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 * Mike Olson. 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[] = "@(#)bt_split.c 8.10 (Berkeley) 1/9/95"; 35#endif /* LIBC_SCCS and not lint */ 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD$"); 38 39#include <sys/param.h> 40 41#include <limits.h> 42#include <stdio.h> 43#include <stdlib.h> 44#include <string.h> 45 46#include <db.h> 47#include "btree.h" 48 49static int bt_broot(BTREE *, PAGE *, PAGE *, PAGE *); 50static PAGE *bt_page(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 51static int bt_preserve(BTREE *, pgno_t); 52static PAGE *bt_psplit(BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t); 53static PAGE *bt_root(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 54static int bt_rroot(BTREE *, PAGE *, PAGE *, PAGE *); 55static recno_t rec_total(PAGE *); 56 57#ifdef STATISTICS 58u_long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 59#endif 60 61/* 62 * __BT_SPLIT -- Split the tree. 63 * 64 * Parameters: 65 * t: tree 66 * sp: page to split 67 * key: key to insert 68 * data: data to insert 69 * flags: BIGKEY/BIGDATA flags 70 * ilen: insert length 71 * skip: index to leave open 72 * 73 * Returns: 74 * RET_ERROR, RET_SUCCESS 75 */ 76int 77__bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags, 78 size_t ilen, u_int32_t argskip) 79{ 80 BINTERNAL *bi; 81 BLEAF *bl, *tbl; 82 DBT a, b; 83 EPGNO *parent; 84 PAGE *h, *l, *r, *lchild, *rchild; 85 indx_t nxtindex; 86 u_int16_t skip; 87 u_int32_t n, nbytes, nksize; 88 int parentsplit; 89 char *dest; 90 91 /* 92 * Split the page into two pages, l and r. The split routines return 93 * a pointer to the page into which the key should be inserted and with 94 * skip set to the offset which should be used. Additionally, l and r 95 * are pinned. 96 */ 97 skip = argskip; 98 h = sp->pgno == P_ROOT ? 99 bt_root(t, sp, &l, &r, &skip, ilen) : 100 bt_page(t, sp, &l, &r, &skip, ilen); 101 if (h == NULL) 102 return (RET_ERROR); 103 104 /* 105 * Insert the new key/data pair into the leaf page. (Key inserts 106 * always cause a leaf page to split first.) 107 */ 108 h->linp[skip] = h->upper -= ilen; 109 dest = (char *)h + h->upper; 110 if (F_ISSET(t, R_RECNO)) 111 WR_RLEAF(dest, data, flags) 112 else 113 WR_BLEAF(dest, key, data, flags) 114 115 /* If the root page was split, make it look right. */ 116 if (sp->pgno == P_ROOT && 117 (F_ISSET(t, R_RECNO) ? 118 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 119 goto err2; 120 121 /* 122 * Now we walk the parent page stack -- a LIFO stack of the pages that 123 * were traversed when we searched for the page that split. Each stack 124 * entry is a page number and a page index offset. The offset is for 125 * the page traversed on the search. We've just split a page, so we 126 * have to insert a new key into the parent page. 127 * 128 * If the insert into the parent page causes it to split, may have to 129 * continue splitting all the way up the tree. We stop if the root 130 * splits or the page inserted into didn't have to split to hold the 131 * new key. Some algorithms replace the key for the old page as well 132 * as the new page. We don't, as there's no reason to believe that the 133 * first key on the old page is any better than the key we have, and, 134 * in the case of a key being placed at index 0 causing the split, the 135 * key is unavailable. 136 * 137 * There are a maximum of 5 pages pinned at any time. We keep the left 138 * and right pages pinned while working on the parent. The 5 are the 139 * two children, left parent and right parent (when the parent splits) 140 * and the root page or the overflow key page when calling bt_preserve. 