hash_page.c revision 71579
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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $FreeBSD: head/lib/libc/db/hash/hash_page.c 71579 2001-01-24 13:01:12Z deischen $ 37 */ 38 39#if defined(LIBC_SCCS) && !defined(lint) 40static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94"; 41#endif /* LIBC_SCCS and not lint */ 42 43/* 44 * PACKAGE: hashing 45 * 46 * DESCRIPTION: 47 * Page manipulation for hashing package. 48 * 49 * ROUTINES: 50 * 51 * External 52 * __get_page 53 * __add_ovflpage 54 * Internal 55 * overflow_page 56 * open_temp 57 */ 58 59#include "namespace.h" 60#include <sys/types.h> 61 62#include <errno.h> 63#include <fcntl.h> 64#include <signal.h> 65#include <stdio.h> 66#include <stdlib.h> 67#include <string.h> 68#include <unistd.h> 69#ifdef DEBUG 70#include <assert.h> 71#endif 72#include "un-namespace.h" 73 74#include <db.h> 75#include "hash.h" 76#include "page.h" 77#include "extern.h" 78 79static u_int32_t *fetch_bitmap __P((HTAB *, int)); 80static u_int32_t first_free __P((u_int32_t)); 81static int open_temp __P((HTAB *)); 82static u_int16_t overflow_page __P((HTAB *)); 83static void putpair __P((char *, const DBT *, const DBT *)); 84static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *)); 85static int ugly_split 86 __P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int)); 87 88#define PAGE_INIT(P) { \ 89 ((u_int16_t *)(P))[0] = 0; \ 90 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \ 91 ((u_int16_t *)(P))[2] = hashp->BSIZE; \ 92} 93 94/* 95 * This is called AFTER we have verified that there is room on the page for 96 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 97 * stuff on. 98 */ 99static void 100putpair(p, key, val) 101 char *p; 102 const DBT *key, *val; 103{ 104 register u_int16_t *bp, n, off; 105 106 bp = (u_int16_t *)p; 107 108 /* Enter the key first. */ 109 n = bp[0]; 110 111 off = OFFSET(bp) - key->size; 112 memmove(p + off, key->data, key->size); 113 bp[++n] = off; 114 115 /* Now the data. */ 116 off -= val->size; 117 memmove(p + off, val->data, val->size); 118 bp[++n] = off; 119 120 /* Adjust page info. */ 121 bp[0] = n; 122 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t)); 123 bp[n + 2] = off; 124} 125 126/* 127 * Returns: 128 * 0 OK 129 * -1 error 130 */ 131extern int 132__delpair(hashp, bufp, ndx) 133 HTAB *hashp; 134 BUFHEAD *bufp; 135 register int ndx; 136{ 137 register u_int16_t *bp, newoff; 138 register int n; 139 u_int16_t pairlen; 140 141 bp = (u_int16_t *)bufp->page; 142 n = bp[0]; 143 144 if (bp[ndx + 1] < REAL_KEY) 145 return (__big_delete(hashp, bufp)); 146 if (ndx != 1) 147 newoff = bp[ndx - 1]; 148 else 149 newoff = hashp->BSIZE; 150 pairlen = newoff - bp[ndx + 1]; 151 152 if (ndx != (n - 1)) { 153 /* Hard Case -- need to shuffle keys */ 154 register int i; 155 register char *src = bufp->page + (int)OFFSET(bp); 156 register char *dst = src + (int)pairlen; 157 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 158 159 /* Now adjust the pointers */ 160 for (i = ndx + 2; i <= n; i += 2) { 161 if (bp[i + 1] == OVFLPAGE) { 162 bp[i - 2] = bp[i]; 163 bp[i - 1] = bp[i + 1]; 164 } else { 165 bp[i - 2] = bp[i] + pairlen; 166 bp[i - 1] = bp[i + 1] + pairlen; 167 } 168 } 169 } 170 /* Finally adjust the page data */ 171 bp[n] = OFFSET(bp) + pairlen; 172 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t); 