hash_page.c revision 190487
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 * 4. 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 33#if defined(LIBC_SCCS) && !defined(lint) 34static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94"; 35#endif /* LIBC_SCCS and not lint */ 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: head/lib/libc/db/hash/hash_page.c 190487 2009-03-28 06:12:39Z delphij $"); 38 39/* 40 * PACKAGE: hashing 41 * 42 * DESCRIPTION: 43 * Page manipulation for hashing package. 44 * 45 * ROUTINES: 46 * 47 * External 48 * __get_page 49 * __add_ovflpage 50 * Internal 51 * overflow_page 52 * open_temp 53 */ 54 55#include "namespace.h" 56#include <sys/param.h> 57 58#include <errno.h> 59#include <fcntl.h> 60#include <signal.h> 61#include <stdio.h> 62#include <stdlib.h> 63#include <string.h> 64#include <unistd.h> 65#ifdef DEBUG 66#include <assert.h> 67#endif 68#include "un-namespace.h" 69 70#include <db.h> 71#include "hash.h" 72#include "page.h" 73#include "extern.h" 74 75static u_int32_t *fetch_bitmap(HTAB *, int); 76static u_int32_t first_free(u_int32_t); 77static int open_temp(HTAB *); 78static u_int16_t overflow_page(HTAB *); 79static void putpair(char *, const DBT *, const DBT *); 80static void squeeze_key(u_int16_t *, const DBT *, const DBT *); 81static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int); 82 83#define PAGE_INIT(P) { \ 84 ((u_int16_t *)(P))[0] = 0; \ 85 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \ 86 ((u_int16_t *)(P))[2] = hashp->BSIZE; \ 87} 88 89/* 90 * This is called AFTER we have verified that there is room on the page for 91 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 92 * stuff on. 93 */ 94static void 95putpair(char *p, const DBT *key, const DBT *val) 96{ 97 u_int16_t *bp, n, off; 98 99 bp = (u_int16_t *)p; 100 101 /* Enter the key first. */ 102 n = bp[0]; 103 104 off = OFFSET(bp) - key->size; 105 memmove(p + off, key->data, key->size); 106 bp[++n] = off; 107 108 /* Now the data. */ 109 off -= val->size; 110 memmove(p + off, val->data, val->size); 111 bp[++n] = off; 112 113 /* Adjust page info. */ 114 bp[0] = n; 115 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t)); 116 bp[n + 2] = off; 117} 118 119/* 120 * Returns: 121 * 0 OK 122 * -1 error 123 */ 124int 125__delpair(HTAB *hashp, BUFHEAD *bufp, int ndx) 126{ 127 u_int16_t *bp, newoff; 128 int n; 129 u_int16_t pairlen; 130 131 bp = (u_int16_t *)bufp->page; 132 n = bp[0]; 133 134 if (bp[ndx + 1] < REAL_KEY) 135 return (__big_delete(hashp, bufp)); 136 if (ndx != 1) 137 newoff = bp[ndx - 1]; 138 else 139 newoff = hashp->BSIZE; 140 pairlen = newoff - bp[ndx + 1]; 141 142 if (ndx != (n - 1)) { 143 /* Hard Case -- need to shuffle keys */ 144 int i; 145 char *src = bufp->page + (int)OFFSET(bp); 146 char *dst = src + (int)pairlen; 147 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 148 149 /* Now adjust the pointers */ 150 for (i = ndx + 2; i <= n; i += 2) { 151 if (bp[i + 1] == OVFLPAGE) { 152 bp[i - 2] = bp[i]; 153 bp[i - 1] = bp[i + 1]; 154 } else { 155 bp[i - 2] = bp[i] + pairlen; 156 bp[i - 1] = bp[i + 1] + pairlen; 157 } 158 } 159 } 160 /* Finally adjust the page data */ 161 bp[n] = OFFSET(bp) + pairlen; 162 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t); 163 bp[0] = n - 2; 164 hashp->NKEYS--; 165 166 bufp->flags |= BUF_MOD; 167 return (0); 168} 169/* 170 * Returns: 171 * 0 ==> OK 172 * -1 ==> Error 173 */ 174int 175__split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket) 176{ 177 BUFHEAD *new_bufp, *old_bufp; 178 u_int16_t *ino; 179 char *np; 180 DBT key, val; 181 int n, ndx, retval; 182 u_int16_t copyto, diff, off, moved; 183 char *op; 184 185 copyto = (u_int16_t)hashp->BSIZE; 186 off = (u_int16_t)hashp->BSIZE; 187 old_bufp = __get_buf(hashp, obucket, NULL, 0); 188 if (old_bufp == NULL) 189 return (-1); 190 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 191 if (new_bufp == NULL) 192 return (-1); 193 194 old_bufp->flags |= (BUF_MOD | BUF_PIN); 195 new_bufp->flags |= (BUF_MOD | BUF_PIN); 196 197 ino = (u_int16_t *)(op = old_bufp->page); 198 np = new_bufp->page; 199 200 moved = 0; 201 202 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 203 if (ino[n + 1] < REAL_KEY) { 204 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 205 (int)copyto, (int)moved); 206 old_bufp->flags &= ~BUF_PIN; 207 new_bufp->flags &= ~BUF_PIN; 208 return (retval); 209 210 } 211 key.data = (u_char *)op + ino[n]; 212 key.size = off - ino[n]; 213 214 if (__call_hash(hashp, key.data, key.size) == obucket) { 215 /* Don't switch page */ 216 diff = copyto - off; 217 if (diff) { 218 copyto = ino[n + 1] + diff; 219 memmove(op + copyto, op + ino[n + 1], 220 off - ino[n + 1]); 221 ino[ndx] = copyto + ino[n] - ino[n + 1]; 222 ino[ndx + 1] = copyto; 223 } else 224 copyto = ino[n + 1]; 225 ndx += 2; 226 } else { 227 /* Switch page */ 228 val.data = (u_char *)op + ino[n + 1]; 229 val.size = ino[n] - ino[n + 1]; 230 putpair(np, &key, &val); 231 moved += 2; 232 } 233 234 off = ino[n + 1]; 235 } 236 237 /* Now clean up the page */ 238 ino[0] -= moved; 239 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3); 240 OFFSET(ino) = copyto; 241 242#ifdef DEBUG3 243 (void)fprintf(stderr, "split %d/%d\n", 244 ((u_int16_t *)np)[0] / 2, 245 ((u_int16_t *)op)[0] / 2); 246#endif 247 /* unpin both pages */ 248 old_bufp->flags &= ~BUF_PIN; 249 new_bufp->flags &= ~BUF_PIN; 250 return (0); 251} 252 253/* 254 * Called when we encounter an overflow or big key/data page during split 255 * handling. This is special cased since we have to begin checking whether 256 * the key/data pairs fit on their respective pages and because we may need 257 * overflow pages for both the old and new pages. 258 * 259 * The first page might be a page with regular key/data pairs in which case 260 * we have a regular overflow condition and just need to go on to the next 261 * page or it might be a big key/data pair in which case we need to fix the 262 * big key/data pair. 263 * 264 * Returns: 265 * 0 ==> success 266 * -1 ==> failure 267 */ 268static int 269ugly_split(HTAB *hashp, 270 u_int32_t obucket, /* Same as __split_page. */ 271 BUFHEAD *old_bufp, 272 BUFHEAD *new_bufp, 273 int copyto, /* First byte on page which contains key/data values. */ 274 int moved) /* Number of pairs moved to new page. */ 275{ 276 BUFHEAD *bufp; /* Buffer header for ino */ 277 u_int16_t *ino; /* Page keys come off of */ 278 u_int16_t *np; /* New page */ 279 u_int16_t *op; /* Page keys go on to if they aren't moving */ 280 281 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 282 DBT key, val; 283 SPLIT_RETURN ret; 284 u_int16_t n, off, ov_addr, scopyto; 285 char *cino; /* Character value of ino */ 286 287 bufp = old_bufp; 288 ino = (u_int16_t *)old_bufp->page; 289 np = (u_int16_t *)new_bufp->page; 290 op = (u_int16_t *)old_bufp->page; 291 last_bfp = NULL; 292 scopyto = (u_int16_t)copyto; /* ANSI */ 293 294 n = ino[0] - 1; 295 while (n < ino[0]) { 296 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 297 if (__big_split(hashp, old_bufp, 298 new_bufp, bufp, bufp->addr, obucket, &ret)) 299 return (-1); 300 old_bufp = ret.oldp; 301 if (!old_bufp) 302 return (-1); 303 op = (u_int16_t *)old_bufp->page; 304 new_bufp = ret.newp; 305 if (!new_bufp) 306 return (-1); 307 np = (u_int16_t *)new_bufp->page; 308 bufp = ret.nextp; 309 if (!bufp) 310 return (0); 311 cino = (char *)bufp->page; 312 ino = (u_int16_t *)cino; 313 last_bfp = ret.nextp; 314 } else if (ino[n + 1] == OVFLPAGE) { 315 ov_addr = ino[n]; 316 /* 317 * Fix up the old page -- the extra 2 are the fields 318 * which contained the overflow information. 