_page.c,v 1.7 1995/02/27 13:22:34 cgd Exp $"; 44 #endif 45 #endif /* LIBC_SCCS and not lint */ 46 47 /* 48 * PACKAGE: hashing 49 * 50 * DESCRIPTION: 51 * Page manipulation for hashing package. 52 * 53 * ROUTINES: 54 * 55 * External 56 * __get_page 57 * __add_ovflpage 58 * Internal 59 * overflow_page 60 * open_temp 61 */ 62 63 #include <sys/types.h> 64 65 #include <errno.h> 66 #include <fcntl.h> 67 #include <signal.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <string.h> 71 #include <unistd.h> 72 #ifdef DEBUG 73 #include <assert.h> 74 #endif 75 76 #include <db.h> 77 #include "hash.h" 78 #include "page.h" 79 #include "extern.h" 80 81 static u_int32_t *fetch_bitmap __P((HTAB *, int)); 82 static u_int32_t first_free __P((u_int32_t)); 83 static int open_temp __P((HTAB *)); 84 static u_int16_t overflow_page __P((HTAB *)); 85 static void putpair __P((char *, const DBT *, const DBT *)); 86 static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *)); 87 static int ugly_split 88 __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int)); 89 90 #define PAGE_INIT(P) { \ 91 ((u_int16_t *)(P))[0] = 0; \ 92 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \ 93 ((u_int16_t *)(P))[2] = hashp->BSIZE; \ 94 } 95 96 /* 97 * This is called AFTER we have verified that there is room on the page for 98 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 99 * stuff on. 100 */ 101 static void 102 putpair(p, key, val) 103 char *p; 104 const DBT *key, *val; 105 { 106 register u_int16_t *bp, n, off; 107 108 bp = (u_int16_t *)p; 109 110 /* Enter the key first. */ 111 n = bp[0]; 112 113 off = OFFSET(bp) - key->size; 114 memmove(p + off, key->data, key->size); 115 bp[++n] = off; 116 117 /* Now the data. */ 118 off -= val->size; 119 memmove(p + off, val->data, val->size); 120 bp[++n] = off; 121 122 /* Adjust page info. */ 123 bp[0] = n; 124 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t)); 125 bp[n + 2] = off; 126 } 127 128 /* 129 * Returns: 130 * 0 OK 131 * -1 error 132 */ 133 extern int 134 __delpair(hashp, bufp, ndx) 135 HTAB *hashp; 136 BUFHEAD *bufp; 137 register int ndx; 138 { 139 register u_int16_t *bp, newoff; 140 register int n; 141 u_int16_t pairlen; 142 143 bp = (u_int16_t *)bufp->page; 144 n = bp[0]; 145 146 if (bp[ndx + 1] < REAL_KEY) 147 return (__big_delete(hashp, bufp)); 148 if (ndx != 1) 149 newoff = bp[ndx - 1]; 150 else 151 newoff = hashp->BSIZE; 152 pairlen = newoff - bp[ndx + 1]; 153 154 if (ndx != (n - 1)) { 155 /* Hard Case -- need to shuffle keys */ 156 register int i; 157 register char *src = bufp->page + (int)OFFSET(bp); 158 register char *dst = src + (int)pairlen; 159 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 160 161 /* Now adjust the pointers */ 162 for (i = ndx + 2; i <= n; i += 2) { 163 if (bp[i + 1] == OVFLPAGE) { 164 bp[i - 2] = bp[i]; 165 bp[i - 1] = bp[i + 1]; 166 } else { 167 bp[i - 2] = bp[i] + pairlen; 168 bp[i - 1] = bp[i + 1] + pairlen; 169 } 170 } 171 } 172 /* Finally adjust the page data */ 173 bp[n] = OFFSET(bp) + pairlen; 174 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t); 175 bp[0] = n - 2; 176 hashp->NKEYS--; 177 178 bufp->flags |= BUF_MOD; 179 return (0); 180 } 181 /* 182 * Returns: 183 * 0 ==> OK 184 * -1 ==> Error 185 */ 186 extern int 187 __split_page(hashp, obucket, nbucket) 188 HTAB *hashp; 189 u_int32_t obucket, nbucket; 190 { 191 register BUFHEAD *new_bufp, *old_bufp; 192 register u_int16_t *ino; 193 register char *np; 194 DBT key, val; 195 int n, ndx, retval; 196 u_int16_t copyto, diff, off, moved; 197 char *op; 198 199 copyto = (u_int16_t)hashp->BSIZE; 200 off = (u_int16_t)hashp->BSIZE; 201 old_bufp = __get_buf(hashp, obucket, NULL, 0); 202 if (old_bufp == NULL) 203 return (-1); 204 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 205 if (new_bufp == NULL) 206 return (-1); 207 208 old_bufp->flags |= (BUF_MOD | BUF_PIN); 209 new_bufp->flags |= (BUF_MOD | BUF_PIN); 210 211 ino = (u_int16_t *)(op = old_bufp->page); 212 np = new_bufp->page; 213 214 moved = 0; 215 216 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 217 if (ino[n + 1] < REAL_KEY) { 218 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 219 (int)copyto, (int)moved); 220 old_bufp->flags &= ~BUF_PIN; 221 new_bufp->flags &= ~BUF_PIN; 222 return (retval); 223 224 } 225 key.data = (u_char *)op + ino[n]; 226 key.size = off - ino[n]; 227 228 if (__call_hash(hashp, key.data, key.size) == obucket) { 229 /* Don't switch page */ 230 diff = copyto - off; 231 if (diff) { 232 copyto = ino[n + 1] + diff; 233 memmove(op + copyto, op + ino[n + 1], 234 off - ino[n + 1]); 235 ino[ndx] = copyto + ino[n] - ino[n + 1]; 236 ino[ndx + 1] = copyto; 237 } else 238 copyto = ino[n + 1]; 239 ndx += 2; 240 } else { 241 /* Switch page */ 242 val.data = (u_char *)op + ino[n + 1]; 243 val.size = ino[n] - ino[n + 1]; 244 putpair(np, &key, &val); 245 moved += 2; 246 } 247 248 off = ino[n + 1]; 249 } 250 251 /* Now clean up the page */ 252 ino[0] -= moved; 253 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3); 254 OFFSET(ino) = copyto; 255 256 #ifdef DEBUG3 257 (void)fprintf(stderr, "split %d/%d\n", 258 ((u_int16_t *)np)[0] / 2, 259 ((u_int16_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 283 ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved) 284 HTAB *hashp; 285 u_int32_t obucket; /* Same as __split_page. */ 286 BUFHEAD *old_bufp, *new_bufp; 287 int copyto; /* First byte on page which contains key/data values. */ 288 int moved; /* Number of pairs moved to new page. */ 289 { 290 register BUFHEAD *bufp; /* Buffer header for ino */ 291 register u_int16_t *ino; /* Page keys come off of */ 292 register u_int16_t *np; /* New page */ 293 register u_int16_t *op; /* Page keys go on to if they aren't moving */ 294 295 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 296 DBT key, val; 297 SPLIT_RETURN ret; 298 u_int16_t n, off, ov_addr, scopyto; 299 char *cino; /* Character value of ino */ 300 301 bufp = old_bufp; 302 ino = (u_int16_t *)old_bufp->page; 303 np = (u_int16_t *)new_bufp->page; 304 op = (u_int16_t *)old_bufp->page; 305 last_bfp = NULL; 306 scopyto = (u_int16_t)copyto; /* ANSI */ 307 308 n = ino[0] - 1; 309 while (n < ino[0]) { 310 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 311 if (__big_split(hashp, old_bufp, 312 new_bufp, bufp, bufp->addr, obucket, &ret)) 313 return (-1); 314 old_bufp = ret.oldp; 315 if (!old_bufp) 316 return (-1); 317 op = (u_int16_t *)old_bufp->page; 318 new_bufp = ret.newp; 319 if (!new_bufp) 320 return (-1); 321 np = (u_int16_t *)new_bufp->page; 322 bufp = ret.nextp; 323 if (!bufp) 324 return (0); 325 cino = (char *)bufp->page; 326 ino = (u_int16_t *)cino; 327 last_bfp = ret.nextp; 328 } else if (ino[n + 1] == OVFLPAGE) { 329 ov_addr = ino[n]; 330 /* 331 * Fix up the old page -- the extra 2 are the fields 332 * which contained the overflow information. 333 */ 334 ino[0] -= (moved + 2); 335 FREESPACE(ino) = 336 scopyto - sizeof(u_int16_t) * (ino[0] + 3); 337 OFFSET(ino) = scopyto; 338 339 bufp = __get_buf(hashp, ov_addr, bufp, 0); 340 if (!bufp) 341 return (-1); 342 343 ino = (u_int16_t *)bufp->page; 344 n = 1; 345 scopyto = hashp->BSIZE; 346 moved = 0; 347 348 if (last_bfp) 349 __free_ovflpage(hashp, last_bfp); 350 last_bfp = bufp; 351 } 352 /* Move regular sized pairs of there are any */ 353 off = hashp->BSIZE; 354 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 355 cino = (char *)ino; 356 key.data = (u_char *)cino + ino[n]; 357 key.size = off - ino[n]; 358 val.data = (u_char *)cino + ino[n + 1]; 359 val.size = ino[n] - ino[n + 1]; 360 off = ino[n + 1]; 361 362 if (__call_hash(hashp, key.data, key.size) == obucket) { 363 /* Keep on old page */ 364 if (PAIRFITS(op, (&key), (&val))) 365 putpair((char *)op, &key, &val); 366 else { 367 old_bufp = 368 __add_ovflpage(hashp, old_bufp); 369 if (!old_bufp) 370 return (-1); 371 op = (u_int16_t *)old_bufp->page; 372 putpair((char *)op, &key, &val); 373 } 374 old_bufp->flags |= BUF_MOD; 375 } else { 376 /* Move to new page */ 377 if (PAIRFITS(np, (&key), (&val))) 378 putpair((char *)np, &key, &val); 379 else { 380 new_bufp = 381 __add_ovflpage(hashp, new_bufp); 382 if (!new_bufp) 383 return (-1); 384 np = (u_int16_t *)new_bufp->page; 385 putpair((char *)np, &key, &val); 386 } 387 new_bufp->flags |= BUF_MOD; 388 } 389 } 390 } 391 if (last_bfp) 392 __free_ovflpage(hashp, last_bfp); 393 return (0); 394 } 395 396 /* 397 * Add the given pair to the page 398 * 399 * Returns: 400 * 0 ==> OK 401 * 1 ==> failure 402 */ 403 extern int 404 __addel(hashp, bufp, key, val) 405 HTAB *hashp; 406 BUFHEAD *bufp; 407 const DBT *key, *val; 408 { 409 register u_int16_t *bp, *sop; 410 int do_expand; 411 412 bp = (u_int16_t *)bufp->page; 413 do_expand = 0; 414 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 415 /* Exception case */ 416 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 417 /* This is the last page of a big key/data pair 418 and we need to add another page */ 419 break; 420 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 421 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 422 if (!bufp) 423 return (-1); 424 bp = (u_int16_t *)bufp->page; 425 } else 426 /* Try to squeeze key on this page */ 427 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 428 squeeze_key(bp, key, val); 429 return (0); 430 } else { 431 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 432 if (!bufp) 433 return (-1); 434 bp = (u_int16_t *)bufp->page; 435 } 436 437 if (PAIRFITS(bp, key, val)) 438 putpair(bufp->page, key, val); 439 else { 440 do_expand = 1; 441 bufp = __add_ovflpage(hashp, bufp); 442 if (!bufp) 443 return (-1); 444 sop = (u_int16_t *)bufp->page; 445 446 if (PAIRFITS(sop, key, val)) 447 putpair((char *)sop, key, val); 448 else 449 if (__big_insert(hashp, bufp, key, val)) 450 return (-1); 451 } 452 bufp->flags |= BUF_MOD; 453 /* 454 * If the average number of keys per bucket exceeds the fill factor, 455 * expand the table. 456 */ 457 hashp->NKEYS++; 458 if (do_expand || 459 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 460 return (__expand_table(hashp)); 461 return (0); 462 } 463 464 /* 465 * 466 * Returns: 467 * pointer on success 468 * NULL on error 469 */ 470 extern BUFHEAD * 471 __add_ovflpage(hashp, bufp) 472 HTAB *hashp; 473 BUFHEAD *bufp; 474 { 475 register u_int16_t *sp; 476 u_int16_t ndx, ovfl_num; 477 #ifdef DEBUG1 478 int tmp1, tmp2; 479 #endif 480 sp = (u_int16_t *)bufp->page; 481 482 /* Check if we are dynamically determining the fill factor */ 483 if (hashp->FFACTOR == DEF_FFACTOR) { 484 hashp->FFACTOR = sp[0] >> 1; 485 if (hashp->FFACTOR < MIN_FFACTOR) 486 hashp->FFACTOR = MIN_FFACTOR; 487 } 488 bufp->flags |= BUF_MOD; 489 ovfl_num = overflow_page(hashp); 490 #ifdef DEBUG1 491 tmp1 = bufp->addr; 492 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 493 #endif 494 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 495 return (NULL); 496 bufp->ovfl->flags |= BUF_MOD; 497 #ifdef DEBUG1 498 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 499 tmp1, tmp2, bufp->ovfl->addr); 500 #endif 501 ndx = sp[0]; 502 /* 503 * Since a pair is allocated on a page only if there's room to add 504 * an overflow page, we know that the OVFL information will fit on 505 * the page. 506 */ 507 sp[ndx + 4] = OFFSET(sp); 508 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 509 sp[ndx + 1] = ovfl_num; 