hash_page.c revision 1.12
1 /* $NetBSD: hash_page.c,v 1.12 1998/10/14 12:06:49 kleink 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 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94"; 43 #else 44 __RCSID("$NetBSD: hash_page.c,v 1.12 1998/10/14 12:06:49 kleink Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 /* 49 * PACKAGE: hashing 50 * 51 * DESCRIPTION: 52 * Page manipulation for hashing package. 53 * 54 * ROUTINES: 55 * 56 * External 57 * __get_page 58 * __add_ovflpage 59 * Internal 60 * overflow_page 61 * open_temp 62 */ 63 64 #include "namespace.h" 65 66 #include <sys/types.h> 67 68 #include <errno.h> 69 #include <fcntl.h> 70 #include <signal.h> 71 #include <stdio.h> 72 #include <stdlib.h> 73 #include <string.h> 74 #include <unistd.h> 75 #ifdef DEBUG 76 #include <assert.h> 77 #endif 78 79 #include <db.h> 80 #include "hash.h" 81 #include "page.h" 82 #include "extern.h" 83 84 static u_int32_t *fetch_bitmap __P((HTAB *, int)); 85 static u_int32_t first_free __P((u_int32_t)); 86 static int open_temp __P((HTAB *)); 87 static u_int16_t overflow_page __P((HTAB *)); 88 static void putpair __P((char *, const DBT *, const DBT *)); 89 static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *)); 90 static int ugly_split 91 __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int)); 92 93 #define PAGE_INIT(P) { \ 94 ((u_int16_t *)(P))[0] = 0; \ 95 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \ 96 ((u_int16_t *)(P))[2] = hashp->BSIZE; \ 97 } 98 99 /* 100 * This is called AFTER we have verified that there is room on the page for 101 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 102 * stuff on. 103 */ 104 static void 105 putpair(p, key, val) 106 char *p; 107 const DBT *key, *val; 108 { 109 register u_int16_t *bp, n, off; 110 111 bp = (u_int16_t *)p; 112 113 /* Enter the key first. */ 114 n = bp[0]; 115 116 off = OFFSET(bp) - key->size; 117 memmove(p + off, key->data, key->size); 118 bp[++n] = off; 119 120 /* Now the data. */ 121 off -= val->size; 122 memmove(p + off, val->data, val->size); 123 bp[++n] = off; 124 125 /* Adjust page info. */ 126 bp[0] = n; 127 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t)); 128 bp[n + 2] = off; 129 } 130 131 /* 132 * Returns: 133 * 0 OK 134 * -1 error 135 */ 136 extern int 137 __delpair(hashp, bufp, ndx) 138 HTAB *hashp; 139 BUFHEAD *bufp; 140 register int ndx; 141 { 142 register u_int16_t *bp, newoff; 143 register int n; 144 u_int16_t pairlen; 145 146 bp = (u_int16_t *)bufp->page; 147 n = bp[0]; 148 149 if (bp[ndx + 1] < REAL_KEY) 150 return (__big_delete(hashp, bufp)); 151 if (ndx != 1) 152 newoff = bp[ndx - 1]; 153 else 154 newoff = hashp->BSIZE; 155 pairlen = newoff - bp[ndx + 1]; 156 157 if (ndx != (n - 1)) { 158 /* Hard Case -- need to shuffle keys */ 159 register int i; 160 register char *src = bufp->page + (int)OFFSET(bp); 161 register char *dst = src + (int)pairlen; 162 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 163 164 /* Now adjust the pointers */ 165 for (i = ndx + 2; i <= n; i += 2) { 166 if (bp[i + 1] == OVFLPAGE) { 167 bp[i - 2] = bp[i]; 168 bp[i - 1] = bp[i + 1]; 169 } else { 170 bp[i - 2] = bp[i] + pairlen; 171 bp[i - 1] = bp[i + 1] + pairlen; 172 } 173 } 174 } 175 /* Finally adjust the page data */ 176 bp[n] = OFFSET(bp) + pairlen; 177 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t); 178 bp[0] = n - 2; 179 hashp->NKEYS--; 