173 bp[0] = n - 2; 174 hashp->NKEYS--; 175 176 bufp->flags |= BUF_MOD; 177 return (0); 178} 179/* 180 * Returns: 181 * 0 ==> OK 182 * -1 ==> Error 183 */ 184extern int 185__split_page(hashp, obucket, nbucket) 186 HTAB *hashp; 187 u_int32_t obucket, nbucket; 188{ 189 register BUFHEAD *new_bufp, *old_bufp; 190 register u_int16_t *ino; 191 register char *np; 192 DBT key, val; 193 int n, ndx, retval; 194 u_int16_t copyto, diff, off, moved; 195 char *op; 196 197 copyto = (u_int16_t)hashp->BSIZE; 198 off = (u_int16_t)hashp->BSIZE; 199 old_bufp = __get_buf(hashp, obucket, NULL, 0); 200 if (old_bufp == NULL) 201 return (-1); 202 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 203 if (new_bufp == NULL) 204 return (-1); 205 206 old_bufp->flags |= (BUF_MOD | BUF_PIN); 207 new_bufp->flags |= (BUF_MOD | BUF_PIN); 208 209 ino = (u_int16_t *)(op = old_bufp->page); 210 np = new_bufp->page; 211 212 moved = 0; 213 214 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 215 if (ino[n + 1] < REAL_KEY) { 216 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 217 (int)copyto, (int)moved); 218 old_bufp->flags &= ~BUF_PIN; 219 new_bufp->flags &= ~BUF_PIN; 220 return (retval); 221 222 } 223 key.data = (u_char *)op + ino[n]; 224 key.size = off - ino[n]; 225 226 if (__call_hash(hashp, key.data, key.size) == obucket) { 227 /* Don't switch page */ 228 diff = copyto - off; 229 if (diff) { 230 copyto = ino[n + 1] + diff; 231 memmove(op + copyto, op + ino[n + 1], 232 off - ino[n + 1]); 233 ino[ndx] = copyto + ino[n] - ino[n + 1]; 234 ino[ndx + 1] = copyto; 235 } else 236 copyto = ino[n + 1]; 237 ndx += 2; 238 } else { 239 /* Switch page */ 240 val.data = (u_char *)op + ino[n + 1]; 241 val.size = ino[n] - ino[n + 1]; 242 putpair(np, &key, &val); 243 moved += 2; 244 } 245 246 off = ino[n + 1]; 247 } 248 249 /* Now clean up the page */ 250 ino[0] -= moved; 251 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3); 252 OFFSET(ino) = copyto; 253 254#ifdef DEBUG3 255 (void)fprintf(stderr, "split %d/%d\n", 256 ((u_int16_t *)np)[0] / 2, 257 ((u_int16_t *)op)[0] / 2); 258#endif 259 /* unpin both pages */ 260 old_bufp->flags &= ~BUF_PIN; 261 new_bufp->flags &= ~BUF_PIN; 262 return (0); 263} 264 265/* 266 * Called when we encounter an overflow or big key/data page during split 267 * handling. This is special cased since we have to begin checking whether 268 * the key/data pairs fit on their respective pages and because we may need 269 * overflow pages for both the old and new pages. 270 * 271 * The first page might be a page with regular key/data pairs in which case 272 * we have a regular overflow condition and just need to go on to the next 273 * page or it might be a big key/data pair in which case we need to fix the 274 * big key/data pair. 275 * 276 * Returns: 277 * 0 ==> success 278 * -1 ==> failure 279 */ 280static int 281ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved) 282 HTAB *hashp; 283 u_int32_t obucket; /* Same as __split_page. */ 284 BUFHEAD *old_bufp, *new_bufp; 285 int copyto; /* First byte on page which contains key/data values. */ 286 int moved; /* Number of pairs moved to new page. */ 287{ 288 register BUFHEAD *bufp; /* Buffer header for ino */ 289 register u_int16_t *ino; /* Page keys come off of */ 290 register u_int16_t *np; /* New page */ 291 register u_int16_t *op; /* Page keys go on to if they aren't moving */ 292 293 