1 #pragma ident "%Z%%M% %I% %E% SMI" 2 3 /*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Mike Olson. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 static char sccsid[] = "@(#)bt_split.c 8.10 (Berkeley) 1/9/95"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <sys/types.h> 44 45 #include <limits.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 50 #include "db-int.h" 51 #include "btree.h" 52 53 static int bt_broot __P((BTREE *, PAGE *, PAGE *, PAGE *)); 54 static PAGE *bt_page 55 __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t)); 56 static int bt_preserve __P((BTREE *, db_pgno_t)); 57 static PAGE *bt_psplit 58 __P((BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t)); 59 static PAGE *bt_root 60 __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t)); 61 static int bt_rroot __P((BTREE *, PAGE *, PAGE *, PAGE *)); 62 static recno_t rec_total __P((PAGE *)); 63 64 #ifdef STATISTICS 65 u_long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 66 #endif 67 68 /* 69 * __BT_SPLIT -- Split the tree. 70 * 71 * Parameters: 72 * t: tree 73 * sp: page to split 74 * key: key to insert 75 * data: data to insert 76 * flags: BIGKEY/BIGDATA flags 77 * ilen: insert length 78 * skip: index to leave open 79 * 80 * Returns: 81 * RET_ERROR, RET_SUCCESS 82 */ 83 int 84 __bt_split(t, sp, key, data, flags, ilen, argskip) 85 BTREE *t; 86 PAGE *sp; 87 const DBT *key, *data; 88 int flags; 89 size_t ilen; 90 u_int32_t argskip; 91 { 92 BINTERNAL *bi; 93 BLEAF *bl, *tbl; 94 DBT a, b; 95 EPGNO *parent; 96 PAGE *h, *l, *r, *lchild, *rchild; 97 indx_t nxtindex; 98 u_int16_t skip; 99 u_int32_t n, nbytes, nksize; 100 int parentsplit; 101 char *dest; 102 103 /* 104 * Split the page into two pages, l and r. The split routines return 105 * a pointer to the page into which the key should be inserted and with 106 * skip set to the offset which should be used. Additionally, l and r 107 * are pinned. 108 */ 109 skip = argskip; 110 h = sp->pgno == P_ROOT ? 111 bt_root(t, sp, &l, &r, &skip, ilen) : 112 bt_page(t, sp, &l, &r, &skip, ilen); 113 if (h == NULL) 114 return (RET_ERROR); 115 116 /* 117 * Insert the new key/data pair into the leaf page. (Key inserts 118 * always cause a leaf page to split first.) 119 */ 120 h->linp[skip] = h->upper -= ilen; 121 dest = (char *)h + h->upper; 122 if (F_ISSET(t, R_RECNO)) 123 WR_RLEAF(dest, data, flags) 124 else 125 WR_BLEAF(dest, key, data, flags) 126 127 /* If the root page was split, make it look right. */ 128 if (sp->pgno == P_ROOT && 129 (F_ISSET(t, R_RECNO) ? 130 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 131 goto err2; 132 133 /* 134 * Now we walk the parent page stack -- a LIFO stack of the pages that 135 * were traversed when we searched for the page that split. Each stack 136 * entry is a page number and a page index offset. The offset is for 137 * the page traversed on the search. We've just split a page, so we 138 * have to insert a new key into the parent page. 139 * 140 * If the insert into the parent page causes it to split, may have to 141 * continue splitting all the way up the tree. We stop if the root 142 * splits or the page inserted into didn't have to split to hold the 143 * new key. Some algorithms replace the key for the old page as well 144 * as the new page. We don't, as there's no reason to believe that the 145 * first key on the old page is any better than the key we have, and, 146 * in the case of a key being placed at index 0 causing the split, the 147 * key is unavailable. 