180 181 bufp->flags |= BUF_MOD; 182 return (0); 183 } 184 /* 185 * Returns: 186 * 0 ==> OK 187 * -1 ==> Error 188 */ 189 extern int 190 __split_page(hashp, obucket, nbucket) 191 HTAB *hashp; 192 u_int32_t obucket, nbucket; 193 { 194 register BUFHEAD *new_bufp, *old_bufp; 195 register u_int16_t *ino; 196 register char *np; 197 DBT key, val; 198 int n, ndx, retval; 199 u_int16_t copyto, diff, off, moved; 200 char *op; 201 202 copyto = (u_int16_t)hashp->BSIZE; 203 off = (u_int16_t)hashp->BSIZE; 204 old_bufp = __get_buf(hashp, obucket, NULL, 0); 205 if (old_bufp == NULL) 206 return (-1); 207 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 208 if (new_bufp == NULL) 209 return (-1); 210 211 old_bufp->flags |= (BUF_MOD | BUF_PIN); 212 new_bufp->flags |= (BUF_MOD | BUF_PIN); 213 214 ino = (u_int16_t *)(op = old_bufp->page); 215 np = new_bufp->page; 216 217 moved = 0; 218 219 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 220 if (ino[n + 1] < REAL_KEY) { 221 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 222 (int)copyto, (int)moved); 223 old_bufp->flags &= ~BUF_PIN; 224 new_bufp->flags &= ~BUF_PIN; 225 return (retval); 226 227 } 228 key.data = (u_char *)op + ino[n]; 229 key.size = off - ino[n]; 230 231 if (__call_hash(hashp, key.data, key.size) == obucket) { 232 /* Don't switch page */ 233 diff = copyto - off; 234 if (diff) { 235 copyto = ino[n + 1] + diff; 236 memmove(op + copyto, op + ino[n + 1], 237 off - ino[n + 1]); 238 ino[ndx] = copyto + ino[n] - ino[n + 1]; 239 ino[ndx + 1] = copyto; 240 } else 241 copyto = ino[n + 1]; 242 ndx += 2; 243 } else { 244 /* Switch page */ 245 val.data = (u_char *)op + ino[n + 1]; 246 val.size = ino[n] - ino[n + 1]; 247 putpair(np, &key, &val); 248 moved += 2; 249 } 250 251 off = ino[n + 1]; 252 } 253 254 /* Now clean up the page */ 255 ino[0] -= moved; 256 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3); 257 OFFSET(ino) = copyto; 258 259 #ifdef DEBUG3 260 (void)fprintf(stderr, "split %d/%d\n", 261 ((u_int16_t *)np)[0] / 2, 262 ((u_int16_t *)op)[0] / 2); 263 #endif 264 /* unpin both pages */ 265 old_bufp->flags &= ~BUF_PIN; 266 new_bufp->flags &= ~BUF_PIN; 267 return (0); 268 } 269 270 /* 271 * Called when we encounter an overflow or big key/data page during split 272 * handling. This is special cased since we have to begin checking whether 273 * the key/data pairs fit on their respective pages and because we may need 274 * overflow pages for both the old and new pages. 275 * 276 * The first page might be a page with regular key/data pairs in which case 277 * we have a regular overflow condition and just need to go on to the next 278 * page or it might be a big key/data pair in which case we need to fix the 279 * big key/data pair. 280 * 281 * Returns: 282 * 0 ==> success 283 * -1 ==> failure 284 */ 285 static int 286 ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved) 287 HTAB *hashp; 288 u_int32_t obucket; /* Same as __split_page. */ 289 BUFHEAD *old_bufp, *new_bufp; 290 int copyto; /* First byte on page which contains key/data values. */ 291 int moved; /* Number of pairs moved to new page. */ 292 { 293 register BUFHEAD *bufp; /* Buffer header for ino */ 294 register u_int16_t *ino; /* Page keys come off of */ 295 register u_int16_t *np; /* New page */ 296 register u_int16_t *op; /* Page keys go on to if they aren't moving */ 297 298 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 