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 294 DBT key, val; 295 SPLIT_RETURN ret; 296 u_int16_t n, off, ov_addr, scopyto; 297 char *cino; /* Character value of ino */ 298 299 bufp = old_bufp; 300 ino = (u_int16_t *)old_bufp->page; 301 np = (u_int16_t *)new_bufp->page; 302 op = (u_int16_t *)old_bufp->page; 303 last_bfp = NULL; 304 scopyto = (u_int16_t)copyto; /* ANSI */ 305 306 n = ino[0] - 1; 307 while (n < ino[0]) { 308 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 309 if (__big_split(hashp, old_bufp, 310 new_bufp, bufp, bufp->addr, obucket, &ret)) 311 return (-1); 312 old_bufp = ret.oldp; 313 if (!old_bufp) 314 return (-1); 315 op = (u_int16_t *)old_bufp->page; 316 new_bufp = ret.newp; 317 if (!new_bufp) 318 return (-1); 319 np = (u_int16_t *)new_bufp->page; 320 bufp = ret.nextp; 321 if (!bufp) 322 return (0); 323 cino = (char *)bufp->page; 324 ino = (u_int16_t *)cino; 325 last_bfp = ret.nextp; 326 } else if (ino[n + 1] == OVFLPAGE) { 327 ov_addr = ino[n]; 328 /* 329 * Fix up the old page -- the extra 2 are the fields 330 * which contained the overflow information. 331 */ 332 ino[0] -= (moved + 2); 333 FREESPACE(ino) = 334 scopyto - sizeof(u_int16_t) * (ino[0] + 3); 335 OFFSET(ino) = scopyto; 336 337 bufp = __get_buf(hashp, ov_addr, bufp, 0); 338 if (!bufp) 339 return (-1); 340 341 ino = (u_int16_t *)bufp->page; 342 n = 1; 343 scopyto = hashp->BSIZE; 344 moved = 0; 345 346 if (last_bfp) 347 __free_ovflpage(hashp, last_bfp); 348 last_bfp = bufp; 349 } 350 /* Move regular sized pairs of there are any */ 351 off = hashp->BSIZE; 352 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 353 cino = (char *)ino; 354 key.data = (u_char *)cino + ino[n]; 355 key.size = off - ino[n]; 356 val.data = (u_char *)cino + ino[n + 1]; 357 val.size = ino[n] - ino[n + 1]; 358 off = ino[n + 1]; 359 360 if (__call_hash(hashp, key.data, key.size) == obucket) { 361 /* Keep on old page */ 362 if (PAIRFITS(op, (&key), (&val))) 363 putpair((char *)op, &key, &val); 364 else { 365 old_bufp = 366 __add_ovflpage(hashp, old_bufp); 367 if (!old_bufp) 368 return (-1); 369 op = (u_int16_t *)old_bufp->page; 370 putpair((char *)op, &key, &val); 371 } 372 old_bufp->flags |= BUF_MOD; 373 } else { 374 /* Move to new page */ 375 if (PAIRFITS(np, (&key), (&val))) 376 putpair((char *)np, &key, &val); 377 else { 378 new_bufp = 379 __add_ovflpage(hashp, new_bufp); 380 if (!new_bufp) 381 return (-1); 382 np = (u_int16_t *)new_bufp->page; 383 putpair((char *)np, &key, &val); 384 } 385 new_bufp->flags |= BUF_MOD; 386 } 387 } 388 } 389 if (last_bfp) 390 __free_ovflpage(hashp, last_bfp); 391 return (0); 392} 393 394/* 395 * Add the given pair to the page 396 * 397 * Returns: 398 * 0 ==> OK 399 * 1 ==> failure 400 */ 401extern int 402__addel(hashp, bufp, key, val) 403 HTAB *hashp; 404 BUFHEAD *bufp; 405 const DBT *key, *val; 406{ 407 register u_int16_t *bp, *sop; 408 int do_expand; 409 410 bp = (u_int16_t *)bufp->page; 411 do_expand = 0; 412 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 413 /* Exception case */ 414 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 415 /* This is the last page of a big key/data pair 416 and we need to add another page */ 417 break; 418 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 419 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 420 if (!bufp) 421 return (-1); 422 bp = (u_int16_t *)bufp->page; 423 } else 424 /* Try to squeeze key on this page */ 425 if (FREESPACE(bp) > PAIRSIZE(key, val)) { 426 squeeze_key(bp, key, val); 427 return (0); 428 } else { 429 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 430 if (!bufp) 431 return (-1); 432 bp = (u_int16_t *)bufp->page; 433 } 434 435 if (PAIRFITS(bp, key, val)) 436 putpair(bufp->page, key, val); 437 else { 438 do_expand = 1; 439 bufp = __add_ovflpage(hashp, bufp); 440 if (!bufp) 441 return (-1); 442 sop = (u_int16_t *)bufp->page; 443 444 if (PAIRFITS(sop, key, val)) 445 putpair((char *)sop, key, val); 446 else 447 if (__big_insert(hashp, bufp, key, val)) 448 return (-1); 449 } 450 bufp->flags |= BUF_MOD; 451 /* 452 * If the average number of keys per bucket exceeds the fill factor, 453 * expand the table. 454 */ 455 hashp->NKEYS++; 456 if (do_expand || 457 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 458 return (__expand_table(hashp)); 459 return (0); 460} 461 462/* 463 * 464 * Returns: 465 * pointer on success 466 * NULL on error 467 */ 468extern BUFHEAD * 469__add_ovflpage(hashp, bufp) 470 HTAB *hashp; 471 BUFHEAD *bufp; 472{ 473 register u_int16_t *sp; 474 u_int16_t ndx, ovfl_num; 475#ifdef DEBUG1 476 int tmp1, tmp2; 477#endif 478 sp = (u_int16_t *)bufp->page; 479 480 /* Check if we are dynamically determining the fill factor */ 481 if (hashp->FFACTOR == DEF_FFACTOR) { 482 hashp->FFACTOR = sp[0] >> 1; 483 if (hashp->FFACTOR < MIN_FFACTOR) 484 hashp->FFACTOR = MIN_FFACTOR; 485 } 486 bufp->flags |= BUF_MOD; 487 ovfl_num = overflow_page(hashp); 488#ifdef DEBUG1 489 tmp1 = bufp->addr; 490 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 491#endif 492 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 493 return (NULL); 494 bufp->ovfl->flags |= BUF_MOD; 495#ifdef DEBUG1 496 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 497 tmp1, tmp2, bufp->ovfl->addr); 498#endif 499 ndx = sp[0]; 500 /* 501 * Since a pair is allocated on a page only if there's room to add 502 * an overflow page, we know that the OVFL information will fit on 503 * the page. 504 */ 505 sp[ndx + 4] = OFFSET(sp); 506 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 507 sp[ndx + 1] = ovfl_num; 508 sp[ndx + 2] = OVFLPAGE; 509 sp[0] = ndx + 2; 510#ifdef HASH_STATISTICS 511 hash_overflows++; 512#endif 513 return (bufp->ovfl); 514} 515 516/* 517 * Returns: 518 * 0 indicates SUCCESS 519 * -1 indicates FAILURE 520 */ 521extern int 522__get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap) 523 HTAB *hashp; 524 char *p; 525 u_int32_t bucket; 526 int is_bucket, is_disk, is_bitmap; 527{ 528 register int fd, page, size; 529 int rsize; 530 u_int16_t *bp; 531 532 fd = hashp->fp; 533 size = hashp->BSIZE; 534 535 if ((fd == -1) || !is_disk) { 536 PAGE_INIT(p); 537 return (0); 538 } 539 if (is_bucket) 540 page = BUCKET_TO_PAGE(bucket); 541 else 542 page = OADDR_TO_PAGE(bucket); 543 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 544 ((rsize = _read(fd, p, size)) == -1)) 545 return (-1); 546 bp = (u_int16_t *)p; 547 if (!rsize) 548 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 549 else 550 if (rsize != size) { 551 errno = EFTYPE; 552 return (-1); 553 } 554 if (!is_bitmap && !bp[0]) { 555 PAGE_INIT(p); 556 } else 557 if (hashp->LORDER != BYTE_ORDER) { 558 register int i, max; 559 560 if (is_bitmap) { 561 max = hashp->BSIZE >> 2; /* divide by 4 */ 562 for (i = 0; i < max; i++) 