1 /*- 2 * Copyright (c) 1990, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Margo Seltzer. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)hash_page.c 8.7 (Berkeley) 8/16/94 33 * $FreeBSD: head/lib/libc/db/hash/hash_page.c 190500 2009-03-28 07:44:08Z delphij $ 34 */ 35 36 /* 37 * PACKAGE: hashing 38 * 39 * DESCRIPTION: 40 * Page manipulation for hashing package. 41 * 42 * ROUTINES: 43 * 44 * External 45 * __get_page 46 * __add_ovflpage 47 * Internal 48 * overflow_page 49 * open_temp 50 */ 51 52 #include "namespace.h" 53 #include <sys/param.h> 54 #include <sys/file.h> 55 56 #include <errno.h> 57 #include <fcntl.h> 58 #include <signal.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 #ifdef DEBUG 64 #include <assert.h> 65 #endif 66 #include "un-namespace.h" 67 68 #include <db.h> 69 #include "hash.h" 70 #include "page.h" 71 #include "extern.h" 72 73 static uint32_t *fetch_bitmap(HTAB *, int); 74 static uint32_t first_free(uint32_t); 75 static int open_temp(HTAB *); 76 static uint16_t overflow_page(HTAB *); 77 static void putpair(char *, const DBT *, const DBT *); 78 static void squeeze_key(uint16_t *, const DBT *, const DBT *); 79 static int ugly_split(HTAB *, uint32_t, BUFHEAD *, BUFHEAD *, int, int); 80 81 #define PAGE_INIT(P) { \ 82 ((uint16_t *)(P))[0] = 0; \ 83 ((uint16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(uint16_t); \ 84 ((uint16_t *)(P))[2] = hashp->BSIZE; \ 85 } 86 87 /* 88 * This is called AFTER we have verified that there is room on the page for 89 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 90 * stuff on. 91 */ 92 static void 93 putpair(char *p, const DBT *key, const DBT *val) 94 { 95 uint16_t *bp, n, off; 96 97 bp = (uint16_t *)p; 98 99 /* Enter the key first. */ 100 n = bp[0]; 101 102 off = OFFSET(bp) - key->size; 103 memmove(p + off, key->data, key->size); 104 bp[++n] = off; 105 106 /* Now the data. */ 107 off -= val->size; 108 memmove(p + off, val->data, val->size); 109 bp[++n] = off; 110 111 /* Adjust page info. */ 112 bp[0] = n; 113 bp[n + 1] = off - ((n + 3) * sizeof(uint16_t)); 114 bp[n + 2] = off; 115 } 116 117 /* 118 * Returns: 119 * 0 OK 120 * -1 error 121 */ 122 int 123 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx) 124 { 125 uint16_t *bp, newoff, pairlen; 126 int n; 127 128 bp = (uint16_t *)bufp->page; 129 n = bp[0]; 130 131 if (bp[ndx + 1] < REAL_KEY) 132 return (__big_delete(hashp, bufp)); 133 if (ndx != 1) 134 newoff = bp[ndx - 1]; 135 else 136 newoff = hashp->BSIZE; 137 pairlen = newoff - bp[ndx + 1]; 138 139 if (ndx != (n - 1)) { 140 /* Hard Case -- need to shuffle keys */ 141 int i; 142 char *src = bufp->page + (int)OFFSET(bp); 143 char *dst = src + (int)pairlen; 144 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 145 146 /* Now adjust the pointers */ 147 for (i = ndx + 2; i <= n; i += 2) { 148 if (bp[i + 1] == OVFLPAGE) { 149 bp[i - 2] = bp[i]; 150 bp[i - 1] = bp[i + 1]; 151 } else { 152 bp[i - 2] = bp[i] + pairlen; 153 bp[i - 1] = bp[i + 1] + pairlen; 154 } 155 } 156 if (ndx == hashp->cndx) { 157 /* 158 * We just removed pair we were "pointing" to. 159 * By moving back the cndx we ensure subsequent 160 * hash_seq() calls won't skip over any entries. 