299 DBT key, val; 300 SPLIT_RETURN ret; 301 u_int16_t n, off, ov_addr, scopyto; 302 char *cino; /* Character value of ino */ 303 304 bufp = old_bufp; 305 ino = (u_int16_t *)old_bufp->page; 306 np = (u_int16_t *)new_bufp->page; 307 op = (u_int16_t *)old_bufp->page; 308 last_bfp = NULL; 309 scopyto = (u_int16_t)copyto; /* ANSI */ 310 311 n = ino[0] - 1; 312 while (n < ino[0]) { 313 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 314 if (__big_split(hashp, old_bufp, 315 new_bufp, bufp, bufp->addr, obucket, &ret)) 316 return (-1); 317 old_bufp = ret.oldp; 318 if (!old_bufp) 319 return (-1); 320 op = (u_int16_t *)old_bufp->page; 321 new_bufp = ret.newp; 322 if (!new_bufp) 323 return (-1); 324 np = (u_int16_t *)new_bufp->page; 325 bufp = ret.nextp; 326 if (!bufp) 327 return (0); 328 cino = (char *)bufp->page; 329 ino = (u_int16_t *)cino; 330 last_bfp = ret.nextp; 331 } else if (ino[n + 1] == OVFLPAGE) { 332 ov_addr = ino[n]; 333 /* 334 * Fix up the old page -- the extra 2 are the fields 335 * which contained the overflow information. 336 */ 337 ino[0] -= (moved + 2); 338 FREESPACE(ino) = 339 scopyto - sizeof(u_int16_t) * (ino[0] + 3); 340 OFFSET(ino) = scopyto; 341 342 bufp = __get_buf(hashp, ov_addr, bufp, 0); 343 if (!bufp) 344 return (-1); 345 346 ino = (u_int16_t *)bufp->page; 347 n = 1; 348 scopyto = hashp->BSIZE; 349 moved = 0; 350 351 if (last_bfp) 352 __free_ovflpage(hashp, last_bfp); 353 last_bfp = bufp; 354 } 355 /* Move regular sized pairs of there are any */ 356 off = hashp->BSIZE; 357 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 358 cino = (char *)ino; 359 key.data = (u_char *)cino + ino[n]; 360 key.size = off - ino[n]; 361 val.data = (u_char *)cino + ino[n + 1]; 362 val.size = ino[n] - ino[n + 1]; 363 off = ino[n + 1]; 364 365 if (__call_hash(hashp, key.data, key.size) == obucket) { 366 /* Keep on old page */ 367 if (PAIRFITS(op, (&key), (&val))) 368 putpair((char *)op, &key, &val); 369 else { 370 old_bufp = 371 __add_ovflpage(hashp, old_bufp); 372 if (!old_bufp) 373 return (-1); 374 op = (u_int16_t *)old_bufp->page; 375 putpair((char *)op, &key, &val); 376 } 377 old_bufp->flags |= BUF_MOD; 378 } else { 379 /* Move to new page */ 380 if (PAIRFITS(np, (&key), (&val))) 381 putpair((char *)np, &key, &val); 382 else { 383 new_bufp = 384 __add_ovflpage(hashp, new_bufp); 385 if (!new_bufp) 386 return (-1); 387 np = (u_int16_t *)new_bufp->page; 388 putpair((char *)np, &key, &val); 389 } 390 new_bufp->flags |= BUF_MOD; 391 } 392 } 393 } 394 if (last_bfp) 395 __free_ovflpage(hashp, last_bfp); 396 return (0); 397 } 398 399 /* 400 * Add the given pair to the page 401 * 402 * Returns: 403 * 0 ==> OK 404 * 1 ==> failure 405 */ 406 extern int 407 __addel(hashp, bufp, key, val) 408 HTAB *hashp; 409 BUFHEAD *bufp; 410 const DBT *key, *val; 411 { 412 register u_int16_t *bp, *sop; 413 int do_expand; 414 415 bp = (u_int16_t *)bufp->page; 416 do_expand = 0; 417 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 418 /* Exception case */ 419 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 420 /* This is the last page of a big key/data pair 421 and we need to add another page */ 422 break; 423 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 424 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 425 if (!bufp) 426 return (-1); 427 bp = (u_int16_t *)bufp->page; 428 } else 429 /* Try to