510 sp[ndx + 2] = OVFLPAGE; 511 sp[0] = ndx + 2; 512 #ifdef HASH_STATISTICS 513 hash_overflows++; 514 #endif 515 return (bufp->ovfl); 516 } 517 518 /* 519 * Returns: 520 * 0 indicates SUCCESS 521 * -1 indicates FAILURE 522 */ 523 extern int 524 __get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) 525 HTAB *hashp; 526 char *p; 527 u_int32_t bucket; 528 int is_bucket, is_disk, is_bitmap; 529 { 530 register int fd, page, size; 531 int rsize; 532 u_int16_t *bp; 533 534 fd = hashp->fp; 535 size = hashp->BSIZE; 536 537 if ((fd == -1) || !is_disk) { 538 PAGE_INIT(p); 539 return (0); 540 } 541 if (is_bucket) 542 page = BUCKET_TO_PAGE(bucket); 543 else 544 page = OADDR_TO_PAGE(bucket); 545 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 546 ((rsize = read(fd, p, size)) == -1)) 547 return (-1); 548 bp = (u_int16_t *)p; 549 if (!rsize) 550 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 551 else 552 if (rsize != size) { 553 errno = EFTYPE; 554 return (-1); 555 } 556 if (!is_bitmap && !bp[0]) { 557 PAGE_INIT(p); 558 } else 559 if (hashp->LORDER != BYTE_ORDER) { 560 register int i, max; 561 562 if (is_bitmap) { 563 max = hashp->BSIZE >> 2; /* divide by 4 */ 564 for (i = 0; i < max; i++) 565 M_32_SWAP(((int *)p)[i]); 566 } else { 567 M_16_SWAP(bp[0]); 568 max = bp[0] + 2; 569 for (i = 1; i <= max; i++) 570 M_16_SWAP(bp[i]); 571 } 572 } 573 return (0); 574 } 575 576 /* 577 * Write page p to disk 578 * 579 * Returns: 580 * 0 ==> OK 581 * -1 ==>failure 582 */ 583 extern int 584 __put_page(hashp, p, bucket, is_bucket, is_bitmap) 585 HTAB *hashp; 586 char *p; 587 u_int32_t bucket; 588 int is_bucket, is_bitmap; 589 { 590 register int fd, page, size; 591 int wsize; 592 593 size = hashp->BSIZE; 594 if ((hashp->fp == -1) && open_temp(hashp)) 595 return (-1); 596 fd = hashp->fp; 597 598 if (hashp->LORDER != BYTE_ORDER) { 599 register int i; 600 register int max; 601 602 if (is_bitmap) { 603 max = hashp->BSIZE >> 2; /* divide by 4 */ 604 for (i = 0; i < max; i++) 605 M_32_SWAP(((int *)p)[i]); 606 } else { 607 max = ((u_int16_t *)p)[0] + 2; 608 for (i = 0; i <= max; i++) 609 M_16_SWAP(((u_int16_t *)p)[i]); 610 } 611 } 612 if (is_bucket) 613 page = BUCKET_TO_PAGE(bucket); 614 else 615 page = OADDR_TO_PAGE(bucket); 616 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 617 ((wsize = write(fd, p, size)) == -1)) 618 /* Errno is set */ 619 return (-1); 620 if (wsize != size) { 621 errno = EFTYPE; 622 return (-1); 623 } 624 return (0); 625 } 626 627 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 628 /* 629 * Initialize a new bitmap page. Bitmap pages are left in memory 630 * once they are read in. 631 */ 632 extern int 633 __ibitmap(hashp, pnum, nbits, ndx) 634 HTAB *hashp; 635 int pnum, nbits, ndx; 636 { 637 u_int32_t *ip; 638 int clearbytes, clearints; 639 640 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 641 return (1); 642 hashp->nmaps++; 643 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 644 clearbytes = clearints << INT_TO_BYTE; 645 (void)memset((char *)ip, 0, clearbytes); 646 (void)memset(((char *)ip) + clearbytes, 0xFF, 647 hashp->BSIZE - clearbytes); 648 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 649 SETBIT(ip, 0); 650 hashp->BITMAPS[ndx] = (u_int16_t)pnum; 651 hashp->mapp[ndx] = ip; 652 return (0); 653 } 654 655 static u_int32_t 656 first_free(map) 657 u_int32_t map; 658 { 659 register u_int32_t i, mask; 660 661 mask = 0x1; 662 for (i = 0; i < BITS_PER_MAP; i++) { 663 if (!