148 * 149 * There are a maximum of 5 pages pinned at any time. We keep the left 150 * and right pages pinned while working on the parent. The 5 are the 151 * two children, left parent and right parent (when the parent splits) 152 * and the root page or the overflow key page when calling bt_preserve. 153 * This code must make sure that all pins are released other than the 154 * root page or overflow page which is unlocked elsewhere. 155 */ 156 while ((parent = BT_POP(t)) != NULL) { 157 lchild = l; 158 rchild = r; 159 160 /* Get the parent page. */ 161 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 162 goto err2; 163 164 /* 165 * The new key goes ONE AFTER the index, because the split 166 * was to the right. 167 */ 168 skip = parent->index + 1; 169 170 /* 171 * Calculate the space needed on the parent page. 172 * 173 * Prefix trees: space hack when inserting into BINTERNAL 174 * pages. Retain only what's needed to distinguish between 175 * the new entry and the LAST entry on the page to its left. 176 * If the keys compare equal, retain the entire key. Note, 177 * we don't touch overflow keys, and the entire key must be 178 * retained for the next-to-left most key on the leftmost 179 * page of each level, or the search will fail. Applicable 180 * ONLY to internal pages that have leaf pages as children. 181 * Further reduction of the key between pairs of internal 182 * pages loses too much information. 183 */ 184 switch (rchild->flags & P_TYPE) { 185 case P_BINTERNAL: 186 bi = GETBINTERNAL(rchild, 0); 187 nbytes = NBINTERNAL(bi->ksize); 188 break; 189 case P_BLEAF: 190 bl = GETBLEAF(rchild, 0); 191 nbytes = NBINTERNAL(bl->ksize); 192 if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 193 (h->prevpg != P_INVALID || skip > 1)) { 194 tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1); 195 a.size = tbl->ksize; 196 a.data = tbl->bytes; 197 b.size = bl->ksize; 198 b.data = bl->bytes; 199 nksize = t->bt_pfx(&a, &b); 200 n = NBINTERNAL(nksize); 201 if (n < nbytes) { 202 #ifdef STATISTICS 203 bt_pfxsaved += nbytes - n; 204 #endif 205 nbytes = n; 206 } else 207 nksize = 0; 208 } else 209 nksize = 0; 210 break; 211 case P_RINTERNAL: 212 case P_RLEAF: 213 nbytes = NRINTERNAL; 214 break; 215 default: 216 abort(); 217 } 218 219 /* Split the parent page if necessary or shift the indices. */ 220 if (h->upper - h->lower < nbytes + sizeof(indx_t)) { 221 sp = h; 222 h = h->pgno == P_ROOT ? 223 bt_root(t, h, &l, &r, &skip, nbytes) : 224 bt_page(t, h, &l, &r, &skip, nbytes); 225 if (h == NULL) 226 goto err1; 227 parentsplit = 1; 228 } else { 229 if (skip < (nxtindex = NEXTINDEX(h))) 230 memmove(h->linp + skip + 1, h->linp + skip, 231 (nxtindex - skip) * sizeof(indx_t)); 232 h->lower += sizeof(indx_t); 233 parentsplit = 0; 234 } 235 236 /* Insert the key into the parent page. */ 237 switch (rchild->flags & P_TYPE) { 238 case P_BINTERNAL: 239 h->linp[skip] = h->upper -= nbytes; 240 dest = (char *)h + h->linp[skip]; 241 memmove(dest, bi, nbytes); 242 ((BINTERNAL *)dest)->pgno = rchild->pgno; 243 break; 244 case P_BLEAF: 245 h->linp[skip] = h->upper -= nbytes; 246 dest = (char *)h + h->linp[skip]; 247 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 248 rchild->pgno, bl->flags & P_BIGKEY); 249 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 250 if (bl->flags & P_BIGKEY && 251 bt_preserve(t, *(db_pgno_t *)bl->bytes) == RET_ERROR) 252 goto err1; 253 break; 254 case P_RINTERNAL: 255 /* 256 * Update the left page count. If split 257 * added at index 0, fix the correct page. 258 */ 259 if (skip > 0) 260 dest = (char *)h + h->linp[skip - 1]; 261 else 262 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 263 ((RINTERNAL *)dest)->nrecs = rec_total(lchild); 264 ((RINTERNAL *)dest)->pgno = lchild->pgno; 265 266 /* Update the right page count. */ 267 h->linp[skip] = h->upper -= nbytes; 268 dest = (char *)h + h->linp[skip]; 269 ((RINTERNAL *)dest)->nrecs = rec_total(rchild); 270 ((RINTERNAL *)dest)->pgno = rchild->pgno; 271 break; 272 case P_RLEAF: 273 /* 274 * Update the left page count. If split 275 * added at index 0, fix the correct page. 276 */ 277 if (skip > 0) 278 dest = (char *)h + h->linp[skip - 1]; 279 else 280 dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 281 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild); 282 ((RINTERNAL *)dest)->pgno = lchild->pgno; 283 284 /* Update the right page count. */ 285 h->linp[skip] = h->upper -= nbytes; 286 dest = (char *)h + h->linp[skip]; 287 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild); 288 ((RINTERNAL *)dest)->pgno = rchild->pgno; 289 break; 290 default: 291 abort(); 292 } 293 294 /* Unpin the held pages. */ 295 if (!parentsplit) { 296 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 297 break; 298 } 299 300 /* If the root page was split, make it look right. */ 301 if (sp->pgno == P_ROOT && 302 (F_ISSET(t, R_RECNO) ? 303 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 304 goto err1; 305 306 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 307 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 308 } 309 310 /* Unpin the held pages. */ 311 mpool_put(t->bt_mp, l, MPOOL_DIRTY); 312 mpool_put(t->bt_mp, r, MPOOL_DIRTY); 313 314 /* Clear any pages left on the stack. */ 315 return (RET_SUCCESS); 316 317 /* 318 * If something fails in the above loop we were already walking back 319 * up the tree and the tree is now inconsistent. Nothing much we can 320 * do about it but release any memory we're holding. 321 */ 322 err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 323 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 324 325 err2: mpool_put(t->bt_mp, l, 0); 326 mpool_put(t->bt_mp, r, 0); 327 __dbpanic(t->bt_dbp); 328 return (RET_ERROR); 329 } 330 331 /* 332 * BT_PAGE -- Split a non-root page of a btree. 333 * 334 * Parameters: 335 * t: tree 336 * h: root page 337 * lp: pointer to left page pointer 338 * rp: pointer to right page pointer 339 * skip: pointer to index to leave open 340 * ilen: insert length 341 * 342 * Returns: 343 * Pointer to page in which to insert or NULL on error. 344 */ 345 static PAGE * 346 bt_page(t, h, lp, rp, skip, ilen) 347 BTREE *t; 348 PAGE *h, **lp, **rp; 349 indx_t *skip; 350 size_t ilen; 351 { 352 PAGE *l, *r, *tp; 353 db_pgno_t npg; 354 355 #ifdef STATISTICS 356 ++bt_split; 357 #endif 358 /* Put the new right page for the split into place. */ 359 if ((r = __bt_new(t, &npg)) == NULL) 360 return (NULL); 361 r->pgno = npg; 362 r->lower = BTDATAOFF; 363 r->upper = t->bt_psize; 364 r->nextpg = h->nextpg; 365 r->prevpg = h->pgno; 366 r->flags = h->flags & P_TYPE; 367 368 /* 369 * If we're splitting the last page on a level because we're appending 370 * a key to it (skip is NEXTINDEX()), it's likely that the data is 371 * sorted. Adding an empty page on the side of the level is less work 372 * and can push the fill factor much higher than normal. If we're 373 * wrong it's no big deal, we'll just do the split the right way next 374 * time. It may look like it's equally easy to do a similar hack for 375 * reverse sorted data, that is, split the tree left, but it's not. 376 * Don't even try. 377 */ 378 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 379 #ifdef STATISTICS 380 ++bt_sortsplit; 381 #endif 382 h->nextpg = r->pgno; 383 r->lower = BTDATAOFF + sizeof(indx_t); 384 *skip = 0; 385 *lp = h; 