squeeze key on this page */ 430 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 431 squeeze_key(bp, key, val); 432 return (0); 433 } else { 434 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 435 if (!bufp) 436 return (-1); 437 bp = (u_int16_t *)bufp->page; 438 } 439 440 if (PAIRFITS(bp, key, val)) 441 putpair(bufp->page, key, val); 442 else { 443 do_expand = 1; 444 bufp = __add_ovflpage(hashp, bufp); 445 if (!bufp) 446 return (-1); 447 sop = (u_int16_t *)bufp->page; 448 449 if (PAIRFITS(sop, key, val)) 450 putpair((char *)sop, key, val); 451 else 452 if (__big_insert(hashp, bufp, key, val)) 453 return (-1); 454 } 455 bufp->flags |= BUF_MOD; 456 /* 457 * If the average number of keys per bucket exceeds the fill factor, 458 * expand the table. 459 */ 460 hashp->NKEYS++; 461 if (do_expand || 462 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 463 return (__expand_table(hashp)); 464 return (0); 465 } 466 467 /* 468 * 469 * Returns: 470 * pointer on success 471 * NULL on error 472 */ 473 extern BUFHEAD * 474 __add_ovflpage(hashp, bufp) 475 HTAB *hashp; 476 BUFHEAD *bufp; 477 { 478 register u_int16_t *sp; 479 u_int16_t ndx, ovfl_num; 480 #ifdef DEBUG1 481 int tmp1, tmp2; 482 #endif 483 sp = (u_int16_t *)bufp->page; 484 485 /* Check if we are dynamically determining the fill factor */ 486 if (hashp->FFACTOR == DEF_FFACTOR) { 487 hashp->FFACTOR = sp[0] >> 1; 488 if (hashp->FFACTOR < MIN_FFACTOR) 489 hashp->FFACTOR = MIN_FFACTOR; 490 } 491 bufp->flags |= BUF_MOD; 492 ovfl_num = overflow_page(hashp); 493 #ifdef DEBUG1 494 tmp1 = bufp->addr; 495 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 496 #endif 497 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 498 return (NULL); 499 bufp->ovfl->flags |= BUF_MOD; 500 #ifdef DEBUG1 501 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 502 tmp1, tmp2, bufp->ovfl->addr); 503 #endif 504 ndx = sp[0]; 505 /* 506 * Since a pair is allocated on a page only if there's room to add 507 * an overflow page, we know that the OVFL information will fit on 508 * the page. 509 */ 510 sp[ndx + 4] = OFFSET(sp); 511 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 512 sp[ndx + 1] = ovfl_num; 513 sp[ndx + 2] = OVFLPAGE; 514 sp[0] = ndx + 2; 515 #ifdef HASH_STATISTICS 516 hash_overflows++; 517 #endif 518 return (bufp->ovfl); 519 } 520 521 /* 522 * Returns: 523 * 0 indicates SUCCESS 524 * -1 indicates FAILURE 525 */ 526 extern int 527 __get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) 528 HTAB *hashp; 529 char *p; 530 u_int32_t bucket; 531 int is_bucket, is_disk, is_bitmap; 532 { 533 register int fd, page, size; 534 int rsize; 535 u_int16_t *bp; 536 537 fd = hashp->fp; 538 size = hashp->BSIZE; 539 540 if ((fd == -1) || !is_disk) { 541 PAGE_INIT(p); 542 return (0); 543 } 544 if (is_bucket) 545 page = BUCKET_TO_PAGE(bucket); 546 else 547 page = OADDR_TO_PAGE(bucket); 548 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 549 return (-1); 550 bp = (u_int16_t *)p; 551 if (!rsize) 552 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 553 else 554 if (rsize != size) { 555 errno = EFTYPE; 556 return (-1); 557 } 558 if (!is_bitmap && !bp[0]) { 559 PAGE_INIT(p); 560 } else 561 if (hashp->LORDER != BYTE_ORDER) { 562 register int i, max; 563 564 if (is_bitmap) { 565 max = hashp->BSIZE >> 2; /* divide by 4 */ 566 for (i = 0; i < max; i++) 567 M_32_SWAP(((int *)p)[i]); 568 } else { 569 M_16_SWAP(bp[0]); 570 max = bp[0] + 2; 571 for (i = 1; i <= max; i++) 572 M_16_SWAP(bp[i]); 573 } 574 } 575 return (0); 576 } 577 578 /* 579 * Write page p to disk 580 * 581 * Returns: 582 * 0 ==> OK 583 * -1 ==>failure 584 */ 585 extern int 586 __put_page(hashp, p, bucket, is_bucket, is_bitmap) 587 HTAB *hashp; 588 char *p; 589 u_int32_t bucket; 590 int is_bucket, is_bitmap; 591 { 592 register int fd, page, size; 593 int wsize; 594 595 size = hashp->BSIZE; 596 if ((hashp->fp == -1) && open_temp(hashp)) 597 return (-1); 598 fd = hashp->fp; 599 600 if (hashp->LORDER != BYTE_ORDER) { 601 register int i; 602 register int max; 603 604 if (is_bitmap) { 605 max = hashp->BSIZE >> 2; /* divide by 4 */ 606 for (i = 0; i < max; i++) 607 M_32_SWAP(((int *)p)[i]); 608 } else { 609 max = ((u_int16_t *)p)[0] + 2; 610 for (i = 0; i <= max; i++) 611 M_16_SWAP(((u_int16_t *)p)[i]); 612 } 613 } 614 if (is_bucket) 615 page = BUCKET_TO_PAGE(bucket); 616 else 617 page = OADDR_TO_PAGE(bucket); 618 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 619 /* Errno is set */ 620 return (-1); 621 if (wsize != size) { 622 errno = EFTYPE; 623 return (-1); 624 } 625 return (0); 626 } 627 628 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 629 /* 630 * Initialize a new bitmap page. Bitmap pages are left in memory 631 * once they are read in. 632 */ 633 extern int 634 __ibitmap(hashp, pnum, nbits, ndx) 635 HTAB *hashp; 636 int pnum, nbits, ndx; 637 { 638 u_int32_t *ip; 639 int clearbytes, clearints; 640 641 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 642 return (1); 643 hashp->nmaps++; 644 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 645 clearbytes = clearints << INT_TO_BYTE; 646 (void)memset((char *)ip, 0, clearbytes); 647 (void)memset(((char *)ip) + clearbytes, 0xFF, 648 hashp->BSIZE - clearbytes); 649 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 650 SETBIT(ip, 0); 651 hashp->BITMAPS[ndx] = (u_int16_t)pnum; 652 hashp->mapp[ndx] = ip; 653 return (0); 654 } 655 656 static u_int32_t 657 first_free(map) 658 u_int32_t map; 659 { 660 register u_int32_t i, mask; 661 662 mask = 0x1; 663 for (i = 0; i < BITS_PER_MAP; i++) { 664 if (!(mask & map)) 665 return (i); 666 mask = mask << 1; 667 } 668 return (i); 669 } 670 671 static u_int16_t 672 overflow_page(hashp) 673 HTAB *hashp; 674 { 675 register u_int32_t *freep = NULL; 676 register int max_free, offset, splitnum; 677 u_int16_t addr; 678 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 679 #ifdef DEBUG2 680 int tmp1, tmp2; 681 #endif 682 splitnum = hashp->OVFL_POINT; 683 max_free = hashp->SPARES[splitnum]; 684 685 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 686 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 687 688 /* Look through all the free maps to find the first free block */ 689 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 690 for ( i = first_page; i <= free_page; i++ ) { 691 if (!(freep = (u_int32_t *)hashp->mapp[i]) && 692 !