(mask & map)) 664 return (i); 665 mask = mask << 1; 666 } 667 return (i); 668 } 669 670 static u_int16_t 671 overflow_page(hashp) 672 HTAB *hashp; 673 { 674 register u_int32_t *freep; 675 register int max_free, offset, splitnum; 676 u_int16_t addr; 677 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 678 #ifdef DEBUG2 679 int tmp1, tmp2; 680 #endif 681 splitnum = hashp->OVFL_POINT; 682 max_free = hashp->SPARES[splitnum]; 683 684 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 685 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 686 687 /* Look through all the free maps to find the first free block */ 688 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 689 for ( i = first_page; i <= free_page; i++ ) { 690 if (!(freep = (u_int32_t *)hashp->mapp[i]) && 691 !(freep = fetch_bitmap(hashp, i))) 692 return (NULL); 693 if (i == free_page) 694 in_use_bits = free_bit; 695 else 696 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 697 698 if (i == first_page) { 699 bit = hashp->LAST_FREED & 700 ((hashp->BSIZE << BYTE_SHIFT) - 1); 701 j = bit / BITS_PER_MAP; 702 bit = bit & ~(BITS_PER_MAP - 1); 703 } else { 704 bit = 0; 705 j = 0; 706 } 707 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 708 if (freep[j] != ALL_SET) 709 goto found; 710 } 711 712 /* No Free Page Found */ 713 hashp->LAST_FREED = hashp->SPARES[splitnum]; 714 hashp->SPARES[splitnum]++; 715 offset = hashp->SPARES[splitnum] - 716 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 717 718 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 719 if (offset > SPLITMASK) { 720 if (++splitnum >= NCACHED) { 721 (void)write(STDERR_FILENO, OVMSG, 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 = 1; 728 } 729 730 /* Check if we need to allocate a new bitmap page */ 731 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 732 free_page++; 733 if (free_page >= NCACHED) { 734 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 735 return (NULL); 736 } 737 /* 738 * This is tricky. The 1 indicates that you want the new page 739 * allocated with 1 clear bit. Actually, you are going to 740 * allocate 2 pages from this map. The first is going to be 741 * the map page, the second is the overflow page we were 742 * looking for. The init_bitmap routine automatically, sets 743 * the first bit of itself to indicate that the bitmap itself 744 * is in use. We would explicitly set the second bit, but 745 * don't have to if we tell init_bitmap not to leave it clear 746 * in the first place. 747 */ 748 if (__ibitmap(hashp, (int)OADDR_OF(splitnum, offset), 749 1, free_page)) 750 return (NULL); 751 hashp->SPARES[splitnum]++; 752 #ifdef DEBUG2 753 free_bit = 2; 754 #endif 755 offset++; 756 if (offset > SPLITMASK) { 757 if (++splitnum >= NCACHED) { 758 (void)write(STDERR_FILENO, OVMSG, 759 sizeof(OVMSG) - 1); 760 return (NULL); 761 } 762 hashp->OVFL_POINT = splitnum; 763 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 764 hashp->SPARES[splitnum-1]--; 765 offset = 0; 766 } 767 } else { 768 /* 769 * Free_bit addresses the last used bit. Bump it to address 770 * the first available bit. 771 */ 772 free_bit++; 773 SETBIT(freep, free_bit); 774 } 775 776 /* Calculate address of the new overflow page */ 777 addr = OADDR_OF(splitnum, offset); 778 #ifdef DEBUG2 779 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 780 addr, free_bit, free_page); 781 #endif 782 return (addr); 783 784 found: 785 bit = bit + first_free(freep[j]); 786 SETBIT(freep, bit); 787 #ifdef DEBUG2 788 tmp1 = bit; 789 tmp2 = i; 790 #endif 791 /* 792 * Bits are addressed starting with 0, but overflow pages are addressed 793 * beginning at 1. Bit is a bit addressnumber, so we need to increment 794 * it to convert it to a page number. 