161 */ 162 hashp->cndx -= 2; 163 } 164 } 165 /* Finally adjust the page data */ 166 bp[n] = OFFSET(bp) + pairlen; 167 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(uint16_t); 168 bp[0] = n - 2; 169 hashp->NKEYS--; 170 171 bufp->flags |= BUF_MOD; 172 return (0); 173 } 174 /* 175 * Returns: 176 * 0 ==> OK 177 * -1 ==> Error 178 */ 179 int 180 __split_page(HTAB *hashp, uint32_t obucket, uint32_t nbucket) 181 { 182 BUFHEAD *new_bufp, *old_bufp; 183 uint16_t *ino; 184 char *np; 185 DBT key, val; 186 int n, ndx, retval; 187 uint16_t copyto, diff, off, moved; 188 char *op; 189 190 copyto = (uint16_t)hashp->BSIZE; 191 off = (uint16_t)hashp->BSIZE; 192 old_bufp = __get_buf(hashp, obucket, NULL, 0); 193 if (old_bufp == NULL) 194 return (-1); 195 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 196 if (new_bufp == NULL) 197 return (-1); 198 199 old_bufp->flags |= (BUF_MOD | BUF_PIN); 200 new_bufp->flags |= (BUF_MOD | BUF_PIN); 201 202 ino = (uint16_t *)(op = old_bufp->page); 203 np = new_bufp->page; 204 205 moved = 0; 206 207 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 208 if (ino[n + 1] < REAL_KEY) { 209 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 210 (int)copyto, (int)moved); 211 old_bufp->flags &= ~BUF_PIN; 212 new_bufp->flags &= ~BUF_PIN; 213 return (retval); 214 215 } 216 key.data = (unsigned char *)op + ino[n]; 217 key.size = off - ino[n]; 218 219 if (__call_hash(hashp, key.data, key.size) == obucket) { 220 /* Don't switch page */ 221 diff = copyto - off; 222 if (diff) { 223 copyto = ino[n + 1] + diff; 224 memmove(op + copyto, op + ino[n + 1], 225 off - ino[n + 1]); 226 ino[ndx] = copyto + ino[n] - ino[n + 1]; 227 ino[ndx + 1] = copyto; 228 } else 229 copyto = ino[n + 1]; 230 ndx += 2; 231 } else { 232 /* Switch page */ 233 val.data = (unsigned char *)op + ino[n + 1]; 234 val.size = ino[n] - ino[n + 1]; 235 putpair(np, &key, &val); 236 moved += 2; 237 } 238 239 off = ino[n + 1]; 240 } 241 242 /* Now clean up the page */ 243 ino[0] -= moved; 244 FREESPACE(ino) = copyto - sizeof(uint16_t) * (ino[0] + 3); 245 OFFSET(ino) = copyto; 246 247 #ifdef DEBUG3 248 fprintf(stderr, "split %d/%d\n", 249 ((uint16_t *)np)[0] / 2, 250 ((uint16_t *)op)[0] / 2); 251 #endif 252 /* unpin both pages */ 253 old_bufp->flags &= ~BUF_PIN; 254 new_bufp->flags &= ~BUF_PIN; 255 return (0); 256 } 257 258 /* 259 * Called when we encounter an overflow or big key/data page during split 260 * handling. This is special cased since we have to begin checking whether 261 * the key/data pairs fit on their respective pages and because we may need 262 * overflow pages for both the old and new pages. 263 * 264 * The first page might be a page with regular key/data pairs in which case 265 * we have a regular overflow condition and just need to go on to the next 266 * page or it might be a big key/data pair in which case we need to fix the 267 * big key/data pair. 268 * 269 * Returns: 270 * 0 ==> success 271 * -1 ==> failure 272 */ 273 static int 274 ugly_split(HTAB *hashp, 275 uint32_t obucket, /* Same as __split_page. */ 276 BUFHEAD *old_bufp, 277 BUFHEAD *new_bufp, 278 int copyto, /* First byte on page which contains key/data values. */ 279 int moved) /* Number of pairs moved to new page. */ 280 { 281 BUFHEAD *bufp; /* Buffer header for ino */ 282 uint16_t *ino; /* Page keys come off of */ 283 uint16_t *np; /* New page */ 284 uint16_t *op; /* Page keys go on to if they aren't moving */ 285 286 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 287 DBT key, val; 288 SPLIT_RETURN ret; 289 