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 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)hash_bigkey.c 8.3 (Berkeley) 5/31/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 /* 44 * PACKAGE: hash 45 * DESCRIPTION: 46 * Big key/data handling for the hashing package. 47 * 48 * ROUTINES: 49 * External 50 * __big_keydata 51 * __big_split 52 * __big_insert 53 * __big_return 54 * __big_delete 55 * __find_last_page 56 * Internal 57 * collect_key 58 * collect_data 59 */ 60 61 #include <sys/param.h> 62 63 #include <errno.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 68 #ifdef DEBUG 69 #include <assert.h> 70 #endif 71 72 #include <db.h> 73 #include "hash.h" 74 #include "page.h" 75 #include "extern.h" 76 77 static int collect_key(HTAB *, BUFHEAD *, int, DBT *, int); 78 static int collect_data(HTAB *, BUFHEAD *, int, int); 79 80 /* 81 * Big_insert 82 * 83 * You need to do an insert and the key/data pair is too big 84 * 85 * Returns: 86 * 0 ==> OK 87 *-1 ==> ERROR 88 */ 89 extern int 90 __big_insert(hashp, bufp, key, val) 91 HTAB *hashp; 92 BUFHEAD *bufp; 93 const DBT *key, *val; 94 { 95 u_int16_t *p; 96 int key_size, n, val_size; 97 u_int16_t space, move_bytes, off; 98 char *cp, *key_data, *val_data; 99 100 cp = bufp->page; /* Character pointer of p. */ 101 p = (u_int16_t *)cp; 102 103 key_data = (char *)key->data; 104 key_size = key->size; 105 val_data = (char *)val->data; 106 val_size = val->size; 107 108 /* First move the Key */ 109 for (space = FREESPACE(p) - BIGOVERHEAD; key_size; 110 space = FREESPACE(p) - BIGOVERHEAD) { 111 move_bytes = MIN(space, key_size); 112 off = OFFSET(p) - move_bytes; 113 memmove(cp + off, key_data, move_bytes); 114 key_size -= move_bytes; 115 key_data += move_bytes; 116 n = p[0]; 117 p[++n] = off; 118 p[0] = ++n; 119 FREESPACE(p) = off - PAGE_META(n); 120 OFFSET(p) = off; 121 p[n] = PARTIAL_KEY; 122 bufp = __add_ovflpage(hashp, bufp); 123 if (!bufp) 124 return (-1); 125 n = p[0]; 126 if (!key_size) { 127 if (FREESPACE(p)) { 128 move_bytes = MIN(FREESPACE(p), val_size); 129 off = OFFSET(p) - move_bytes; 130 p[n] = off; 131 memmove(cp + off, val_data, move_bytes); 132 val_data += move_bytes; 133 val_size -= move_bytes; 134 p[n - 2] = FULL_KEY_DATA; 135 FREESPACE(p) = FREESPACE(p) - move_bytes; 136 OFFSET(p) = off; 137 } else 138 p[n - 2] = FULL_KEY; 139 } 140 p = (u_int16_t *)bufp->page; 141 cp = bufp->page; 142 bufp->flags |= BUF_MOD; 143 } 144 145 /* Now move the data */ 146 for (space = FREESPACE(p) - BIGOVERHEAD; val_size; 147 space = FREESPACE(p) - BIGOVERHEAD) { 148 move_bytes = MIN(space, val_size); 149 /* 150 * Here's the hack to make sure that if the data ends on the 151 * same page as the key ends, FREESPACE is at least one. 152 */ 153 if (space == val_size && val_size == val->size) 154 move_bytes--; 155 off = OFFSET(p) - move_bytes; 156 memmove(cp + off, val_data, move_bytes); 157 val_size -= move_bytes; 158 val_data += move_bytes; 159 n = p[0]; 160 p[++n] = off; 161 p[0] = ++n; 162 FREESPACE(p) = off - PAGE_META(n); 163 OFFSET(p) = off; 164 if (val_size) { 165 p[n] = FULL_KEY; 166 bufp = __add_ovflpage(hashp, bufp); 167 if (!bufp) 168 return (-1); 169 cp = bufp->page; 170 p = (u_int16_t *)cp; 171 } else 172 p[n] = FULL_KEY_DATA; 173 bufp->flags |= BUF_MOD; 174 } 175 return (0); 176 } 177 178 /* 179 * Called when bufp's page contains a partial key (index should be 1) 180 * 181 * All pages in the big key/data pair except bufp are freed. We cannot 182 * free bufp because the page pointing to it is lost and we can't get rid 183 * of its pointer. 