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