319 */ 320 ino[0] -= (moved + 2); 321 FREESPACE(ino) = 322 scopyto - sizeof(u_int16_t) * (ino[0] + 3); 323 OFFSET(ino) = scopyto; 324 325 bufp = __get_buf(hashp, ov_addr, bufp, 0); 326 if (!bufp) 327 return (-1); 328 329 ino = (u_int16_t *)bufp->page; 330 n = 1; 331 scopyto = hashp->BSIZE; 332 moved = 0; 333 334 if (last_bfp) 335 __free_ovflpage(hashp, last_bfp); 336 last_bfp = bufp; 337 } 338 /* Move regular sized pairs of there are any */ 339 off = hashp->BSIZE; 340 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 341 cino = (char *)ino; 342 key.data = (u_char *)cino + ino[n]; 343 key.size = off - ino[n]; 344 val.data = (u_char *)cino + ino[n + 1]; 345 val.size = ino[n] - ino[n + 1]; 346 off = ino[n + 1]; 347 348 if (__call_hash(hashp, key.data, key.size) == obucket) { 349 /* Keep on old page */ 350 if (PAIRFITS(op, (&key), (&val))) 351 putpair((char *)op, &key, &val); 352 else { 353 old_bufp = 354 __add_ovflpage(hashp, old_bufp); 355 if (!old_bufp) 356 return (-1); 357 op = (u_int16_t *)old_bufp->page; 358 putpair((char *)op, &key, &val); 359 } 360 old_bufp->flags |= BUF_MOD; 361 } else { 362 /* Move to new page */ 363 if (PAIRFITS(np, (&key), (&val))) 364 putpair((char *)np, &key, &val); 365 else { 366 new_bufp = 367 __add_ovflpage(hashp, new_bufp); 368 if (!new_bufp) 369 return (-1); 370 np = (u_int16_t *)new_bufp->page; 371 putpair((char *)np, &key, &val); 372 } 373 new_bufp->flags |= BUF_MOD; 374 } 375 } 376 } 377 if (last_bfp) 378 __free_ovflpage(hashp, last_bfp); 379 return (0); 380} 381 382/* 383 * Add the given pair to the page 384 * 385 * Returns: 386 * 0 ==> OK 387 * 1 ==> failure 388 */ 389int 390__addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val) 391{ 392 u_int16_t *bp, *sop; 393 int do_expand; 394 395 bp = (u_int16_t *)bufp->page; 396 do_expand = 0; 397 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 398 /* Exception case */ 399 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 400 /* This is the last page of a big key/data pair 401 and we need to add another page */ 402 break; 403 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 404 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 405 if (!bufp) 406 return (-1); 407 bp = (u_int16_t *)bufp->page; 408 } else 409 /* Try to squeeze key on this page */ 410 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 411 squeeze_key(bp, key, val); 412 return (0); 413 } else { 414 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 415 if (!bufp) 416 return (-1); 417 bp = (u_int16_t *)bufp->page; 418 } 419 420 if (PAIRFITS(bp, key, val)) 421 putpair(bufp->page, key, val); 422 else { 423 do_expand = 1; 424 bufp = __add_ovflpage(hashp, bufp); 425 if (!bufp) 426 return (-1); 427 sop = (u_int16_t *)bufp->page; 428 429 if (PAIRFITS(sop, key, val)) 430 putpair((char *)sop, key, val); 431 else 432 if (__big_insert(hashp, bufp, key, val)) 433 return (-1); 434 } 435 bufp->flags |= BUF_MOD; 436 /* 437 * If the average number of keys per bucket exceeds the fill factor, 438 * expand the table. 