563 M_32_SWAP(((int *)p)[i]); 564 } else { 565 M_16_SWAP(bp[0]); 566 max = bp[0] + 2; 567 for (i = 1; i <= max; i++) 568 M_16_SWAP(bp[i]); 569 } 570 } 571 return (0); 572} 573 574/* 575 * Write page p to disk 576 * 577 * Returns: 578 * 0 ==> OK 579 * -1 ==>failure 580 */ 581extern int 582__put_page(hashp, p, bucket, is_bucket, is_bitmap) 583 HTAB *hashp; 584 char *p; 585 u_int32_t bucket; 586 int is_bucket, is_bitmap; 587{ 588 register int fd, page, size; 589 int wsize; 590 591 size = hashp->BSIZE; 592 if ((hashp->fp == -1) && open_temp(hashp)) 593 return (-1); 594 fd = hashp->fp; 595 596 if (hashp->LORDER != BYTE_ORDER) { 597 register int i; 598 register int max; 599 600 if (is_bitmap) { 601 max = hashp->BSIZE >> 2; /* divide by 4 */ 602 for (i = 0; i < max; i++) 603 M_32_SWAP(((int *)p)[i]); 604 } else { 605 max = ((u_int16_t *)p)[0] + 2; 606 for (i = 0; i <= max; i++) 607 M_16_SWAP(((u_int16_t *)p)[i]); 608 } 609 } 610 if (is_bucket) 611 page = BUCKET_TO_PAGE(bucket); 612 else 613 page = OADDR_TO_PAGE(bucket); 614 if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) || 615 ((wsize = _write(fd, p, size)) == -1)) 616 /* Errno is set */ 617 return (-1); 618 if (wsize != size) { 619 errno = EFTYPE; 620 return (-1); 621 } 622 return (0); 623} 624 625#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 626/* 627 * Initialize a new bitmap page. Bitmap pages are left in memory 628 * once they are read in. 629 */ 630extern int 631__ibitmap(hashp, pnum, nbits, ndx) 632 HTAB *hashp; 633 int pnum, nbits, ndx; 634{ 635 u_int32_t *ip; 636 int clearbytes, clearints; 637 638 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 639 return (1); 640 hashp->nmaps++; 641 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 642 clearbytes = clearints << INT_TO_BYTE; 643 (void)memset((char *)ip, 0, clearbytes); 644 (void)memset(((char *)ip) + clearbytes, 0xFF, 645 hashp->BSIZE - clearbytes); 646 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 647 SETBIT(ip, 0); 648 hashp->BITMAPS[ndx] = (u_int16_t)pnum; 649 hashp->mapp[ndx] = ip; 650 return (0); 651} 652 653static u_int32_t 654first_free(map) 655 u_int32_t map; 656{ 657 register u_int32_t i, mask; 658 659 mask = 0x1; 660 for (i = 0; i < BITS_PER_MAP; i++) { 661 if (!(mask & map)) 662 return (i); 663 mask = mask << 1; 664 } 665 return (i); 666} 667 668static u_int16_t 669overflow_page(hashp) 670 HTAB *hashp; 671{ 672 register u_int32_t *freep; 673 register int max_free, offset, splitnum; 674 u_int16_t addr; 675 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 676#ifdef DEBUG2 677 int tmp1, tmp2; 678#endif 679 splitnum = hashp->OVFL_POINT; 680 max_free = hashp->SPARES[splitnum]; 681 682 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 683 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 684 685 /* Look through all the free maps to find the first free block */ 686 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 687 for ( i = first_page; i <= free_page; i++ ) { 688 if (!(freep = (u_int32_t *)hashp->mapp[i]) && 689 !