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 * 3. 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 * @(#)bt_split.c 8.10 (Berkeley) 1/9/95 33 * $FreeBSD: head/lib/libc/db/btree/bt_split.c 223262 2011-06-18 13:56:33Z benl $ 34 */ 35 36 #include <sys/types.h> 37 #include <sys/param.h> 38 39 #include <limits.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 44 #include <db.h> 45 #include "btree.h" 46 47 static int bt_broot(BTREE *, PAGE *, PAGE *, PAGE *); 48 static PAGE *bt_page(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 49 static int bt_preserve(BTREE *, pgno_t); 50 static PAGE *bt_psplit(BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t); 51 static PAGE *bt_root(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 52 static int bt_rroot(BTREE *, PAGE *, PAGE *, PAGE *); 53 static recno_t rec_total(PAGE *); 54 55 #ifdef STATISTICS 56 unsigned long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 57 #endif 58 59 /* 60 * __BT_SPLIT -- Split the tree. 61 * 62 * Parameters: 63 * t: tree 64 * sp: page to split 65 * key: key to insert 66 * data: data to insert 67 * flags: BIGKEY/BIGDATA flags 68 * ilen: insert length 69 * skip: index to leave open 70 * 71 * Returns: 72 * RET_ERROR, RET_SUCCESS 73 */ 74 int 75 __bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags, 76 size_t ilen, uint32_t argskip) 77 { 78 BINTERNAL *bi; 79 BLEAF *bl, *tbl; 80 DBT a, b; 81 EPGNO *parent; 82 PAGE *h, *l, *r, *lchild, *rchild; 83 indx_t nxtindex; 84 uint16_t skip; 85 uint32_t n, nbytes, nksize; 86 int parentsplit; 87 char *dest; 88 89 /* 90 * Split the page into two pages, l and r. The split routines return 91 * a pointer to the page into which the key should be inserted and with 92 * skip set to the offset which should be used. Additionally, l and r 93 * are pinned. 94 */ 95 skip = argskip; 96 h = sp->pgno == P_ROOT ? 97 bt_root(t, sp, &l, &r, &skip, ilen) : 98 bt_page(t, sp, &l, &r, &skip, ilen); 99 if (h == NULL) 100 return (RET_ERROR); 101 102 /* 103 * Insert the new key/data pair into the leaf page. (Key inserts 104 * always cause a leaf page to split first.) 105 */ 106 h->linp[skip] = h->upper -= ilen; 107 dest = (char *)h + h->upper; 108 if (F_ISSET(t, R_RECNO)) 109 WR_RLEAF(dest, data, flags) 110 else 111 WR_BLEAF(dest, key, data, flags) 112 113 /* If the root page was split, make it look right. */ 114 if (sp->pgno == P_ROOT && 115 (F_ISSET(t, R_RECNO) ? 116 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 117 goto err2; 118 119 /* 120 * Now we walk the parent page stack -- a LIFO stack of the pages that 121 * were traversed when we searched for the page that split. Each stack 122 * entry is a page number and a page index offset. The offset is for 123 * the page traversed on the search. We've just split a page, so we 124 * have to insert a new key into the parent page. 125 * 126 * If the insert into the parent page causes it to split, may have to 127 * continue splitting all the way up the tree. We stop if the root 128 * splits or the page inserted into didn't have to split to hold the 129 * new key. Some algorithms replace the key for the old page as well 130 * as the new page. We don't, as there's no reason to believe that the 131 * first key on the old page is any better than the key we have, and, 132 * in the case of a key being placed at index 0 causing the split, the 133 * key is unavailable. 134 * 135 * There are a maximum of 5 pages pinned at any time. We keep the left 136 * and right pages pinned while working on the parent. The 5 are the 137 * two children, left parent and right parent (when the parent splits) 138 * and the root page or the overflow key page when calling bt_preserve. 