439 */ 440 hashp->NKEYS++; 441 if (do_expand || 442 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 443 return (__expand_table(hashp)); 444 return (0); 445} 446 447/* 448 * 449 * Returns: 450 * pointer on success 451 * NULL on error 452 */ 453BUFHEAD * 454__add_ovflpage(HTAB *hashp, BUFHEAD *bufp) 455{ 456 u_int16_t *sp; 457 u_int16_t ndx, ovfl_num; 458#ifdef DEBUG1 459 int tmp1, tmp2; 460#endif 461 sp = (u_int16_t *)bufp->page; 462 463 /* Check if we are dynamically determining the fill factor */ 464 if (hashp->FFACTOR == DEF_FFACTOR) { 465 hashp->FFACTOR = sp[0] >> 1; 466 if (hashp->FFACTOR < MIN_FFACTOR) 467 hashp->FFACTOR = MIN_FFACTOR; 468 } 469 bufp->flags |= BUF_MOD; 470 ovfl_num = overflow_page(hashp); 471#ifdef DEBUG1 472 tmp1 = bufp->addr; 473 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 474#endif 475 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 476 return (NULL); 477 bufp->ovfl->flags |= BUF_MOD; 478#ifdef DEBUG1 479 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 480 tmp1, tmp2, bufp->ovfl->addr); 481#endif 482 ndx = sp[0]; 483 /* 484 * Since a pair is allocated on a page only if there's room to add 485 * an overflow page, we know that the OVFL information will fit on 486 * the page. 487 */ 488 sp[ndx + 4] = OFFSET(sp); 489 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 490 sp[ndx + 1] = ovfl_num; 491 sp[ndx + 2] = OVFLPAGE; 492 sp[0] = ndx + 2; 493#ifdef HASH_STATISTICS 494 hash_overflows++; 495#endif 496 return (bufp->ovfl); 497} 498 499/* 500 * Returns: 501 * 0 indicates SUCCESS 502 * -1 indicates FAILURE 503 */ 504int 505__get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk, 506 int is_bitmap) 507{ 508 int fd, page, size; 509 int rsize; 510 u_int16_t *bp; 511 512 fd = hashp->fp; 513 size = hashp->BSIZE; 514 515 if ((fd == -1) || !is_disk) { 516 PAGE_INIT(p); 517 return (0); 518 } 519 if (is_bucket) 520 page = BUCKET_TO_PAGE(bucket); 521 else 522 page = OADDR_TO_PAGE(bucket); 523 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 524 return (-1); 525 bp = (u_int16_t *)p; 526 if (!rsize) 527 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 528 else 529 if (rsize != size) { 530 errno = EFTYPE; 531 return (-1); 532 } 533 if (!is_bitmap && !bp[0]) { 534 PAGE_INIT(p); 535 } else 536 if (hashp->LORDER != BYTE_ORDER) { 537 int i, max; 538 539 if (is_bitmap) { 540 max = hashp->BSIZE >> 2; /* divide by 4 */ 541 for (i = 0; i < max; i++) 542 M_32_SWAP(((int *)p)[i]); 543 } else { 544 M_16_SWAP(bp[0]); 545 max = bp[0] + 2; 546 for (i = 1; i <= max; i++) 547 M_16_SWAP(bp[i]); 548 } 549 } 550 return (0); 551} 552 553/* 554 * Write page p to disk 555 * 556 * Returns: 557 * 0 ==> OK 558 * -1 ==>failure 559 */ 560int 561__put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap) 562{ 563 int fd, page, size; 564 int wsize; 565 566 size = hashp->BSIZE; 567 if ((hashp->fp == -1) && open_temp(hashp)) 568 return (-1); 569 fd = hashp->fp; 570 571 if (hashp->LORDER != BYTE_ORDER) { 572 int i; 573 int max; 574 575 if (is_bitmap) { 576 max = hashp->BSIZE >> 2; /* divide by 4 */ 577 for (i = 0; i < max; i++) 578 M_32_SWAP(((int *)p)[i]); 579 } else { 580 max = ((u_int16_t *)p)[0] + 2; 581 for (i = 0; i <= max; i++) 582 M_16_SWAP(((u_int16_t *)p)[i]); 583 } 584 } 585 if (is_bucket) 586 page = BUCKET_TO_PAGE(bucket); 587 else 588 page = OADDR_TO_PAGE(bucket); 589 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 590 /* Errno is set */ 591 return (-1); 592 if (wsize != size) { 593 errno = EFTYPE; 594 return (-1); 595 } 596 return (0); 597} 598 599#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 600/* 601 * Initialize a new bitmap page. Bitmap pages are left in memory 602 * once they are read in. 603 */ 604int 605__ibitmap(HTAB *hashp, int pnum, int nbits, int ndx) 606{ 607 u_int32_t *ip; 608 int clearbytes, clearints; 609 610 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 611 return (1); 612 hashp->nmaps++; 613 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 614 clearbytes = clearints << INT_TO_BYTE; 615 (void)memset((char *)ip, 0, clearbytes); 616 (void)memset(((char *)ip) + clearbytes, 0xFF, 617 hashp->BSIZE - clearbytes); 618 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 619 SETBIT(ip, 0); 620 hashp->BITMAPS[ndx] = (u_int16_t)pnum; 621 hashp->mapp[ndx] = ip; 622 return (0); 623} 624 625static u_int32_t 626first_free(u_int32_t map) 627{ 628 u_int32_t i, mask; 629 630 mask = 0x1; 631 for (i = 0; i < BITS_PER_MAP; i++) { 632 if (!