(freep = fetch_bitmap(hashp, i))) 690 return (0); 691 if (i == free_page) 692 in_use_bits = free_bit; 693 else 694 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 695 696 if (i == first_page) { 697 bit = hashp->LAST_FREED & 698 ((hashp->BSIZE << BYTE_SHIFT) - 1); 699 j = bit / BITS_PER_MAP; 700 bit = bit & ~(BITS_PER_MAP - 1); 701 } else { 702 bit = 0; 703 j = 0; 704 } 705 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 706 if (freep[j] != ALL_SET) 707 goto found; 708 } 709 710 /* No Free Page Found */ 711 hashp->LAST_FREED = hashp->SPARES[splitnum]; 712 hashp->SPARES[splitnum]++; 713 offset = hashp->SPARES[splitnum] - 714 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 715 716#define OVMSG "HASH: Out of overflow pages. Increase page size\n" 717 if (offset > SPLITMASK) { 718 if (++splitnum >= NCACHED) { 719 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 720 return (0); 721 } 722 hashp->OVFL_POINT = splitnum; 723 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 724 hashp->SPARES[splitnum-1]--; 725 offset = 1; 726 } 727 728 /* Check if we need to allocate a new bitmap page */ 729 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 730 free_page++; 731 if (free_page >= NCACHED) { 732 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 733 return (0); 734 } 735 /* 736 * This is tricky. The 1 indicates that you want the new page 737 * allocated with 1 clear bit. Actually, you are going to 738 * allocate 2 pages from this map. The first is going to be 739 * the map page, the second is the overflow page we were 740 * looking for. The init_bitmap routine automatically, sets 741 * the first bit of itself to indicate that the bitmap itself 742 * is in use. We would explicitly set the second bit, but 743 * don't have to if we tell init_bitmap not to leave it clear 744 * in the first place. 745 */ 746 if (__ibitmap(hashp, 747 (int)OADDR_OF(splitnum, offset), 1, free_page)) 748 return (0); 749 hashp->SPARES[splitnum]++; 750#ifdef DEBUG2 751 free_bit = 2; 752#endif 753 offset++; 754 if (offset > SPLITMASK) { 755 if (++splitnum >= NCACHED) { 756 (void)_write(STDERR_FILENO, OVMSG, 757 sizeof(OVMSG) - 1); 758 return (0); 759 } 760 hashp->OVFL_POINT = splitnum; 761 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 762 hashp->SPARES[splitnum-1]--; 763 offset = 0; 764 } 765 } else { 766 /* 767 * Free_bit addresses the last used bit. Bump it to address 768 * the first available bit. 769 */ 770 free_bit++; 771 SETBIT(freep, free_bit); 772 } 773 774 /* Calculate address of the new overflow page */ 775 addr = OADDR_OF(splitnum, offset); 776#ifdef DEBUG2 777 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 778 addr, free_bit, free_page); 779#endif 780 return (addr); 781 782found: 783 bit = bit + first_free(freep[j]); 784 SETBIT(freep, bit); 785#ifdef DEBUG2 786 tmp1 = bit; 787 tmp2 = i; 788#endif 789 /* 790 * Bits are addressed starting with 0, but overflow pages are addressed 791 * beginning at 1. Bit is a bit addressnumber, so we need to increment 792 * it to convert it to a page number. 793 */ 794 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 795 if (bit >= hashp->LAST_FREED) 796 hashp->LAST_FREED = bit - 1; 797 798 /* Calculate the split number for this page */ 799 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 800 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 801 if (offset >= SPLITMASK) 802 return (0); /* Out of overflow pages */ 803 addr = OADDR_OF(i, offset); 804#ifdef DEBUG2 805 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 806 addr, tmp1, tmp2); 807#endif 808 809 /* Allocate and return the overflow page */ 810 return (addr); 811} 812 813/* 814 * Mark this overflow page as free. 815 */ 816extern void 