uint16_t n, off, ov_addr, scopyto; 290 char *cino; /* Character value of ino */ 291 292 bufp = old_bufp; 293 ino = (uint16_t *)old_bufp->page; 294 np = (uint16_t *)new_bufp->page; 295 op = (uint16_t *)old_bufp->page; 296 last_bfp = NULL; 297 scopyto = (uint16_t)copyto; /* ANSI */ 298 299 n = ino[0] - 1; 300 while (n < ino[0]) { 301 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 302 if (__big_split(hashp, old_bufp, 303 new_bufp, bufp, bufp->addr, obucket, &ret)) 304 return (-1); 305 old_bufp = ret.oldp; 306 if (!old_bufp) 307 return (-1); 308 op = (uint16_t *)old_bufp->page; 309 new_bufp = ret.newp; 310 if (!new_bufp) 311 return (-1); 312 np = (uint16_t *)new_bufp->page; 313 bufp = ret.nextp; 314 if (!bufp) 315 return (0); 316 cino = (char *)bufp->page; 317 ino = (uint16_t *)cino; 318 last_bfp = ret.nextp; 319 } else if (ino[n + 1] == OVFLPAGE) { 320 ov_addr = ino[n]; 321 /* 322 * Fix up the old page -- the extra 2 are the fields 323 * which contained the overflow information. 324 */ 325 ino[0] -= (moved + 2); 326 FREESPACE(ino) = 327 scopyto - sizeof(uint16_t) * (ino[0] + 3); 328 OFFSET(ino) = scopyto; 329 330 bufp = __get_buf(hashp, ov_addr, bufp, 0); 331 if (!bufp) 332 return (-1); 333 334 ino = (uint16_t *)bufp->page; 335 n = 1; 336 scopyto = hashp->BSIZE; 337 moved = 0; 338 339 if (last_bfp) 340 __free_ovflpage(hashp, last_bfp); 341 last_bfp = bufp; 342 } 343 /* Move regular sized pairs of there are any */ 344 off = hashp->BSIZE; 345 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 346 cino = (char *)ino; 347 key.data = (unsigned char *)cino + ino[n]; 348 key.size = off - ino[n]; 349 val.data = (unsigned char *)cino + ino[n + 1]; 350 val.size = ino[n] - ino[n + 1]; 351 off = ino[n + 1]; 352 353 if (__call_hash(hashp, key.data, key.size) == obucket) { 354 /* Keep on old page */ 355 if (PAIRFITS(op, (&key), (&val))) 356 putpair((char *)op, &key, &val); 357 else { 358 old_bufp = 359 __add_ovflpage(hashp, old_bufp); 360 if (!old_bufp) 361 return (-1); 362 op = (uint16_t *)old_bufp->page; 363 putpair((char *)op, &key, &val); 364 } 365 old_bufp->flags |= BUF_MOD; 366 } else { 367 /* Move to new page */ 368 if (PAIRFITS(np, (&key), (&val))) 369 putpair((char *)np, &key, &val); 370 else { 371 new_bufp = 372 __add_ovflpage(hashp, new_bufp); 373 if (!new_bufp) 374 return (-1); 375 np = (uint16_t *)new_bufp->page; 376 putpair((char *)np, &key, &val); 377 } 378 new_bufp->flags |= BUF_MOD; 379 } 380 } 381 } 382 if (last_bfp) 383 __free_ovflpage(hashp, last_bfp); 384 return (0); 385 } 386 387 /* 388 * Add the given pair to the page 389 * 390 * Returns: 391 * 0 ==> OK 392 * 1 ==> failure 393 */ 394 int 395 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val) 396 { 397 uint16_t *bp, *sop; 398 int do_expand; 399 400 bp = (uint16_t *)bufp->page; 401 do_expand = 0; 402 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 403 /* Exception case */ 404 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 405 /* This is the last page of a big key/data pair 406 and we need to add another page */ 407 break; 408 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 409 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 410 if (!bufp) 411 return (-1); 412 bp = (uint16_t *)bufp->page; 413 } else if (bp[bp[0]] != OVFLPAGE) { 414 /* Short key/data pairs, no more pages */ 415 break; 416 } else { 417 /* Try to