(mask & map)) 633 return (i); 634 mask = mask << 1; 635 } 636 return (i); 637} 638 639static u_int16_t 640overflow_page(HTAB *hashp) 641{ 642 u_int32_t *freep; 643 int max_free, offset, splitnum; 644 u_int16_t 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_int32_t *)hashp->mapp[i]) && 659 !(freep = fetch_bitmap(hashp, i))) 660 return (0); 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 errno = EFBIG; 691 return (0); 692 } 693 hashp->OVFL_POINT = splitnum; 694 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 695 hashp->SPARES[splitnum-1]--; 696 offset = 1; 697 } 698 699 /* Check if we need to allocate a new bitmap page */ 700 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 701 free_page++; 702 if (free_page >= NCACHED) { 703 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 704 errno = EFBIG; 705 return (0); 706 } 707 /* 708 * This is tricky. The 1 indicates that you want the new page 709 * allocated with 1 clear bit. Actually, you are going to 710 * allocate 2 pages from this map. The first is going to be 711 * the map page, the second is the overflow page we were 712 * looking for. The init_bitmap routine automatically, sets 713 * the first bit of itself to indicate that the bitmap itself 714 * is in use. We would explicitly set the second bit, but 715 * don't have to if we tell init_bitmap not to leave it clear 716 * in the first place. 717 */ 718 if (__ibitmap(hashp, 719 (int)OADDR_OF(splitnum, offset), 1, free_page)) 720 return (0); 721 hashp->SPARES[splitnum]++; 722#ifdef DEBUG2 723 free_bit = 2; 724#endif 725 offset++; 726 if (offset > SPLITMASK) { 727 if (++splitnum >= NCACHED) { 728 (void)_write(STDERR_FILENO, OVMSG, 729 sizeof(OVMSG) - 1); 730 errno = EFBIG; 731 return (0); 732 } 733 hashp->OVFL_POINT = splitnum; 734 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 735 hashp->SPARES[splitnum-1]--; 736 offset = 0; 737 } 738 } else { 739 /* 740 * Free_bit addresses the last used bit. Bump it to address 741 * the first available bit. 742 */ 743 free_bit++; 744 SETBIT(freep, free_bit); 745 } 746 747 /* Calculate address of the new overflow page */ 748 addr = OADDR_OF(splitnum, offset); 749#ifdef DEBUG2 750 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 751 addr, free_bit, free_page); 752#endif 753 return (addr); 754 755found: 756 bit = bit + first_free(freep[j]); 757 SETBIT(freep, bit); 758#ifdef DEBUG2 759 tmp1 = bit; 760 tmp2 = i; 761#endif 762 /* 763 * Bits are addressed starting with 0, but overflow pages are addressed 764 * beginning at 1. Bit is a bit addressnumber, so we need to increment 765 * it to convert it to a page number. 766 */ 767 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 768 if (bit >= hashp->LAST_FREED) 769 hashp->LAST_FREED = bit - 1; 770 771 /* Calculate the split number for this page */ 772 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 773 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 774 if (offset >= SPLITMASK) { 775 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 776 errno = EFBIG; 777 return (0); /* Out of overflow pages */ 778 } 779 addr = OADDR_OF(i, offset); 780#ifdef DEBUG2 781 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 782 addr, tmp1, tmp2); 783#endif 784 785 /* Allocate and return