139 * This code must make sure that all pins are released other than the 140 * root page or overflow page which is unlocked elsewhere. 141 */ 142 while ((parent = BT_POP(t)) != NULL) { 143 lchild = l; 144 rchild = r; 145 146 /* Get the parent page. */ 147 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 148 goto err2; 149 150 /* 151 * The new key goes ONE AFTER the index, because the split 152 * was to the right. 153 */ 154 skip = parent->index + 1; 155 156 /* 157 * Calculate the space needed on the parent page. 158 * 159 * Prefix trees: space hack when inserting into BINTERNAL 160 * pages. Retain only what's needed to distinguish between 161 * the new entry and the LAST entry on the page to its left. 162 * If the keys compare equal, retain the entire key. Note, 163 * we don't touch overflow keys, and the entire key must be 164 * retained for the next-to-left most key on the leftmost 165 * page of each level, or the search will fail. Applicable 166 * ONLY to internal pages that have leaf pages as children. 167 * Further reduction of the key between pairs of internal 168 * pages loses too much information. 169 */ 170 switch (rchild->flags & P_TYPE) { 171 case P_BINTERNAL: 172 bi = GETBINTERNAL(rchild, 0); 173 nbytes = NBINTERNAL(bi->ksize); 174 break; 175 case P_BLEAF: 176 bl = GETBLEAF(rchild, 0); 177 nbytes = NBINTERNAL(bl->ksize); 178 if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 179 (h->prevpg != P_INVALID || skip > 1)) { 180 tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1); 181 a.size = tbl->ksize; 182 a.data = tbl->bytes; 183 b.size = bl->ksize; 184 b.data = bl->bytes; 185 nksize = t->bt_pfx(&a, &b); 186 n = NBINTERNAL(nksize); 187 if (n < nbytes) { 188 #ifdef STATISTICS 189 bt_pfxsaved += nbytes - n; 190 #endif 191 nbytes = n; 192 } else 193 nksize = 0; 194 } else 195 nksize = 0; 196 break; 197 case P_RINTERNAL: 198 case P_RLEAF: 199 nbytes = NRINTERNAL; 200 break; 201 default: 202 abort(); 203 } 204 205 /* Split the parent page if necessary or shift the indices. */ 206 if ((uint32_t)(h->upper - h->lower) < nbytes + sizeof(indx_t)) { 207 sp = h; 208 h = h->pgno == P_ROOT ? 209 bt_root(t, h, &l, &r, &skip, nbytes) : 210 bt_page(t, h, &l, &r, &skip, nbytes); 211 if (h == NULL) 212 goto err1; 213 parentsplit = 1; 214 } else { 215 if (skip < (nxtindex = NEXTINDEX(h))) 216 memmove(h->linp + skip + 1, h->linp + skip, 217 (nxtindex - skip) * sizeof(indx_t)); 218 h->lower += sizeof(indx_t); 219 parentsplit = 0; 220 } 221 222 /* Insert the key into the parent page. */ 223 switch (rchild->flags & P_TYPE) { 224 case P_BINTERNAL: 225 h->linp[skip] = h->upper -= nbytes; 226 dest = (char *)h + h->linp[skip]; 227 memmove(dest, bi, nbytes); 228 ((BINTERNAL *)dest)->pgno = rchild->pgno; 229 break; 230 case P_BLEAF: 231 h->linp[skip] = h->upper -= nbytes; 232 dest = (char *)h + h->linp[skip]; 233 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 234 rchild->pgno, bl->flags & P_BIGKEY); 235 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 236 if (bl->flags & P_BIGKEY && 237 bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR) 238 goto err1; 239 break; 240 case P_RINTERNAL: 241 /* 242 * Update the left page count. If split 243 * added at index 0, fix the correct page. 244 */ 245 if (skip > 0) 246 dest = (char *)h + h->linp[skip - 1]; 247 else 248 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 249 ((RINTERNAL *)dest)->nrecs = rec_total(lchild); 250 ((RINTERNAL *)dest)->pgno = lchild->pgno; 251 252 /* Update the right page count. */ 253 h->linp[skip] = h->upper -= nbytes; 254 dest = (char *)h + h->linp[skip]; 255 ((RINTERNAL *)dest)->nrecs = rec_total(rchild); 256 ((RINTERNAL *)dest)->pgno = rchild->pgno; 257 break; 258 case P_RLEAF: 259 /* 260 * Update the left page count. If split 261 * added at index 0, fix the correct page. 262 */ 263 if (skip > 0) 264 dest = (char *)h + h->linp[skip - 1]; 265 else 266 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 267 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild); 268 ((RINTERNAL *)dest)->pgno = lchild->pgno; 269 270 /* Update the right page count. */ 271 h->linp[skip] = h->upper -= nbytes; 272 dest = (char *)h + h->linp[skip]; 273 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild); 274 ((RINTERNAL *)dest)->pgno = rchild->pgno; 275 break; 276 default: 277 abort(); 278 } 279 280 /* Unpin the held pages. */ 281 if (!parentsplit) { 282 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 283 break; 284 } 285 286 /* If the root page was split, make it look right. */ 287 if (sp->pgno == P_ROOT && 288 (F_ISSET(t, R_RECNO) ? 289 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 290 goto err1; 291 292 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 293 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 294 } 295 296 /* Unpin the held pages. */ 297 mpool_put(t->bt_mp, l, MPOOL_DIRTY); 298 mpool_put(t->bt_mp, r, MPOOL_DIRTY); 299 300 /* Clear any pages left on the stack. */ 301 return (RET_SUCCESS); 302 303 /* 304 * If something fails in the above loop we were already walking back 305 * up the tree and the tree is now inconsistent. Nothing much we can 306 * do about it but release any memory we're holding. 307 */ 308 err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 309 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 310 311 err2: mpool_put(t->bt_mp, l, 0); 312 mpool_put(t->bt_mp, r, 0); 313 __dbpanic(t->bt_dbp); 314 return (RET_ERROR); 315 } 316 317 /* 318 * BT_PAGE -- Split a non-root page of a btree. 319 * 320 * Parameters: 321 * t: tree 322 * h: root page 323 * lp: pointer to left page pointer 324 * rp: pointer to right page pointer 325 * skip: pointer to index to leave open 326 * ilen: insert length 327 * 328 * Returns: 329 * Pointer to page in which to insert or NULL on error. 330 */ 331 static PAGE * 332 bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 333 { 334 PAGE *l, *r, *tp; 335 pgno_t npg; 336 337 #ifdef STATISTICS 338 ++bt_split; 339 #endif 340 /* Put the new right page for the split into place. */ 341 if ((r = __bt_new(t, &npg)) == NULL) 342 return (NULL); 343 r->pgno = npg; 344 r->lower = BTDATAOFF; 345 r->upper = t->bt_psize; 346 r->nextpg = h->nextpg; 347 r->prevpg = h->pgno; 348 r->flags = h->flags & P_TYPE; 349 350 /* 351 * If we're splitting the last page on a level because we're appending 352 * a key to it (skip is NEXTINDEX()), it's likely that the data is 353 * sorted. Adding an empty page on the side of the level is less work 354 * and can push the fill factor much higher than normal. If we're 355 * wrong it's no big deal, we'll just do the split the right way next 356 * time. It may look like it's equally easy to do a similar hack for 357 * reverse sorted data, that is, split the tree left, but it's not. 358 * Don't even try. 359 */ 360 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 361 #ifdef STATISTICS 362 ++bt_sortsplit; 363 #endif 364 h->nextpg = r->pgno; 365 r->lower = BTDATAOFF + sizeof(indx_t); 366 *skip = 0; 367 *lp = h; 368 *rp = r; 369 return (r); 370 } 371 372 /* Put the new left page for the split into place. */ 373 if ((l = (PAGE *)calloc(1, t->bt_psize)) == NULL) { 374 mpool_put(t->bt_mp, r, 0); 375 return (NULL); 376 } 377 l->pgno = h->pgno; 378 l->nextpg = r->pgno; 379 l->prevpg = h->prevpg; 380 l->lower = BTDATAOFF; 381 l->upper = t->bt_psize; 382 