squeeze key on this page */ 418 if (bp[2] >= REAL_KEY && 419 FREESPACE(bp) >= PAIRSIZE(key, val)) { 420 squeeze_key(bp, key, val); 421 goto stats; 422 } else { 423 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 424 if (!bufp) 425 return (-1); 426 bp = (uint16_t *)bufp->page; 427 } 428 } 429 430 if (PAIRFITS(bp, key, val)) 431 putpair(bufp->page, key, val); 432 else { 433 do_expand = 1; 434 bufp = __add_ovflpage(hashp, bufp); 435 if (!bufp) 436 return (-1); 437 sop = (uint16_t *)bufp->page; 438 439 if (PAIRFITS(sop, key, val)) 440 putpair((char *)sop, key, val); 441 else 442 if (__big_insert(hashp, bufp, key, val)) 443 return (-1); 444 } 445 stats: 446 bufp->flags |= BUF_MOD; 447 /* 448 * If the average number of keys per bucket exceeds the fill factor, 449 * expand the table. 450 */ 451 hashp->NKEYS++; 452 if (do_expand || 453 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 454 return (__expand_table(hashp)); 455 return (0); 456 } 457 458 /* 459 * 460 * Returns: 461 * pointer on success 462 * NULL on error 463 */ 464 BUFHEAD * 465 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp) 466 { 467 uint16_t *sp, ndx, ovfl_num; 468 #ifdef DEBUG1 469 int tmp1, tmp2; 470 #endif 471 sp = (uint16_t *)bufp->page; 472 473 /* Check if we are dynamically determining the fill factor */ 474 if (hashp->FFACTOR == DEF_FFACTOR) { 475 hashp->FFACTOR = sp[0] >> 1; 476 if (hashp->FFACTOR < MIN_FFACTOR) 477 hashp->FFACTOR = MIN_FFACTOR; 478 } 479 bufp->flags |= BUF_MOD; 480 ovfl_num = overflow_page(hashp); 481 #ifdef DEBUG1 482 tmp1 = bufp->addr; 483 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 484 #endif 485 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 486 return (NULL); 487 bufp->ovfl->flags |= BUF_MOD; 488 #ifdef DEBUG1 489 fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 490 tmp1, tmp2, bufp->ovfl->addr); 491 #endif 492 ndx = sp[0]; 493 /* 494 * Since a pair is allocated on a page only if there's room to add 495 * an overflow page, we know that the OVFL information will fit on 496 * the page. 497 */ 498 sp[ndx + 4] = OFFSET(sp); 499 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 500 sp[ndx + 1] = ovfl_num; 501 sp[ndx + 2] = OVFLPAGE; 502 sp[0] = ndx + 2; 503 #ifdef HASH_STATISTICS 504 hash_overflows++; 505 #endif 506 return (bufp->ovfl); 507 } 508 509 /* 510 * Returns: 511 * 0 indicates SUCCESS 512 * -1 indicates FAILURE 513 */ 514 int 515 __get_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_disk, 516 int is_bitmap) 517 { 518 int fd, page, size, rsize; 519 uint16_t *bp; 520 521 fd = hashp->fp; 522 size = hashp->BSIZE; 523 524 if ((fd == -1) || !is_disk) { 525 PAGE_INIT(p); 526 return (0); 527 } 528 if (is_bucket) 529 page = BUCKET_TO_PAGE(bucket); 530 else 531 page = OADDR_TO_PAGE(bucket); 532 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 533 return (-1); 534 bp = (uint16_t *)p; 535 if (!rsize) 536 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 537 else 538 if (rsize != size) { 539 errno = EFTYPE; 540 return (-1); 541 } 542 if (!is_bitmap && !bp[0]) { 543 PAGE_INIT(p); 544 } else 545 if (hashp->LORDER != BYTE_ORDER) { 546 int i, max; 547 548 if (is_bitmap) { 549 max = hashp->BSIZE >> 2; /* divide by 4 */ 550 for (i = 0; i < max; i++) 551 M_32_SWAP(((int *)p)[i]); 552 } else { 553 M_16_SWAP(bp[0]); 554 max = bp[0] + 2; 555 for (i = 1; i <= max; i++) 556 