the overflow page */ 786 return (addr); 787} 788 789/* 790 * Mark this overflow page as free. 791 */ 792void 793__free_ovflpage(HTAB *hashp, BUFHEAD *obufp) 794{ 795 u_int16_t addr; 796 u_int32_t *freep; 797 int bit_address, free_page, free_bit; 798 u_int16_t ndx; 799 800 addr = obufp->addr; 801#ifdef DEBUG1 802 (void)fprintf(stderr, "Freeing %d\n", addr); 803#endif 804 ndx = (((u_int16_t)addr) >> SPLITSHIFT); 805 bit_address = 806 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 807 if (bit_address < hashp->LAST_FREED) 808 hashp->LAST_FREED = bit_address; 809 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 810 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 811 812 if (!(freep = hashp->mapp[free_page])) 813 freep = fetch_bitmap(hashp, free_page); 814#ifdef DEBUG 815 /* 816 * This had better never happen. It means we tried to read a bitmap 817 * that has already had overflow pages allocated off it, and we 818 * failed to read it from the file. 819 */ 820 if (!freep) 821 assert(0); 822#endif 823 CLRBIT(freep, free_bit); 824#ifdef DEBUG2 825 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 826 obufp->addr, free_bit, free_page); 827#endif 828 __reclaim_buf(hashp, obufp); 829} 830 831/* 832 * Returns: 833 * 0 success 834 * -1 failure 835 */ 836static int 837open_temp(HTAB *hashp) 838{ 839 sigset_t set, oset; 840 int len; 841 char *envtmp = NULL; 842 char path[MAXPATHLEN]; 843 844 if (issetugid() == 0) 845 envtmp = getenv("TMPDIR"); 846 len = snprintf(path, 847 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp"); 848 if (len < 0 || len >= sizeof(path)) { 849 errno = ENAMETOOLONG; 850 return (-1); 851 } 852 853 /* Block signals; make sure file goes away at process exit. */ 854 (void)sigfillset(&set); 855 (void)_sigprocmask(SIG_BLOCK, &set, &oset); 856 if ((hashp->fp = mkstemp(path)) != -1) { 857 (void)unlink(path); 858 (void)_fcntl(hashp->fp, F_SETFD, 1); 859 } 860 (void)_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 861 return (hashp->fp != -1 ? 0 : -1); 862} 863 864/* 865 * We have to know that the key will fit, but the last entry on the page is 866 * an overflow pair, so we need to shift things. 867 */ 868static void 869squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val) 870{ 871 char *p; 872 u_int16_t free_space, n, off, pageno; 873 874 p = (char *)sp; 875 n = sp[0]; 876 free_space = FREESPACE(sp); 877 off = OFFSET(sp); 878 879 pageno = sp[n - 1]; 880 off -= key->size; 881 sp[n - 1] = off; 882 memmove(p + off, key->data, key->size); 883 off -= val->size; 884 sp[n] = off; 885 memmove(p + off, val->data, val->size); 886 sp[0] = n + 2; 887 sp[n + 1] = pageno; 888 sp[n + 2] = OVFLPAGE; 889 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 890 OFFSET(sp) = off; 891} 892 893static u_int32_t * 894fetch_bitmap(HTAB *hashp, int ndx) 895{ 896 if (ndx >= hashp->nmaps) 897 return (NULL); 898 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 899 return (NULL); 900 if (__get_page(hashp, 901 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 902 free(hashp->mapp[ndx]); 903 return (NULL); 904 } 905 return (hashp->mapp[ndx]); 906} 907 908#ifdef DEBUG4 909int 910print_chain(int addr) 911{ 912 BUFHEAD *bufp; 913 short *bp, oaddr; 914 915 (void)fprintf(stderr, "%d ", addr); 916 bufp = __get_buf(hashp, addr, NULL, 0); 917 bp = (short *)bufp->page; 918 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 919 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 920 oaddr = bp[bp[0] - 1]; 921 (void)fprintf(stderr, "%d ", (int)oaddr); 922 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 923 bp = (short *)bufp->page; 924 } 925 (void)fprintf(stderr, "\n"); 926} 927#endif 928