184 * 185 * Returns: 186 * 0 => OK 187 *-1 => ERROR 188 */ 189 extern int 190 __big_delete(hashp, bufp) 191 HTAB *hashp; 192 BUFHEAD *bufp; 193 { 194 BUFHEAD *last_bfp, *rbufp; 195 u_int16_t *bp, pageno; 196 int key_done, n; 197 198 rbufp = bufp; 199 last_bfp = NULL; 200 bp = (u_int16_t *)bufp->page; 201 pageno = 0; 202 key_done = 0; 203 204 while (!key_done || (bp[2] != FULL_KEY_DATA)) { 205 if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA) 206 key_done = 1; 207 208 /* 209 * If there is freespace left on a FULL_KEY_DATA page, then 210 * the data is short and fits entirely on this page, and this 211 * is the last page. 212 */ 213 if (bp[2] == FULL_KEY_DATA && FREESPACE(bp)) 214 break; 215 pageno = bp[bp[0] - 1]; 216 rbufp->flags |= BUF_MOD; 217 rbufp = __get_buf(hashp, pageno, rbufp, 0); 218 if (last_bfp) 219 __free_ovflpage(hashp, last_bfp); 220 last_bfp = rbufp; 221 if (!rbufp) 222 return (-1); /* Error. */ 223 bp = (u_int16_t *)rbufp->page; 224 } 225 226 /* 227 * If we get here then rbufp points to the last page of the big 228 * key/data pair. Bufp points to the first one -- it should now be 229 * empty pointing to the next page after this pair. Can't free it 230 * because we don't have the page pointing to it. 231 */ 232 233 /* This is information from the last page of the pair. */ 234 n = bp[0]; 235 pageno = bp[n - 1]; 236 237 /* Now, bp is the first page of the pair. */ 238 bp = (u_int16_t *)bufp->page; 239 if (n > 2) { 240 /* There is an overflow page. */ 241 bp[1] = pageno; 242 bp[2] = OVFLPAGE; 243 bufp->ovfl = rbufp->ovfl; 244 } else 245 /* This is the last page. */ 246 bufp->ovfl = NULL; 247 n -= 2; 248 bp[0] = n; 249 FREESPACE(bp) = hashp->BSIZE - PAGE_META(n); 250 OFFSET(bp) = hashp->BSIZE - 1; 251 252 bufp->flags |= BUF_MOD; 253 if (rbufp) 254 __free_ovflpage(hashp, rbufp); 255 if (last_bfp != rbufp) 256 __free_ovflpage(hashp, last_bfp); 257 258 hashp->NKEYS--; 259 return (0); 260 } 261 /* 262 * Returns: 263 * 0 = key not found 264 * -1 = get next overflow page 265 * -2 means key not found and this is big key/data 266 * -3 error 267 */ 268 extern int 269 __find_bigpair(hashp, bufp, ndx, key, size) 270 HTAB *hashp; 271 BUFHEAD *bufp; 272 int ndx; 273 char *key; 274 int size; 275 { 276 u_int16_t *bp; 277 char *p; 278 int ksize; 279 u_int16_t bytes; 280 char *kkey; 281 282 bp = (u_int16_t *)bufp->page; 283 p = bufp->page; 284 ksize = size; 285 kkey = key; 286 287 for (bytes = hashp->BSIZE - bp[ndx]; 288 bytes <= size && bp[ndx + 1] == PARTIAL_KEY; 289 bytes = hashp->BSIZE - bp[ndx]) { 290 if (memcmp(p + bp[ndx], kkey, bytes)) 291 return (-2); 292 kkey += bytes; 293 ksize -= bytes; 294 bufp = __get_buf(hashp, bp[ndx + 2], bufp, 0); 295 if (!bufp) 296 return (-3); 297 p = bufp->page; 298 bp = (u_int16_t *)p; 299 ndx = 1; 300 } 301 302 if (bytes != ksize || memcmp(p + bp[ndx], kkey, bytes)) { 303 #ifdef HASH_STATISTICS 304 ++hash_collisions; 305 #endif 306 return (-2); 307 } else 308 return (ndx); 309 } 310 311 /* 312 * Given the buffer pointer of the first overflow page of a big pair, 313 * find the end of the big pair 314 * 315 * This will set bpp to the buffer header of the last page of the big pair. 316 * It will return the pageno of the overflow page following the last page 317 * of the pair; 0 if there isn't any (i.e. big pair is the last key in the 318 * bucket) 319 */ 320 extern u_int16_t 321 __find_last_page(hashp, bpp) 322 HTAB *hashp; 323 BUFHEAD **bpp; 324 { 325 BUFHEAD *bufp; 326 u_int16_t *bp, pageno; 327 int n; 328 329 bufp = *bpp; 330 bp = (u_int16_t *)bufp->page; 331 for (;;) { 332 n = bp[0]; 333 334 /* 335 * This is the last page if: the tag is FULL_KEY_DATA and 336 * either only 2 entries OVFLPAGE marker is explicit there 337 * is freespace on the page. 338 */ 339 if (bp[2] == FULL_KEY_DATA && 340 ((n == 2) || (bp[n] == OVFLPAGE) || (FREESPACE(bp)))) 341 break; 342 343 pageno = bp[n - 1]; 344 bufp = __get_buf(hashp, pageno, bufp, 0); 345 if (!bufp) 346 return (0); /* Need to indicate an error! */ 347 bp = (u_int16_t *)bufp->page; 348 } 349 350 *bpp = bufp; 351 if (bp[0] > 2) 352 return (bp[3]); 353 else 354 return (0); 355 } 356 357 /* 358 * Return the data for the key/data pair that begins on this page at this 359 * index (index should always be 1). 360 */ 361 extern int 362 __big_return(hashp, bufp, ndx, val, set_current) 363 HTAB *hashp; 364 BUFHEAD *bufp; 365 int ndx; 366 DBT *val; 367 int set_current; 368 { 369 BUFHEAD *save_p; 370 u_int16_t *bp, len, off, save_addr; 371 char *tp; 372 373 bp = (u_int16_t *)bufp->page; 374 while (bp[ndx + 1] == PARTIAL_KEY) { 375 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 376 if (!bufp) 377 return (-1); 378 bp = (u_int16_t *)bufp->page; 379 ndx = 1; 380 } 381 382 if (bp[ndx + 1] == FULL_KEY) { 383 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 384 if (!bufp) 385 return (-1); 386 bp = (u_int16_t *)bufp->page; 387 save_p = bufp; 388 save_addr = save_p->addr; 389 off = bp[1]; 390 len = 0; 391 } else 392 if (!FREESPACE(bp)) { 393 /* 394 * This is a hack. We can't distinguish between 395 * FULL_KEY_DATA that contains complete data or 396 * incomplete data, so we require that if the data 397 * is complete, there is at least 1 byte of free 398 * space left. 399 */ 400 off = bp[bp[0]]; 401 len = bp[1] - off; 402 save_p = bufp; 403 save_addr = bufp->addr; 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 /* The data is all on one page. */ 410 tp = (char *)bp; 411 off = bp[bp[0]]; 412 val->data = (u_char *)tp + off; 413 val->size = bp[1] - off; 414 if (set_current) { 415 if (bp[0] == 2) { /* No more buckets in 416 * chain */ 417 hashp->cpage = NULL; 418 hashp->cbucket++; 419 hashp->cndx = 1; 420 } else { 421 hashp->cpage = __get_buf(hashp, 422 bp[bp[0] - 1], bufp, 0); 423 if (!hashp->cpage) 424 return (-1); 425 hashp->cndx = 1; 426 if (!