M_16_SWAP(bp[i]); 557 } 558 } 559 return (0); 560 } 561 562 /* 563 * Write page p to disk 564 * 565 * Returns: 566 * 0 ==> OK 567 * -1 ==>failure 568 */ 569 int 570 __put_page(HTAB *hashp, char *p, uint32_t bucket, int is_bucket, int is_bitmap) 571 { 572 int fd, page, size, wsize; 573 574 size = hashp->BSIZE; 575 if ((hashp->fp == -1) && open_temp(hashp)) 576 return (-1); 577 fd = hashp->fp; 578 579 if (hashp->LORDER != BYTE_ORDER) { 580 int i, max; 581 582 if (is_bitmap) { 583 max = hashp->BSIZE >> 2; /* divide by 4 */ 584 for (i = 0; i < max; i++) 585 M_32_SWAP(((int *)p)[i]); 586 } else { 587 max = ((uint16_t *)p)[0] + 2; 588 for (i = 0; i <= max; i++) 589 M_16_SWAP(((uint16_t *)p)[i]); 590 } 591 } 592 if (is_bucket) 593 page = BUCKET_TO_PAGE(bucket); 594 else 595 page = OADDR_TO_PAGE(bucket); 596 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 597 /* Errno is set */ 598 return (-1); 599 if (wsize != size) { 600 errno = EFTYPE; 601 return (-1); 602 } 603 return (0); 604 } 605 606 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 607 /* 608 * Initialize a new bitmap page. Bitmap pages are left in memory 609 * once they are read in. 610 */ 611 int 612 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx) 613 { 614 uint32_t *ip; 615 int clearbytes, clearints; 616 617 if ((ip = (uint32_t *)malloc(hashp->BSIZE)) == NULL) 618 return (1); 619 hashp->nmaps++; 620 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 621 clearbytes = clearints << INT_TO_BYTE; 622 memset((char *)ip, 0, clearbytes); 623 memset(((char *)ip) + clearbytes, 0xFF, 624 hashp->BSIZE - clearbytes); 625 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 626 SETBIT(ip, 0); 627 hashp->BITMAPS[ndx] = (uint16_t)pnum; 628 hashp->mapp[ndx] = ip; 629 return (0); 630 } 631 632 static uint32_t 633 first_free(uint32_t map) 634 { 635 uint32_t i, mask; 636 637 mask = 0x1; 638 for (i = 0; i < BITS_PER_MAP; i++) { 639 if (!(mask & map)) 640 return (i); 641 mask = mask << 1; 642 } 643 return (i); 644 } 645 646 static uint16_t 647 overflow_page(HTAB *hashp) 648 { 649 uint32_t *freep; 650 int max_free, offset, splitnum; 651 uint16_t addr; 652 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 653 #ifdef DEBUG2 654 int tmp1, tmp2; 655 #endif 656 splitnum = hashp->OVFL_POINT; 657 max_free = hashp->SPARES[splitnum]; 658 659 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 660 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 661 662 /* Look through all the free maps to find the first free block */ 663 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 664 for ( i = first_page; i <= free_page; i++ ) { 665 if (!(freep = (uint32_t *)hashp->mapp[i]) && 666 !(freep = fetch_bitmap(hashp, i))) 667 return (0); 668 if (i == free_page) 669 in_use_bits = free_bit; 670 else 671 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 672 673 if (i == first_page) { 674 bit = hashp->LAST_FREED & 675 ((hashp->BSIZE << BYTE_SHIFT) - 1); 676 j = bit / BITS_PER_MAP; 677 bit = bit & ~(BITS_PER_MAP - 1); 678 } else { 679 bit = 0; 680 j = 0; 681 } 682 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 683 if (freep[j] != ALL_SET) 684 goto found; 685 } 686 687 /* No Free Page Found */ 688 hashp->LAST_FREED = hashp->SPARES[splitnum]; 689 hashp->SPARES[splitnum]++; 690 offset = hashp->SPARES[splitnum] - 691 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 