386 *rp = r; 387 return (r); 388 } 389 390 /* Put the new left page for the split into place. */ 391 if ((l = (PAGE *)malloc(t->bt_psize)) == NULL) { 392 mpool_put(t->bt_mp, r, 0); 393 return (NULL); 394 } 395 #ifdef PURIFY 396 memset(l, 0xff, t->bt_psize); 397 #endif 398 l->pgno = h->pgno; 399 l->nextpg = r->pgno; 400 l->prevpg = h->prevpg; 401 l->lower = BTDATAOFF; 402 l->upper = t->bt_psize; 403 l->flags = h->flags & P_TYPE; 404 405 /* Fix up the previous pointer of the page after the split page. */ 406 if (h->nextpg != P_INVALID) { 407 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 408 free(l); 409 /* XXX mpool_free(t->bt_mp, r->pgno); */ 410 return (NULL); 411 } 412 tp->prevpg = r->pgno; 413 mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 414 } 415 416 /* 417 * Split right. The key/data pairs aren't sorted in the btree page so 418 * it's simpler to copy the data from the split page onto two new pages 419 * instead of copying half the data to the right page and compacting 420 * the left page in place. Since the left page can't change, we have 421 * to swap the original and the allocated left page after the split. 422 */ 423 tp = bt_psplit(t, h, l, r, skip, ilen); 424 425 /* Move the new left page onto the old left page. */ 426 memmove(h, l, t->bt_psize); 427 if (tp == l) 428 tp = h; 429 free(l); 430 431 *lp = h; 432 *rp = r; 433 return (tp); 434 } 435 436 /* 437 * BT_ROOT -- Split the root page of a btree. 438 * 439 * Parameters: 440 * t: tree 441 * h: root page 442 * lp: pointer to left page pointer 443 * rp: pointer to right page pointer 444 * skip: pointer to index to leave open 445 * ilen: insert length 446 * 447 * Returns: 448 * Pointer to page in which to insert or NULL on error. 449 */ 450 static PAGE * 451 bt_root(t, h, lp, rp, skip, ilen) 452 BTREE *t; 453 PAGE *h, **lp, **rp; 454 indx_t *skip; 455 size_t ilen; 456 { 457 PAGE *l, *r, *tp; 458 db_pgno_t lnpg, rnpg; 459 460 #ifdef STATISTICS 461 ++bt_split; 462 ++bt_rootsplit; 463 #endif 464 /* Put the new left and right pages for the split into place. */ 465 if ((l = __bt_new(t, &lnpg)) == NULL || 466 (r = __bt_new(t, &rnpg)) == NULL) 467 return (NULL); 468 l->pgno = lnpg; 469 r->pgno = rnpg; 470 l->nextpg = r->pgno; 471 r->prevpg = l->pgno; 472 l->prevpg = r->nextpg = P_INVALID; 473 l->lower = r->lower = BTDATAOFF; 474 l->upper = r->upper = t->bt_psize; 475 l->flags = r->flags = h->flags & P_TYPE; 476 477 /* Split the root page. */ 478 tp = bt_psplit(t, h, l, r, skip, ilen); 479 480 *lp = l; 481 *rp = r; 482 return (tp); 483 } 484 485 /* 486 * BT_RROOT -- Fix up the recno root page after it has been split. 487 * 488 * Parameters: 489 * t: tree 490 * h: root page 491 * l: left page 492 * r: right page 493 * 494 * Returns: 495 * RET_ERROR, RET_SUCCESS 496 */ 497 static int 498 bt_rroot(t, h, l, r) 499 BTREE *t; 500 PAGE *h, *l, *r; 501 { 502 char *dest; 503 504 /* Insert the left and right keys, set the header information. */ 505 h->linp[0] = h->upper = t->bt_psize - NRINTERNAL; 506 dest = (char *)h + h->upper; 507 WR_RINTERNAL(dest, 508 l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno); 509 510 h->linp[1] = h->upper -= NRINTERNAL; 511 dest = (char *)h + h->upper; 512 WR_RINTERNAL(dest, 513 r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno); 514 515 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 516 517 /* Unpin the root page, set to recno internal page. */ 518 h->flags &= ~P_TYPE; 519 h->flags |= P_RINTERNAL; 520 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 521 522 return (RET_SUCCESS); 523 } 524 525 /* 526 * BT_BROOT -- Fix up the btree root page after it has been split. 