((u_int16_t *) 427 hashp->cpage->page)[0]) { 428 hashp->cbucket++; 429 hashp->cpage = NULL; 430 } 431 } 432 } 433 return (0); 434 } 435 436 val->size = collect_data(hashp, bufp, (int)len, set_current); 437 if (val->size == -1) 438 return (-1); 439 if (save_p->addr != save_addr) { 440 /* We are pretty short on buffers. */ 441 errno = EINVAL; /* OUT OF BUFFERS */ 442 return (-1); 443 } 444 memmove(hashp->tmp_buf, (save_p->page) + off, len); 445 val->data = (u_char *)hashp->tmp_buf; 446 return (0); 447 } 448 /* 449 * Count how big the total datasize is by recursing through the pages. Then 450 * allocate a buffer and copy the data as you recurse up. 451 */ 452 static int 453 collect_data(hashp, bufp, len, set) 454 HTAB *hashp; 455 BUFHEAD *bufp; 456 int len, set; 457 { 458 u_int16_t *bp; 459 char *p; 460 BUFHEAD *xbp; 461 u_int16_t save_addr; 462 int mylen, totlen; 463 464 p = bufp->page; 465 bp = (u_int16_t *)p; 466 mylen = hashp->BSIZE - bp[1]; 467 save_addr = bufp->addr; 468 469 if (bp[2] == FULL_KEY_DATA) { /* End of Data */ 470 totlen = len + mylen; 471 if (hashp->tmp_buf) 472 free(hashp->tmp_buf); 473 if ((hashp->tmp_buf = (char *)malloc(totlen)) == NULL) 474 return (-1); 475 if (set) { 476 hashp->cndx = 1; 477 if (bp[0] == 2) { /* No more buckets in chain */ 478 hashp->cpage = NULL; 479 hashp->cbucket++; 480 } else { 481 hashp->cpage = 482 __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 483 if (!hashp->cpage) 484 return (-1); 485 else if (!((u_int16_t *)hashp->cpage->page)[0]) { 486 hashp->cbucket++; 487 hashp->cpage = NULL; 488 } 489 } 490 } 491 } else { 492 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 493 if (!xbp || ((totlen = 494 collect_data(hashp, xbp, len + mylen, set)) < 1)) 495 return (-1); 496 } 497 if (bufp->addr != save_addr) { 498 errno = EINVAL; /* Out of buffers. */ 499 return (-1); 500 } 501 memmove(&hashp->tmp_buf[len], (bufp->page) + bp[1], mylen); 502 return (totlen); 503 } 504 505 /* 506 * Fill in the key and data for this big pair. 507 */ 508 extern int 509 __big_keydata(hashp, bufp, key, val, set) 510 HTAB *hashp; 511 BUFHEAD *bufp; 512 DBT *key, *val; 513 int set; 514 { 515 key->size = collect_key(hashp, bufp, 0, val, set); 516 if (key->size == -1) 517 return (-1); 518 key->data = (u_char *)hashp->tmp_key; 519 return (0); 520 } 521 522 /* 523 * Count how big the total key size is by recursing through the pages. Then 524 * collect the data, allocate a buffer and copy the key as you recurse up. 525 */ 526 static int 527 collect_key(hashp, bufp, len, val, set) 528 HTAB *hashp; 529 BUFHEAD *bufp; 530 int len; 531 DBT *val; 532 int set; 533 { 534 BUFHEAD *xbp; 535 char *p; 536 int mylen, totlen; 537 u_int16_t *bp, save_addr; 538 539 p = bufp->page; 540 bp = (u_int16_t *)p; 541 mylen = hashp->BSIZE - bp[1]; 542 543 save_addr = bufp->addr; 544 totlen = len + mylen; 545 if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA) { /* End of Key. */ 546 if (hashp->tmp_key != NULL) 547 free(hashp->tmp_key); 548 if ((hashp->tmp_key = (char *)malloc(totlen)) == NULL) 549 return (-1); 550 if (__big_return(hashp, bufp, 1, val, set)) 551 return (-1); 552 } else { 553 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 