141 * This code must make sure that all pins are released other than the 142 * root page or overflow page which is unlocked elsewhere. 143 */ 144 while ((parent = BT_POP(t)) != NULL) { 145 lchild = l; 146 rchild = r; 147 148 /* Get the parent page. */ 149 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 150 goto err2; 151 152 /* 153 * The new key goes ONE AFTER the index, because the split 154 * was to the right. 155 */ 156 skip = parent->index + 1; 157 158 /* 159 * Calculate the space needed on the parent page. 160 * 161 * Prefix trees: space hack when inserting into BINTERNAL 162 * pages. Retain only what's needed to distinguish between 163 * the new entry and the LAST entry on the page to its left. 164 * If the keys compare equal, retain the entire key. Note, 165 * we don't touch overflow keys, and the entire key must be 166 * retained for the next-to-left most key on the leftmost 167 * page of each level, or the search will fail. Applicable 168 * ONLY to internal pages that have leaf pages as children. 169 * Further reduction of the key between pairs of internal 170 * pages loses too much information. 171 */ 172 switch (rchild->flags & P_TYPE) { 173 case P_BINTERNAL: 174 bi = GETBINTERNAL(rchild, 0); 175 nbytes = NBINTERNAL(bi->ksize); 176 break; 177 case P_BLEAF: 178 bl = GETBLEAF(rchild, 0); 179 nbytes = NBINTERNAL(bl->ksize); 180 if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 181 (h->prevpg != P_INVALID || skip > 1)) { 182 tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1); 183 a.size = tbl->ksize; 184 a.data = tbl->bytes; 185 b.size = bl->ksize; 186 b.data = bl->bytes; 187 nksize = t->bt_pfx(&a, &b); 188 n = NBINTERNAL(nksize); 189 if (n < nbytes) { 190#ifdef STATISTICS 191 bt_pfxsaved += nbytes - n; 192#endif 193 nbytes = n; 194 } else 195 nksize = 0; 196 } else 197 nksize = 0; 198 break; 199 case P_RINTERNAL: 200 case P_RLEAF: 201 nbytes = NRINTERNAL; 202 break; 203 default: 204 abort(); 205 } 206 207 /* Split the parent page if necessary or shift the indices. */ 208 if ((u_int32_t)(h->upper - h->lower) < nbytes + sizeof(indx_t)) { 209 sp = h; 210 h = h->pgno == P_ROOT ? 211 bt_root(t, h, &l, &r, &skip, nbytes) : 212 bt_page(t, h, &l, &r, &skip, nbytes); 213 if (h == NULL) 214 goto err1; 215 parentsplit = 1; 216 } else { 217 if (skip < (nxtindex = NEXTINDEX(h))) 218 memmove(h->linp + skip + 1, h->linp + skip, 219 (nxtindex - skip) * sizeof(indx_t)); 220 h->lower += sizeof(indx_t); 221 parentsplit = 0; 222 } 223 224 /* Insert the key into the parent page. */ 225 switch (rchild->flags & P_TYPE) { 226 case P_BINTERNAL: 227 h->linp[skip] = h->upper -= nbytes; 228 dest = (char *)h + h->linp[skip]; 229 memmove(dest, bi, nbytes); 230 ((BINTERNAL *)dest)->pgno = rchild->pgno; 231 break; 232 case P_BLEAF: 233 h->linp[skip] = h->upper -= nbytes; 234 dest = (char *)h + h->linp[skip]; 235 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 236 rchild->pgno, bl->flags & P_BIGKEY); 237 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 238 if (bl->flags & P_BIGKEY) { 239 pgno_t pgno; 240 memcpy(&pgno, bl->bytes, sizeof(pgno)); 241 if (bt_preserve(t, pgno) == RET_ERROR) 242 goto err1; 243 } 244 break; 245 case P_RINTERNAL: 246 /* 247 * Update the left page count. If split 248 * added at index 0, fix the correct page. 249 */ 250 if (skip > 0) 251 dest = (char *)h + h->linp[skip - 1]; 252 else 253 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 254 ((RINTERNAL *)dest)->nrecs = rec_total(lchild); 255 ((RINTERNAL *)dest)->pgno = lchild->pgno; 256 257 /* Update the right page count. */ 258 h->linp[skip] = h->upper -= nbytes; 259 dest = (char *)h + h->linp[skip]; 260 ((RINTERNAL *)dest)->nrecs = rec_total(rchild); 