l->flags = h->flags & P_TYPE; 383 384 /* Fix up the previous pointer of the page after the split page. */ 385 if (h->nextpg != P_INVALID) { 386 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 387 free(l); 388 /* XXX mpool_free(t->bt_mp, r->pgno); */ 389 return (NULL); 390 } 391 tp->prevpg = r->pgno; 392 mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 393 } 394 395 /* 396 * Split right. The key/data pairs aren't sorted in the btree page so 397 * it's simpler to copy the data from the split page onto two new pages 398 * instead of copying half the data to the right page and compacting 399 * the left page in place. Since the left page can't change, we have 400 * to swap the original and the allocated left page after the split. 401 */ 402 tp = bt_psplit(t, h, l, r, skip, ilen); 403 404 /* Move the new left page onto the old left page. */ 405 memmove(h, l, t->bt_psize); 406 if (tp == l) 407 tp = h; 408 free(l); 409 410 *lp = h; 411 *rp = r; 412 return (tp); 413 } 414 415 /* 416 * BT_ROOT -- Split the root page of a btree. 417 * 418 * Parameters: 419 * t: tree 420 * h: root page 421 * lp: pointer to left page pointer 422 * rp: pointer to right page pointer 423 * skip: pointer to index to leave open 424 * ilen: insert length 425 * 426 * Returns: 427 * Pointer to page in which to insert or NULL on error. 428 */ 429 static PAGE * 430 bt_root(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 431 { 432 PAGE *l, *r, *tp; 433 pgno_t lnpg, rnpg; 434 435 #ifdef STATISTICS 436 ++bt_split; 437 ++bt_rootsplit; 438 #endif 439 /* Put the new left and right pages for the split into place. */ 440 if ((l = __bt_new(t, &lnpg)) == NULL || 441 (r = __bt_new(t, &rnpg)) == NULL) 442 return (NULL); 443 l->pgno = lnpg; 444 r->pgno = rnpg; 445 l->nextpg = r->pgno; 446 r->prevpg = l->pgno; 447 l->prevpg = r->nextpg = P_INVALID; 448 l->lower = r->lower = BTDATAOFF; 449 l->upper = r->upper = t->bt_psize; 450 l->flags = r->flags = h->flags & P_TYPE; 451 452 /* Split the root page. */ 453 tp = bt_psplit(t, h, l, r, skip, ilen); 454 455 *lp = l; 456 *rp = r; 457 return (tp); 458 } 459 460 /* 461 * BT_RROOT -- Fix up the recno root page after it has been split. 462 * 463 * Parameters: 464 * t: tree 465 * h: root page 466 * l: left page 467 * r: right page 468 * 469 * Returns: 470 * RET_ERROR, RET_SUCCESS 471 */ 472 static int 473 bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 474 { 475 char *dest; 476 477 /* Insert the left and right keys, set the header information. */ 478 h->linp[0] = h->upper = t->bt_psize - NRINTERNAL; 479 dest = (char *)h + h->upper; 480 WR_RINTERNAL(dest, 481 l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno); 482 483 __PAST_END(h->linp, 1) = h->upper -= NRINTERNAL; 484 dest = (char *)h + h->upper; 485 WR_RINTERNAL(dest, 486 r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno); 487 488 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 489 490 /* Unpin the root page, set to recno internal page. */ 491 h->flags &= ~P_TYPE; 492 h->flags |= P_RINTERNAL; 493 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 494 495 return (RET_SUCCESS); 496 } 497 498 /* 499 * BT_BROOT -- Fix up the btree root page after it has been split. 