692 693 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 694 if (offset > SPLITMASK) { 695 if (++splitnum >= NCACHED) { 696 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 697 errno = EFBIG; 698 return (0); 699 } 700 hashp->OVFL_POINT = splitnum; 701 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 702 hashp->SPARES[splitnum-1]--; 703 offset = 1; 704 } 705 706 /* Check if we need to allocate a new bitmap page */ 707 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 708 free_page++; 709 if (free_page >= NCACHED) { 710 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 711 errno = EFBIG; 712 return (0); 713 } 714 /* 715 * This is tricky. The 1 indicates that you want the new page 716 * allocated with 1 clear bit. Actually, you are going to 717 * allocate 2 pages from this map. The first is going to be 718 * the map page, the second is the overflow page we were 719 * looking for. The init_bitmap routine automatically, sets 720 * the first bit of itself to indicate that the bitmap itself 721 * is in use. We would explicitly set the second bit, but 722 * don't have to if we tell init_bitmap not to leave it clear 723 * in the first place. 724 */ 725 if (__ibitmap(hashp, 726 (int)OADDR_OF(splitnum, offset), 1, free_page)) 727 return (0); 728 hashp->SPARES[splitnum]++; 729 #ifdef DEBUG2 730 free_bit = 2; 731 #endif 732 offset++; 733 if (offset > SPLITMASK) { 734 if (++splitnum >= NCACHED) { 735 _write(STDERR_FILENO, OVMSG, 736 sizeof(OVMSG) - 1); 737 errno = EFBIG; 738 return (0); 739 } 740 hashp->OVFL_POINT = splitnum; 741 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 742 hashp->SPARES[splitnum-1]--; 743 offset = 0; 744 } 745 } else { 746 /* 747 * Free_bit addresses the last used bit. Bump it to address 748 * the first available bit. 749 */ 750 free_bit++; 751 SETBIT(freep, free_bit); 752 } 753 754 /* Calculate address of the new overflow page */ 755 addr = OADDR_OF(splitnum, offset); 756 #ifdef DEBUG2 757 fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 758 addr, free_bit, free_page); 759 #endif 760 return (addr); 761 762 found: 763 bit = bit + first_free(freep[j]); 764 SETBIT(freep, bit); 765 #ifdef DEBUG2 766 tmp1 = bit; 767 tmp2 = i; 768 #endif 769 /* 770 * Bits are addressed starting with 0, but overflow pages are addressed 771 * beginning at 1. Bit is a bit addressnumber, so we need to increment 772 * it to convert it to a page number. 773 */ 774 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 775 if (bit >= hashp->LAST_FREED) 776 hashp->LAST_FREED = bit - 1; 777 778 /* Calculate the split number for this page */ 779 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 780 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 781 if (offset >= SPLITMASK) { 782 _write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 783 errno = EFBIG; 784 return (0); /* Out of overflow pages */ 785 } 786 addr = OADDR_OF(i, offset); 787 #ifdef DEBUG2 788 fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 789 addr, tmp1, tmp2); 790 #endif 791 792 /* Allocate and return the overflow page */ 793 return (addr); 794 } 795 796 /* 797 * Mark this overflow page as free. 798 */ 799 void 800 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp) 801 { 802 uint16_t addr; 803 uint32_t *freep; 804 int bit_address, free_page, free_bit; 805 uint16_t ndx; 806 807 addr = obufp->addr; 808 #ifdef DEBUG1 809 fprintf(stderr, "Freeing %d\n", addr); 810 #endif 811 ndx = (((uint16_t)addr) >> SPLITSHIFT); 812 bit_address = 813 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 814 if (bit_address < hashp->LAST_FREED) 815 hashp->LAST_FREED = bit_address; 816 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 817 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 818 819 if (!