(freep = fetch_bitmap(hashp, i))) 693 return (0); 694 if (i == free_page) 695 in_use_bits = free_bit; 696 else 697 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 698 699 if (i == first_page) { 700 bit = hashp->LAST_FREED & 701 ((hashp->BSIZE << BYTE_SHIFT) - 1); 702 j = bit / BITS_PER_MAP; 703 bit = bit & ~(BITS_PER_MAP - 1); 704 } else { 705 bit = 0; 706 j = 0; 707 } 708 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 709 if (freep[j] != ALL_SET) 710 goto found; 711 } 712 713 /* No Free Page Found */ 714 hashp->LAST_FREED = hashp->SPARES[splitnum]; 715 hashp->SPARES[splitnum]++; 716 offset = hashp->SPARES[splitnum] - 717 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 718 719 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 720 if (offset > SPLITMASK) { 721 if (++splitnum >= NCACHED) { 722 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 723 return (0); 724 } 725 hashp->OVFL_POINT = splitnum; 726 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 727 hashp->SPARES[splitnum-1]--; 728 offset = 1; 729 } 730 731 /* Check if we need to allocate a new bitmap page */ 732 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 733 free_page++; 734 if (free_page >= NCACHED) { 735 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 736 return (0); 737 } 738 /* 739 * This is tricky. The 1 indicates that you want the new page 740 * allocated with 1 clear bit. Actually, you are going to 741 * allocate 2 pages from this map. The first is going to be 742 * the map page, the second is the overflow page we were 743 * looking for. The init_bitmap routine automatically, sets 744 * the first bit of itself to indicate that the bitmap itself 745 * is in use. We would explicitly set the second bit, but 746 * don't have to if we tell init_bitmap not to leave it clear 747 * in the first place. 748 */ 749 if (__ibitmap(hashp, 750 (int)OADDR_OF(splitnum, offset), 1, free_page)) 751 return (0); 752 hashp->SPARES[splitnum]++; 753 #ifdef DEBUG2 754 free_bit = 2; 755 #endif 756 offset++; 757 if (offset > SPLITMASK) { 758 if (++splitnum >= NCACHED) { 759 (void)write(STDERR_FILENO, OVMSG, 760 sizeof(OVMSG) - 1); 761 return (0); 762 } 763 hashp->OVFL_POINT = splitnum; 764 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 765 hashp->SPARES[splitnum-1]--; 766 offset = 0; 767 } 768 } else { 769 /* 770 * Free_bit addresses the last used bit. Bump it to address 771 * the first available bit. 772 */ 773 free_bit++; 774 SETBIT(freep, free_bit); 775 } 776 777 /* Calculate address of the new overflow page */ 778 addr = OADDR_OF(splitnum, offset); 779 #ifdef DEBUG2 780 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 781 addr, free_bit, free_page); 782 #endif 783 return (addr); 784 785 found: 786 bit = bit + first_free(freep[j]); 787 SETBIT(freep, bit); 788 #ifdef DEBUG2 789 tmp1 = bit; 790 tmp2 = i; 791 #endif 792 /* 793 * Bits are addressed starting with 0, but overflow pages are addressed 794 * beginning at 1. Bit is a bit addressnumber, so we need to increment 795 * it to convert it to a page number. 796 */ 797 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 798 if (bit >= hashp->LAST_FREED) 799 hashp->LAST_FREED = bit - 1; 800 801 /* Calculate the split number for this page */ 802 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 803 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 804 if (offset >= SPLITMASK) 805 return (0); /* Out of overflow pages */ 806 addr = OADDR_OF(i, offset); 807 #ifdef DEBUG2 808 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 809 addr, tmp1, tmp2); 810 #endif 811 812 /* Allocate and return the overflow page */ 813 return (addr); 814 } 815 816 /* 817 * Mark this overflow page as free. 818 */ 819 extern void 820 __free_ovflpage(hashp, obufp) 821 HTAB *hashp; 822 BUFHEAD *obufp; 