500 * 501 * Parameters: 502 * t: tree 503 * h: root page 504 * l: left page 505 * r: right page 506 * 507 * Returns: 508 * RET_ERROR, RET_SUCCESS 509 */ 510 static int 511 bt_broot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 512 { 513 BINTERNAL *bi; 514 BLEAF *bl; 515 uint32_t nbytes; 516 char *dest; 517 518 /* 519 * If the root page was a leaf page, change it into an internal page. 520 * We copy the key we split on (but not the key's data, in the case of 521 * a leaf page) to the new root page. 522 * 523 * The btree comparison code guarantees that the left-most key on any 524 * level of the tree is never used, so it doesn't need to be filled in. 525 */ 526 nbytes = NBINTERNAL(0); 527 h->linp[0] = h->upper = t->bt_psize - nbytes; 528 dest = (char *)h + h->upper; 529 WR_BINTERNAL(dest, 0, l->pgno, 0); 530 531 switch (h->flags & P_TYPE) { 532 case P_BLEAF: 533 bl = GETBLEAF(r, 0); 534 nbytes = NBINTERNAL(bl->ksize); 535 __PAST_END(h->linp, 1) = h->upper -= nbytes; 536 dest = (char *)h + h->upper; 537 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 538 memmove(dest, bl->bytes, bl->ksize); 539 540 /* 541 * If the key is on an overflow page, mark the overflow chain 542 * so it isn't deleted when the leaf copy of the key is deleted. 543 */ 544 if (bl->flags & P_BIGKEY && 545 bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR) 546 return (RET_ERROR); 547 break; 548 case P_BINTERNAL: 549 bi = GETBINTERNAL(r, 0); 550 nbytes = NBINTERNAL(bi->ksize); 551 __PAST_END(h->linp, 1) = h->upper -= nbytes; 552 dest = (char *)h + h->upper; 553 memmove(dest, bi, nbytes); 554 ((BINTERNAL *)dest)->pgno = r->pgno; 555 break; 556 default: 557 abort(); 558 } 559 560 /* There are two keys on the page. */ 561 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 562 563 /* Unpin the root page, set to btree internal page. */ 564 h->flags &= ~P_TYPE; 565 h->flags |= P_BINTERNAL; 566 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 567 568 return (RET_SUCCESS); 569 } 570 571 /* 572 * BT_PSPLIT -- Do the real work of splitting the page. 573 * 574 * Parameters: 575 * t: tree 576 * h: page to be split 577 * l: page to put lower half of data 578 * r: page to put upper half of data 579 * pskip: pointer to index to leave open 580 * ilen: insert length 581 * 582 * Returns: 583 * Pointer to page in which to insert. 584 */ 585 static PAGE * 586 bt_psplit(BTREE *t, PAGE *h, PAGE *l, PAGE *r, indx_t *pskip, size_t ilen) 587 { 588 BINTERNAL *bi; 589 BLEAF *bl; 590 CURSOR *c; 591 RLEAF *rl; 592 PAGE *rval; 593 void *src; 594 indx_t full, half, nxt, off, skip, top, used; 595 uint32_t nbytes; 596 int bigkeycnt, isbigkey; 597 598 /* 599 * Split the data to the left and right pages. Leave the skip index 600 * open. Additionally, make some effort not to split on an overflow 601 * key. This makes internal page processing faster and can save 602 * space as overflow keys used by internal pages are never deleted. 603 */ 604 bigkeycnt = 0; 605 skip = *pskip; 606 full = t->bt_psize - BTDATAOFF; 607 half = full / 2; 608 used = 0; 609 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 610 if (skip == off) { 611 nbytes = ilen; 612 isbigkey = 0; /* XXX: not really known. */ 613 } else 614 switch (h->flags & P_TYPE) { 615 case P_BINTERNAL: 616 src = bi = GETBINTERNAL(h, nxt); 617 nbytes = NBINTERNAL(bi->ksize); 618 isbigkey = bi->flags & P_BIGKEY; 619 break; 620 case P_BLEAF: 621 src = bl = GETBLEAF(h, nxt); 622 nbytes = NBLEAF(bl); 623 isbigkey = bl->flags & P_BIGKEY; 624 break; 625 case P_RINTERNAL: 626 src = GETRINTERNAL(h, nxt); 627 nbytes = NRINTERNAL; 628 isbigkey = 0; 629 break; 630 case P_RLEAF: 631 src = rl = GETRLEAF(h, nxt); 632 nbytes = NRLEAF(rl); 633 isbigkey = 0; 634 break; 635 default: 636 abort(); 637 } 638 639 /* 640 * If the key/data pairs are substantial fractions of the max 641 * possible size for the page, it's possible to get situations 642 * where we decide to try and copy too much onto the left page. 643 * Make sure that doesn't happen. 