261 ((RINTERNAL *)dest)->pgno = rchild->pgno; 262 break; 263 case P_RLEAF: 264 /* 265 * Update the left page count. If split 266 * added at index 0, fix the correct page. 267 */ 268 if (skip > 0) 269 dest = (char *)h + h->linp[skip - 1]; 270 else 271 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 272 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild); 273 ((RINTERNAL *)dest)->pgno = lchild->pgno; 274 275 /* Update the right page count. */ 276 h->linp[skip] = h->upper -= nbytes; 277 dest = (char *)h + h->linp[skip]; 278 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild); 279 ((RINTERNAL *)dest)->pgno = rchild->pgno; 280 break; 281 default: 282 abort(); 283 } 284 285 /* Unpin the held pages. */ 286 if (!parentsplit) { 287 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 288 break; 289 } 290 291 /* If the root page was split, make it look right. */ 292 if (sp->pgno == P_ROOT && 293 (F_ISSET(t, R_RECNO) ? 294 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 295 goto err1; 296 297 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 298 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 299 } 300 301 /* Unpin the held pages. */ 302 mpool_put(t->bt_mp, l, MPOOL_DIRTY); 303 mpool_put(t->bt_mp, r, MPOOL_DIRTY); 304 305 /* Clear any pages left on the stack. */ 306 return (RET_SUCCESS); 307 308 /* 309 * If something fails in the above loop we were already walking back 310 * up the tree and the tree is now inconsistent. Nothing much we can 311 * do about it but release any memory we're holding. 312 */ 313err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 314 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 315 316err2: mpool_put(t->bt_mp, l, 0); 317 mpool_put(t->bt_mp, r, 0); 318 __dbpanic(t->bt_dbp); 319 return (RET_ERROR); 320} 321 322/* 323 * BT_PAGE -- Split a non-root page of a btree. 324 * 325 * Parameters: 326 * t: tree 327 * h: root page 328 * lp: pointer to left page pointer 329 * rp: pointer to right page pointer 330 * skip: pointer to index to leave open 331 * ilen: insert length 332 * 333 * Returns: 334 * Pointer to page in which to insert or NULL on error. 335 */ 336static PAGE * 337bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 338{ 339 PAGE *l, *r, *tp; 340 pgno_t npg; 341 342#ifdef STATISTICS 343 ++bt_split; 344#endif 345 /* Put the new right page for the split into place. */ 346 if ((r = __bt_new(t, &npg)) == NULL) 347 return (NULL); 348 r->pgno = npg; 349 r->lower = BTDATAOFF; 350 r->upper = t->bt_psize; 351 r->nextpg = h->nextpg; 352 r->prevpg = h->pgno; 353 r->flags = h->flags & P_TYPE; 354 355 /* 356 * If we're splitting the last page on a level because we're appending 357 * a key to it (skip is NEXTINDEX()), it's likely that the data is 358 * sorted. Adding an empty page on the side of the level is less work 359 * and can push the fill factor much higher than normal. If we're 360 * wrong it's no big deal, we'll just do the split the right way next 361 * time. It may look like it's equally easy to do a similar hack for 362 * reverse sorted data, that is, split the tree left, but it's not. 363 * Don't even try. 364 */ 365 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 366#ifdef STATISTICS 367 ++bt_sortsplit; 368#endif 369 h->nextpg = r->pgno; 370 r->lower = BTDATAOFF + sizeof(indx_t); 371 *skip = 0; 372 *lp = h; 373 *rp = r; 374 return (r); 375 } 376 377 /* Put the new left page for the split into place. */ 378 if ((l = (PAGE *)calloc(1, t->bt_psize)) == NULL) { 379 mpool_put(t->bt_mp, r, 0); 380 return (NULL); 381 } 382 l->pgno = h->pgno; 383 l->nextpg = r->pgno; 384 l->prevpg = h->prevpg; 385 l->lower = BTDATAOFF; 386 l->upper = t->bt_psize; 