823 { 824 register u_int16_t addr; 825 u_int32_t *freep; 826 int bit_address, free_page, free_bit; 827 u_int16_t ndx; 828 829 addr = obufp->addr; 830 #ifdef DEBUG1 831 (void)fprintf(stderr, "Freeing %d\n", addr); 832 #endif 833 ndx = (((u_int16_t)addr) >> SPLITSHIFT); 834 bit_address = 835 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 836 if (bit_address < hashp->LAST_FREED) 837 hashp->LAST_FREED = bit_address; 838 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 839 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 840 841 if (!(freep = hashp->mapp[free_page])) 842 freep = fetch_bitmap(hashp, free_page); 843 #ifdef DEBUG 844 /* 845 * This had better never happen. It means we tried to read a bitmap 846 * that has already had overflow pages allocated off it, and we 847 * failed to read it from the file. 848 */ 849 if (!freep) 850 assert(0); 851 #endif 852 CLRBIT(freep, free_bit); 853 #ifdef DEBUG2 854 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 855 obufp->addr, free_bit, free_page); 856 #endif 857 __reclaim_buf(hashp, obufp); 858 } 859 860 /* 861 * Returns: 862 * 0 success 863 * -1 failure 864 */ 865 static int 866 open_temp(hashp) 867 HTAB *hashp; 868 { 869 sigset_t set, oset; 870 char namestr[] = "_hashXXXXXX"; 871 872 /* Block signals; make sure file goes away at process exit. */ 873 (void)sigfillset(&set); 874 (void)sigprocmask(SIG_BLOCK, &set, &oset); 875 if ((hashp->fp = mkstemp(namestr)) != -1) { 876 (void)unlink(namestr); 877 (void)fcntl(hashp->fp, F_SETFD, 1); 878 } 879 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 880 return (hashp->fp != -1 ? 0 : -1); 881 } 882 883 /* 884 * We have to know that the key will fit, but the last entry on the page is 885 * an overflow pair, so we need to shift things. 886 */ 887 static void 888 squeeze_key(sp, key, val) 889 u_int16_t *sp; 890 const DBT *key, *val; 891 { 892 register char *p; 893 u_int16_t free_space, n, off, pageno; 894 895 p = (char *)sp; 896 n = sp[0]; 897 free_space = FREESPACE(sp); 898 off = OFFSET(sp); 899 900 pageno = sp[n - 1]; 901 off -= key->size; 902 sp[n - 1] = off; 903 memmove(p + off, key->data, key->size); 904 off -= val->size; 905 sp[n] = off; 906 memmove(p + off, val->data, val->size); 907 sp[0] = n + 2; 908 sp[n + 1] = pageno; 909 sp[n + 2] = OVFLPAGE; 910 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 911 OFFSET(sp) = off; 912 } 913 914 static u_int32_t * 915 fetch_bitmap(hashp, ndx) 916 HTAB *hashp; 917 int ndx; 918 { 919 if (ndx >= hashp->nmaps) 920 return (NULL); 921 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 922 return (NULL); 923 if (__get_page(hashp, 924 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 925 free(hashp->mapp[ndx]); 926 return (NULL); 927 } 928 return (hashp->mapp[ndx]); 929 } 930 931 #ifdef DEBUG4 932 int 933 print_chain(addr) 934 int addr; 935 { 936 BUFHEAD *bufp; 937 short *bp, oaddr; 938 939 (void)fprintf(stderr, "%d ", addr); 940 bufp = __get_buf(hashp, addr, NULL, 0); 941 bp = (short *)bufp->page; 942 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 943 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 944 oaddr = bp[bp[0] - 1]; 945 (void)fprintf(stderr, "%d ", (int)oaddr); 946 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 947 bp = (short *)bufp->page; 948 } 949 (void)fprintf(stderr, "\n"); 950 } 951 #endif 952
Indexes created Fri Sep 26 08:10:20 GMT 2025