554 if (!xbp || ((totlen = 555 collect_key(hashp, xbp, totlen, val, set)) < 1)) 556 return (-1); 557 } 558 if (bufp->addr != save_addr) { 559 errno = EINVAL; /* MIS -- OUT OF BUFFERS */ 560 return (-1); 561 } 562 memmove(&hashp->tmp_key[len], (bufp->page) + bp[1], mylen); 563 return (totlen); 564 } 565 566 /* 567 * Returns: 568 * 0 => OK 569 * -1 => error 570 */ 571 extern int 572 __big_split(hashp, op, np, big_keyp, addr, obucket, ret) 573 HTAB *hashp; 574 BUFHEAD *op; /* Pointer to where to put keys that go in old bucket */ 575 BUFHEAD *np; /* Pointer to new bucket page */ 576 /* Pointer to first page containing the big key/data */ 577 BUFHEAD *big_keyp; 578 int addr; /* Address of big_keyp */ 579 u_int32_t obucket;/* Old Bucket */ 580 SPLIT_RETURN *ret; 581 { 582 BUFHEAD *tmpp; 583 u_int16_t *tp; 584 BUFHEAD *bp; 585 DBT key, val; 586 u_int32_t change; 587 u_int16_t free_space, n, off; 588 589 bp = big_keyp; 590 591 /* Now figure out where the big key/data goes */ 592 if (__big_keydata(hashp, big_keyp, &key, &val, 0)) 593 return (-1); 594 change = (__call_hash(hashp, key.data, key.size) != obucket); 595 596 if ( (ret->next_addr = __find_last_page(hashp, &big_keyp)) ) { 597 if (!(ret->nextp = 598 __get_buf(hashp, ret->next_addr, big_keyp, 0))) 599 return (-1);; 600 } else 601 ret->nextp = NULL; 602 603 /* Now make one of np/op point to the big key/data pair */ 604 #ifdef DEBUG 605 assert(np->ovfl == NULL); 606 #endif 607 if (change) 608 tmpp = np; 609 else 610 tmpp = op; 611 612 tmpp->flags |= BUF_MOD; 613 #ifdef DEBUG1 614 (void)fprintf(stderr, 615 "BIG_SPLIT: %d->ovfl was %d is now %d\n", tmpp->addr, 616 (tmpp->ovfl ? tmpp->ovfl->addr : 0), (bp ? bp->addr : 0)); 617 #endif 618 tmpp->ovfl = bp; /* one of op/np point to big_keyp */ 619 tp = (u_int16_t *)tmpp->page; 620 #ifdef DEBUG 621 assert(FREESPACE(tp) >= OVFLSIZE); 622 #endif 623 n = tp[0]; 624 off = OFFSET(tp); 625 free_space = FREESPACE(tp); 626 tp[++n] = (u_int16_t)addr; 627 tp[++n] = OVFLPAGE; 628 tp[0] = n; 629 OFFSET(tp) = off; 630 FREESPACE(tp) = free_space - OVFLSIZE; 631 632 /* 633 * Finally, set the new and old return values. BIG_KEYP contains a 634 * pointer to the last page of the big key_data pair. Make sure that 635 * big_keyp has no following page (2 elements) or create an empty 636 * following page. 637 */ 638 639 ret->newp = np; 640 ret->oldp = op; 641 642 tp = (u_int16_t *)big_keyp->page; 643 big_keyp->flags |= BUF_MOD; 644 if (tp[0] > 2) { 645 /* 646 * There may be either one or two offsets on this page. If 647 * there is one, then the overflow page is linked on normally 648 * and tp[4] is OVFLPAGE. If there are two, tp[4] contains 649 * the second offset and needs to get stuffed in after the 650 * next overflow page is added. 651 */ 652 n = tp[4]; 653 free_space = FREESPACE(tp); 654 off = OFFSET(tp); 655 tp[0] -= 2; 656 FREESPACE(tp) = free_space + OVFLSIZE; 657 OFFSET(tp) = off; 658 tmpp = __add_ovflpage(hashp, big_keyp); 659 if (!tmpp) 660 return (-1); 661 tp[4] = n; 662 } else 663 tmpp = big_keyp; 664 665 if (change) 666 ret->newp = tmpp; 667 else 668 ret->oldp = tmpp; 669 return (0); 670 } 671