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