(freep = hashp->mapp[free_page])) 820 freep = fetch_bitmap(hashp, free_page); 821 #ifdef DEBUG 822 /* 823 * This had better never happen. It means we tried to read a bitmap 824 * that has already had overflow pages allocated off it, and we 825 * failed to read it from the file. 826 */ 827 if (!freep) 828 assert(0); 829 #endif 830 CLRBIT(freep, free_bit); 831 #ifdef DEBUG2 832 fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 833 obufp->addr, free_bit, free_page); 834 #endif 835 __reclaim_buf(hashp, obufp); 836 } 837 838 /* 839 * Returns: 840 * 0 success 841 * -1 failure 842 */ 843 static int 844 open_temp(HTAB *hashp) 845 { 846 sigset_t set, oset; 847 int len; 848 char *envtmp = NULL; 849 char path[MAXPATHLEN]; 850 851 if (issetugid() == 0) 852 envtmp = getenv("TMPDIR"); 853 len = snprintf(path, 854 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp"); 855 if (len < 0 || len >= (int)sizeof(path)) { 856 errno = ENAMETOOLONG; 857 return (-1); 858 } 859 860 /* Block signals; make sure file goes away at process exit. */ 861 sigfillset(&set); 862 _sigprocmask(SIG_BLOCK, &set, &oset); 863 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1) { 864 _unlink(path); 865 _fcntl(hashp->fp, F_SETFD, 1); 866 } 867 _sigprocmask(SIG_SETMASK, &oset, NULL); 868 return (hashp->fp != -1 ? 0 : -1); 869 } 870 871 /* 872 * We have to know that the key will fit, but the last entry on the page is 873 * an overflow pair, so we need to shift things. 874 */ 875 static void 876 squeeze_key(uint16_t *sp, const DBT *key, const DBT *val) 877 { 878 char *p; 879 uint16_t free_space, n, off, pageno; 880 881 p = (char *)sp; 882 n = sp[0]; 883 free_space = FREESPACE(sp); 884 off = OFFSET(sp); 885 886 pageno = sp[n - 1]; 887 off -= key->size; 888 sp[n - 1] = off; 889 memmove(p + off, key->data, key->size); 890 off -= val->size; 891 sp[n] = off; 892 memmove(p + off, val->data, val->size); 893 sp[0] = n + 2; 894 sp[n + 1] = pageno; 895 sp[n + 2] = OVFLPAGE; 896 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 897 OFFSET(sp) = off; 898 } 899 900 static uint32_t * 901 fetch_bitmap(HTAB *hashp, int ndx) 902 { 903 if (ndx >= hashp->nmaps) 904 return (NULL); 905 if ((hashp->mapp[ndx] = (uint32_t *)malloc(hashp->BSIZE)) == NULL) 906 return (NULL); 907 if (__get_page(hashp, 908 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 909 free(hashp->mapp[ndx]); 910 return (NULL); 911 } 912 return (hashp->mapp[ndx]); 913 } 914 915 #ifdef DEBUG4 916 int 917 print_chain(int addr) 918 { 919 BUFHEAD *bufp; 920 short *bp, oaddr; 921 922 fprintf(stderr, "%d ", addr); 923 bufp = __get_buf(hashp, addr, NULL, 0); 924 bp = (short *)bufp->page; 925 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 926 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 927 oaddr = bp[bp[0] - 1]; 928 fprintf(stderr, "%d ", (int)oaddr); 929 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 930 bp = (short *)bufp->page; 931 } 932 fprintf(stderr, "\n"); 933 } 934 #endif 935