387 l->flags = h->flags & P_TYPE; 388 389 /* Fix up the previous pointer of the page after the split page. */ 390 if (h->nextpg != P_INVALID) { 391 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 392 free(l); 393 /* XXX mpool_free(t->bt_mp, r->pgno); */ 394 return (NULL); 395 } 396 tp->prevpg = r->pgno; 397 mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 398 } 399 400 /* 401 * Split right. The key/data pairs aren't sorted in the btree page so 402 * it's simpler to copy the data from the split page onto two new pages 403 * instead of copying half the data to the right page and compacting 404 * the left page in place. Since the left page can't change, we have 405 * to swap the original and the allocated left page after the split. 406 */ 407 tp = bt_psplit(t, h, l, r, skip, ilen); 408 409 /* Move the new left page onto the old left page. */ 410 memmove(h, l, t->bt_psize); 411 if (tp == l) 412 tp = h; 413 free(l); 414 415 *lp = h; 416 *rp = r; 417 return (tp); 418} 419 420/* 421 * BT_ROOT -- Split the root page of a btree. 422 * 423 * Parameters: 424 * t: tree 425 * h: root page 426 * lp: pointer to left page pointer 427 * rp: pointer to right page pointer 428 * skip: pointer to index to leave open 429 * ilen: insert length 430 * 431 * Returns: 432 * Pointer to page in which to insert or NULL on error. 433 */ 434static PAGE * 435bt_root(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 436{ 437 PAGE *l, *r, *tp; 438 pgno_t lnpg, rnpg; 439 440#ifdef STATISTICS 441 ++bt_split; 442 ++bt_rootsplit; 443#endif 444 /* Put the new left and right pages for the split into place. */ 445 if ((l = __bt_new(t, &lnpg)) == NULL || 446 (r = __bt_new(t, &rnpg)) == NULL) 447 return (NULL); 448 l->pgno = lnpg; 449 r->pgno = rnpg; 450 l->nextpg = r->pgno; 451 r->prevpg = l->pgno; 452 l->prevpg = r->nextpg = P_INVALID; 453 l->lower = r->lower = BTDATAOFF; 454 l->upper = r->upper = t->bt_psize; 455 l->flags = r->flags = h->flags & P_TYPE; 456 457 /* Split the root page. */ 458 tp = bt_psplit(t, h, l, r, skip, ilen); 459 460 *lp = l; 461 *rp = r; 462 return (tp); 463} 464 465/* 466 * BT_RROOT -- Fix up the recno root page after it has been split. 467 * 468 * Parameters: 469 * t: tree 470 * h: root page 471 * l: left page 472 * r: right page 473 * 474 * Returns: 475 * RET_ERROR, RET_SUCCESS 476 */ 477static int 478bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 479{ 480 char *dest; 481 482 /* Insert the left and right keys, set the header information. */ 483 h->linp[0] = h->upper = t->bt_psize - NRINTERNAL; 484 dest = (char *)h + h->upper; 485 WR_RINTERNAL(dest, 486 l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno); 487 488 __PAST_END(h->linp, 1) = h->upper -= NRINTERNAL; 489 dest = (char *)h + h->upper; 490 WR_RINTERNAL(dest, 491 r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno); 492 493 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 494 495 /* Unpin the root page, set to recno internal page. */ 496 h->flags &= ~P_TYPE; 497 h->flags |= P_RINTERNAL; 498 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 499 500 return (RET_SUCCESS); 501} 502 503/* 504 * BT_BROOT -- Fix up the btree root page after it has been split. 