644 */ 645 if ((skip <= off && used + nbytes + sizeof(indx_t) >= full) || 646 nxt == top - 1) { 647 --off; 648 break; 649 } 650 651 /* Copy the key/data pair, if not the skipped index. */ 652 if (skip != off) { 653 ++nxt; 654 655 l->linp[off] = l->upper -= nbytes; 656 memmove((char *)l + l->upper, src, nbytes); 657 } 658 659 used += nbytes + sizeof(indx_t); 660 if (used >= half) { 661 if (!isbigkey || bigkeycnt == 3) 662 break; 663 else 664 ++bigkeycnt; 665 } 666 } 667 668 /* 669 * Off is the last offset that's valid for the left page. 670 * Nxt is the first offset to be placed on the right page. 671 */ 672 l->lower += (off + 1) * sizeof(indx_t); 673 674 /* 675 * If splitting the page that the cursor was on, the cursor has to be 676 * adjusted to point to the same record as before the split. If the 677 * cursor is at or past the skipped slot, the cursor is incremented by 678 * one. If the cursor is on the right page, it is decremented by the 679 * number of records split to the left page. 680 */ 681 c = &t->bt_cursor; 682 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 683 if (c->pg.index >= skip) 684 ++c->pg.index; 685 if (c->pg.index < nxt) /* Left page. */ 686 c->pg.pgno = l->pgno; 687 else { /* Right page. */ 688 c->pg.pgno = r->pgno; 689 c->pg.index -= nxt; 690 } 691 } 692 693 /* 694 * If the skipped index was on the left page, just return that page. 695 * Otherwise, adjust the skip index to reflect the new position on 696 * the right page. 697 */ 698 if (skip <= off) { 699 skip = MAX_PAGE_OFFSET; 700 rval = l; 701 } else { 702 rval = r; 703 *pskip -= nxt; 704 } 705 706 for (off = 0; nxt < top; ++off) { 707 if (skip == nxt) { 708 ++off; 709 skip = MAX_PAGE_OFFSET; 710 } 711 switch (h->flags & P_TYPE) { 712 case P_BINTERNAL: 713 src = bi = GETBINTERNAL(h, nxt); 714 nbytes = NBINTERNAL(bi->ksize); 715 break; 716 case P_BLEAF: 717 src = bl = GETBLEAF(h, nxt); 718 nbytes = NBLEAF(bl); 719 break; 720 case P_RINTERNAL: 721 src = GETRINTERNAL(h, nxt); 722 nbytes = NRINTERNAL; 723 break; 724 case P_RLEAF: 725 src = rl = GETRLEAF(h, nxt); 726 nbytes = NRLEAF(rl); 727 break; 728 default: 729 abort(); 730 } 731 ++nxt; 732 r->linp[off] = r->upper -= nbytes; 733 memmove((char *)r + r->upper, src, nbytes); 734 } 735 r->lower += off * sizeof(indx_t); 736 737 /* If the key is being appended to the page, adjust the index. */ 738 if (skip == top) 739 r->lower += sizeof(indx_t); 740 741 return (rval); 742 } 743 744 /* 745 * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 746 * 747 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 748 * record that references them gets deleted. Chains pointed to by internal 749 * pages never get deleted. This routine marks a chain as pointed to by an 750 * internal page. 751 * 752 * Parameters: 753 * t: tree 754 * pg: page number of first page in the chain. 755 * 756 * Returns: 757 * RET_SUCCESS, RET_ERROR. 758 */ 759 static int 760 bt_preserve(BTREE *t, pgno_t pg) 761 { 762 PAGE *h; 763 764 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 765 return (RET_ERROR); 766 h->flags |= P_PRESERVE; 767 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 768 return (RET_SUCCESS); 769 } 770 771 /* 772 * REC_TOTAL -- Return the number of recno entries below a page. 773 * 774 * Parameters: 775 * h: page 776 * 777 * Returns: 778 * The number of recno entries below a page. 779 * 780 * XXX 781 * These values could be set by the bt_psplit routine. The problem is that the 782 * entry has to be popped off of the stack etc. or the values have to be passed 783 * all the way back to bt_split/bt_rroot and it's not very clean. 784 */ 785 static recno_t 786 rec_total(PAGE *h) 787 { 788 recno_t recs; 789 indx_t nxt, top; 790 791 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 792 recs += GETRINTERNAL(h, nxt)->nrecs; 793 return (recs); 794 } 795