817__free_ovflpage(hashp, obufp) 818 HTAB *hashp; 819 BUFHEAD *obufp; 820{ 821 register u_int16_t addr; 822 u_int32_t *freep; 823 int bit_address, free_page, free_bit; 824 u_int16_t ndx; 825 826 addr = obufp->addr; 827#ifdef DEBUG1 828 (void)fprintf(stderr, "Freeing %d\n", addr); 829#endif 830 ndx = (((u_int16_t)addr) >> SPLITSHIFT); 831 bit_address = 832 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 833 if (bit_address < hashp->LAST_FREED) 834 hashp->LAST_FREED = bit_address; 835 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 836 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 837 838 if (!(freep = hashp->mapp[free_page])) 839 freep = fetch_bitmap(hashp, free_page); 840#ifdef DEBUG 841 /* 842 * This had better never happen. It means we tried to read a bitmap 843 * that has already had overflow pages allocated off it, and we 844 * failed to read it from the file. 845 */ 846 if (!freep) 847 assert(0); 848#endif 849 CLRBIT(freep, free_bit); 850#ifdef DEBUG2 851 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 852 obufp->addr, free_bit, free_page); 853#endif 854 __reclaim_buf(hashp, obufp); 855} 856 857/* 858 * Returns: 859 * 0 success 860 * -1 failure 861 */ 862static int 863open_temp(hashp) 864 HTAB *hashp; 865{ 866 sigset_t set, oset; 867 static char namestr[] = "_hashXXXXXX"; 868 869 /* Block signals; make sure file goes away at process exit. */ 870 (void)sigfillset(&set); 871 (void)_sigprocmask(SIG_BLOCK, &set, &oset); 872 if ((hashp->fp = mkstemp(namestr)) != -1) { 873 (void)unlink(namestr); 874 (void)_fcntl(hashp->fp, F_SETFD, 1); 875 } 876 (void)_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 877 return (hashp->fp != -1 ? 0 : -1); 878} 879 880/* 881 * We have to know that the key will fit, but the last entry on the page is 882 * an overflow pair, so we need to shift things. 883 */ 884static void 885squeeze_key(sp, key, val) 886 u_int16_t *sp; 887 const DBT *key, *val; 888{ 889 register char *p; 890 u_int16_t free_space, n, off, pageno; 891 892 p = (char *)sp; 893 n = sp[0]; 894 free_space = FREESPACE(sp); 895 off = OFFSET(sp); 896 897 pageno = sp[n - 1]; 898 off -= key->size; 899 sp[n - 1] = off; 900 memmove(p + off, key->data, key->size); 901 off -= val->size; 902 sp[n] = off; 903 memmove(p + off, val->data, val->size); 904 sp[0] = n + 2; 905 sp[n + 1] = pageno; 906 sp[n + 2] = OVFLPAGE; 907 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 908 OFFSET(sp) = off; 909} 910 911static u_int32_t * 912fetch_bitmap(hashp, ndx) 913 HTAB *hashp; 914 int ndx; 915{ 916 if (ndx >= hashp->nmaps) 917 return (NULL); 918 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 919 return (NULL); 920 if (__get_page(hashp, 921 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 922 free(hashp->mapp[ndx]); 923 return (NULL); 924 } 925 return (hashp->mapp[ndx]); 926} 927 928#ifdef DEBUG4 929int 930print_chain(addr) 931 int addr; 932{ 933 BUFHEAD *bufp; 934 short *bp, oaddr; 935 936 (void)fprintf(stderr, "%d ", addr); 937 bufp = __get_buf(hashp, addr, NULL, 0); 938 bp = (short *)bufp->page; 939 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 940 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 941 oaddr = bp[bp[0] - 1]; 942 (void)fprintf(stderr, "%d ", (int)oaddr); 943 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 944 bp = (short *)bufp->page; 945 } 946 (void)fprintf(stderr, "\n"); 947} 948#endif 949