505 * 506 * Parameters: 507 * t: tree 508 * h: root page 509 * l: left page 510 * r: right page 511 * 512 * Returns: 513 * RET_ERROR, RET_SUCCESS 514 */ 515static int 516bt_broot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 517{ 518 BINTERNAL *bi; 519 BLEAF *bl; 520 u_int32_t nbytes; 521 char *dest; 522 523 /* 524 * If the root page was a leaf page, change it into an internal page. 525 * We copy the key we split on (but not the key's data, in the case of 526 * a leaf page) to the new root page. 527 * 528 * The btree comparison code guarantees that the left-most key on any 529 * level of the tree is never used, so it doesn't need to be filled in. 530 */ 531 nbytes = NBINTERNAL(0); 532 h->linp[0] = h->upper = t->bt_psize - nbytes; 533 dest = (char *)h + h->upper; 534 WR_BINTERNAL(dest, 0, l->pgno, 0); 535 536 switch (h->flags & P_TYPE) { 537 case P_BLEAF: 538 bl = GETBLEAF(r, 0); 539 nbytes = NBINTERNAL(bl->ksize); 540 __PAST_END(h->linp, 1) = h->upper -= nbytes; 541 dest = (char *)h + h->upper; 542 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 543 memmove(dest, bl->bytes, bl->ksize); 544 545 /* 546 * If the key is on an overflow page, mark the overflow chain 547 * so it isn't deleted when the leaf copy of the key is deleted. 548 */ 549 if (bl->flags & P_BIGKEY) { 550 pgno_t pgno; 551 memcpy(&pgno, bl->bytes, sizeof(pgno)); 552 if (bt_preserve(t, pgno) == RET_ERROR) 553 return (RET_ERROR); 554 } 555 break; 556 case P_BINTERNAL: 557 bi = GETBINTERNAL(r, 0); 558 nbytes = NBINTERNAL(bi->ksize); 559 __PAST_END(h->linp, 1) = h->upper -= nbytes; 560 dest = (char *)h + h->upper; 561 memmove(dest, bi, nbytes); 562 ((BINTERNAL *)dest)->pgno = r->pgno; 563 break; 564 default: 565 abort(); 566 } 567 568 /* There are two keys on the page. */ 569 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 570 571 /* Unpin the root page, set to btree internal page. */ 572 h->flags &= ~P_TYPE; 573 h->flags |= P_BINTERNAL; 574 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 575 576 return (RET_SUCCESS); 577} 578 579/* 580 * BT_PSPLIT -- Do the real work of splitting the page. 581 * 582 * Parameters: 583 * t: tree 584 * h: page to be split 585 * l: page to put lower half of data 586 * r: page to put upper half of data 587 * pskip: pointer to index to leave open 588 * ilen: insert length 589 * 590 * Returns: 591 * Pointer to page in which to insert. 592 */ 593static PAGE * 594bt_psplit(BTREE *t, PAGE *h, PAGE *l, PAGE *r, indx_t *pskip, size_t ilen) 595{ 596 BINTERNAL *bi; 597 BLEAF *bl; 598 CURSOR *c; 599 RLEAF *rl; 600 PAGE *rval; 601 void *src; 602 indx_t full, half, nxt, off, skip, top, used; 603 u_int32_t nbytes; 604 int bigkeycnt, isbigkey; 605 606 /* 607 * Split the data to the left and right pages. Leave the skip index 608 * open. Additionally, make some effort not to split on an overflow 609 * key. This makes internal page processing faster and can save 610 * space as overflow keys used by internal pages are never deleted. 611 */ 612 bigkeycnt = 0; 613 skip = *pskip; 614 full = t->bt_psize - BTDATAOFF; 615 half = full / 2; 616 used = 0; 617 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 618 if (skip == off) { 619 nbytes = ilen; 620 isbigkey = 0; /* XXX: not really known. */ 621 } else 622 switch (h->flags & P_TYPE) { 623 case P_BINTERNAL: 624 src = bi = GETBINTERNAL(h, nxt); 625 nbytes = NBINTERNAL(bi->ksize); 626 isbigkey = bi->flags & P_BIGKEY; 627 break; 628 case P_BLEAF: 629 src = bl = GETBLEAF(h, nxt); 630 nbytes = NBLEAF(bl); 631 isbigkey = bl->flags & P_BIGKEY; 632 break; 633 case P_RINTERNAL: 634 src = GETRINTERNAL(h, nxt); 635 nbytes = NRINTERNAL; 636 isbigkey = 0; 637 break; 638 case P_RLEAF: 639 src = rl = GETRLEAF(h, nxt); 640 nbytes = NRLEAF(rl); 641 isbigkey = 0; 642 break; 643 default: 644 abort(); 645 } 646 647 /* 648 * If the key/data pairs are substantial fractions of the max 649 * possible size for the page, it's possible to get situations 650 * where we decide to try and copy too much onto the left page. 651 * Make sure that doesn't happen. 