795 */ 796 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 797 if (bit >= hashp->LAST_FREED) 798 hashp->LAST_FREED = bit - 1; 799 800 /* Calculate the split number for this page */ 801 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 802 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 803 if (offset >= SPLITMASK) 804 return (NULL); /* Out of overflow pages */ 805 addr = OADDR_OF(i, offset); 806 #ifdef DEBUG2 807 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 808 addr, tmp1, tmp2); 809 #endif 810 811 /* Allocate and return the overflow page */ 812 return (addr); 813 } 814 815 /* 816 * Mark this overflow page as free. 817 */ 818 extern void 819 __free_ovflpage(hashp, obufp) 820 HTAB *hashp; 821 BUFHEAD *obufp; 822 { 823 register u_int16_t addr; 824 u_int32_t *freep; 825 int bit_address, free_page, free_bit; 826 u_int16_t ndx; 827 828 addr = obufp->addr; 829 #ifdef DEBUG1 830 (void)fprintf(stderr, "Freeing %d\n", addr); 831 #endif 832 ndx = (((u_int16_t)addr) >> SPLITSHIFT); 833 bit_address = 834 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 835 if (bit_address < hashp->LAST_FREED) 836 hashp->LAST_FREED = bit_address; 837 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 838 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 839 840 if (!(freep = hashp->mapp[free_page])) 841 freep = fetch_bitmap(hashp, free_page); 842 #ifdef DEBUG 843 /* 844 * This had better never happen. It means we tried to read a bitmap 845 * that has already had overflow pages allocated off it, and we 846 * failed to read it from the file. 847 */ 848 if (!freep) 849 assert(0); 850 #endif 851 CLRBIT(freep, free_bit); 852 #ifdef DEBUG2 853 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 854 obufp->addr, free_bit, free_page); 855 #endif 856 __reclaim_buf(hashp, obufp); 857 } 858 859 /* 860 * Returns: 861 * 0 success 862 * -1 failure 863 */ 864 static int 865 open_temp(hashp) 866 HTAB *hashp; 867 { 868 sigset_t set, oset; 869 static char namestr[] = "_hashXXXXXX"; 870 871 /* Block signals; make sure file goes away at process exit. */ 872 (void)sigfillset(&set); 873 (void)sigprocmask(SIG_BLOCK, &set, &oset); 874 if ((hashp->fp = mkstemp(namestr)) != -1) { 875 (void)unlink(namestr); 876 (void)fcntl(hashp->fp, F_SETFD, 1); 877 } 878 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 879 return (hashp->fp != -1 ? 0 : -1); 880 } 881 882 /* 883 * We have to know that the key will fit, but the last entry on the page is 884 * an overflow pair, so we need to shift things. 885 */ 886 static void 887 squeeze_key(sp, key, val) 888 u_int16_t *sp; 889 const DBT *key, *val; 890 { 891 register char *p; 892 u_int16_t free_space, n, off, pageno; 893 894 p = (char *)sp; 895 n = sp[0]; 896 free_space = FREESPACE(sp); 897 off = OFFSET(sp); 898 899 pageno = sp[n - 1]; 900 off -= key->size; 901 sp[n - 1] = off; 902 memmove(p + off, key->data, key->size); 903 off -= val->size; 904 sp[n] = off; 905 memmove(p + off, val->data, val->size); 906 sp[0] = n + 2; 907 sp[n + 1] = pageno; 908 sp[n + 2] = OVFLPAGE; 909 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 910 OFFSET(sp) = off; 911 } 912 913 static u_int32_t * 914 fetch_bitmap(hashp, ndx) 915 HTAB *hashp; 916 int ndx; 917 { 918 if (ndx >= hashp->nmaps) 919 return (NULL); 920 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 921 return (NULL); 922 if (__get_page(hashp, 923 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 924 free(hashp->mapp[ndx]); 925 return (NULL); 926 } 927 return (hashp->mapp[ndx]); 928 } 929 930 #ifdef DEBUG4 931 int 932 print_chain(addr) 933 int addr; 934 { 935 BUFHEAD *bufp; 936 short *bp, oaddr; 937 938 (void)fprintf(stderr, "%d ", addr); 939 bufp = __get_buf(hashp, addr, NULL, 0); 940 bp = (short *)bufp->page; 941 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 942 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 943 oaddr = bp[bp[0] - 1]; 944 (void)fprintf(stderr, "%d ", (int)oaddr); 945 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 946 bp = (short *)bufp->page; 947 } 948 (void)fprintf(stderr, "\n"); 949 } 950 #endif 951
Indexes created Tue Sep 23 22:09:46 GMT 2025