652 */ 653 if ((skip <= off && used + nbytes + sizeof(indx_t) >= full) || 654 nxt == top - 1) { 655 --off; 656 break; 657 } 658 659 /* Copy the key/data pair, if not the skipped index. */ 660 if (skip != off) { 661 ++nxt; 662 663 l->linp[off] = l->upper -= nbytes; 664 memmove((char *)l + l->upper, src, nbytes); 665 } 666 667 used += nbytes + sizeof(indx_t); 668 if (used >= half) { 669 if (!isbigkey || bigkeycnt == 3) 670 break; 671 else 672 ++bigkeycnt; 673 } 674 } 675 676 /* 677 * Off is the last offset that's valid for the left page. 678 * Nxt is the first offset to be placed on the right page. 679 */ 680 l->lower += (off + 1) * sizeof(indx_t); 681 682 /* 683 * If splitting the page that the cursor was on, the cursor has to be 684 * adjusted to point to the same record as before the split. If the 685 * cursor is at or past the skipped slot, the cursor is incremented by 686 * one. If the cursor is on the right page, it is decremented by the 687 * number of records split to the left page. 688 */ 689 c = &t->bt_cursor; 690 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 691 if (c->pg.index >= skip) 692 ++c->pg.index; 693 if (c->pg.index < nxt) /* Left page. */ 694 c->pg.pgno = l->pgno; 695 else { /* Right page. */ 696 c->pg.pgno = r->pgno; 697 c->pg.index -= nxt; 698 } 699 } 700 701 /* 702 * If the skipped index was on the left page, just return that page. 703 * Otherwise, adjust the skip index to reflect the new position on 704 * the right page. 705 */ 706 if (skip <= off) { 707 skip = MAX_PAGE_OFFSET; 708 rval = l; 709 } else { 710 rval = r; 711 *pskip -= nxt; 712 } 713 714 for (off = 0; nxt < top; ++off) { 715 if (skip == nxt) { 716 ++off; 717 skip = MAX_PAGE_OFFSET; 718 } 719 switch (h->flags & P_TYPE) { 720 case P_BINTERNAL: 721 src = bi = GETBINTERNAL(h, nxt); 722 nbytes = NBINTERNAL(bi->ksize); 723 break; 724 case P_BLEAF: 725 src = bl = GETBLEAF(h, nxt); 726 nbytes = NBLEAF(bl); 727 break; 728 case P_RINTERNAL: 729 src = GETRINTERNAL(h, nxt); 730 nbytes = NRINTERNAL; 731 break; 732 case P_RLEAF: 733 src = rl = GETRLEAF(h, nxt); 734 nbytes = NRLEAF(rl); 735 break; 736 default: 737 abort(); 738 } 739 ++nxt; 740 r->linp[off] = r->upper -= nbytes; 741 memmove((char *)r + r->upper, src, nbytes); 742 } 743 r->lower += off * sizeof(indx_t); 744 745 /* If the key is being appended to the page, adjust the index. */ 746 if (skip == top) 747 r->lower += sizeof(indx_t); 748 749 return (rval); 750} 751 752/* 753 * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 754 * 755 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 756 * record that references them gets deleted. Chains pointed to by internal 757 * pages never get deleted. This routine marks a chain as pointed to by an 758 * internal page. 759 * 760 * Parameters: 761 * t: tree 762 * pg: page number of first page in the chain. 763 * 764 * Returns: 765 * RET_SUCCESS, RET_ERROR. 766 */ 767static int 768bt_preserve(BTREE *t, pgno_t pg) 769{ 770 PAGE *h; 771 772 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 773 return (RET_ERROR); 774 h->flags |= P_PRESERVE; 775 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 776 return (RET_SUCCESS); 777} 778 779/* 780 * REC_TOTAL -- Return the number of recno entries below a page. 781 * 782 * Parameters: 783 * h: page 784 * 785 * Returns: 786 * The number of recno entries below a page. 787 * 788 * XXX 789 * These values could be set by the bt_psplit routine. The problem is that the 790 * entry has to be popped off of the stack etc. or the values have to be passed 791 * all the way back to bt_split/bt_rroot and it's not very clean. 792 */ 793static recno_t 794rec_total(PAGE *h) 795{ 796 recno_t recs; 797 indx_t nxt, top; 798 799 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 800 recs += GETRINTERNAL(h, nxt)->nrecs; 801 return (recs); 802} 803