527 * 528 * Parameters: 529 * t: tree 530 * h: root page 531 * l: left page 532 * r: right page 533 * 534 * Returns: 535 * RET_ERROR, RET_SUCCESS 536 */ 537 static int 538 bt_broot(t, h, l, r) 539 BTREE *t; 540 PAGE *h, *l, *r; 541 { 542 BINTERNAL *bi; 543 BLEAF *bl; 544 u_int32_t nbytes; 545 char *dest; 546 547 /* 548 * If the root page was a leaf page, change it into an internal page. 549 * We copy the key we split on (but not the key's data, in the case of 550 * a leaf page) to the new root page. 551 * 552 * The btree comparison code guarantees that the left-most key on any 553 * level of the tree is never used, so it doesn't need to be filled in. 554 */ 555 nbytes = NBINTERNAL(0); 556 h->linp[0] = h->upper = t->bt_psize - nbytes; 557 dest = (char *)h + h->upper; 558 WR_BINTERNAL(dest, 0, l->pgno, 0); 559 560 switch (h->flags & P_TYPE) { 561 case P_BLEAF: 562 bl = GETBLEAF(r, 0); 563 nbytes = NBINTERNAL(bl->ksize); 564 h->linp[1] = h->upper -= nbytes; 565 dest = (char *)h + h->upper; 566 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 567 memmove(dest, bl->bytes, bl->ksize); 568 569 /* 570 * If the key is on an overflow page, mark the overflow chain 571 * so it isn't deleted when the leaf copy of the key is deleted. 572 */ 573 if (bl->flags & P_BIGKEY && 574 bt_preserve(t, *(db_pgno_t *)bl->bytes) == RET_ERROR) 575 return (RET_ERROR); 576 break; 577 case P_BINTERNAL: 578 bi = GETBINTERNAL(r, 0); 579 nbytes = NBINTERNAL(bi->ksize); 580 h->linp[1] = h->upper -= nbytes; 581 dest = (char *)h + h->upper; 582 memmove(dest, bi, nbytes); 583 ((BINTERNAL *)dest)->pgno = r->pgno; 584 break; 585 default: 586 abort(); 587 } 588 589 /* There are two keys on the page. */ 590 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 591 592 /* Unpin the root page, set to btree internal page. */ 593 h->flags &= ~P_TYPE; 594 h->flags |= P_BINTERNAL; 595 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 596 597 return (RET_SUCCESS); 598 } 599 600 /* 601 * BT_PSPLIT -- Do the real work of splitting the page. 602 * 603 * Parameters: 604 * t: tree 605 * h: page to be split 606 * l: page to put lower half of data 607 * r: page to put upper half of data 608 * pskip: pointer to index to leave open 609 * ilen: insert length 610 * 611 * Returns: 612 * Pointer to page in which to insert. 613 */ 614 static PAGE * 615 bt_psplit(t, h, l, r, pskip, ilen) 616 BTREE *t; 617 PAGE *h, *l, *r; 618 indx_t *pskip; 619 size_t ilen; 620 { 621 BINTERNAL *bi; 622 BLEAF *bl; 623 CURSOR *c; 624 RLEAF *rl; 625 PAGE *rval; 626 void *src; 627 indx_t full, half, nxt, off, skip, top, used; 628 u_int32_t nbytes; 629 int bigkeycnt, isbigkey; 630 631 /* 632 * Split the data to the left and right pages. Leave the skip index 633 * open. Additionally, make some effort not to split on an overflow 634 * key. This makes internal page processing faster and can save 635 * space as overflow keys used by internal pages are never deleted. 636 */ 637 bigkeycnt = 0; 638 skip = *pskip; 639 full = t->bt_psize - BTDATAOFF; 640 half = full / 2; 641 used = 0; 642 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 643 if (skip == off) { 644 nbytes = ilen; 645 isbigkey = 0; /* XXX: not really known. */ 646 } else 647 switch (h->flags & P_TYPE) { 648 case P_BINTERNAL: 649 src = bi = GETBINTERNAL(h, nxt); 650 nbytes = NBINTERNAL(bi->ksize); 651 isbigkey = bi->flags & P_BIGKEY; 652 break; 653 case P_BLEAF: 654 src = bl = GETBLEAF(h, nxt); 655 nbytes = NBLEAF(bl); 656 isbigkey = bl->flags & P_BIGKEY; 657 break; 658 case P_RINTERNAL: 659 src = GETRINTERNAL(h, nxt); 660 nbytes = NRINTERNAL; 661 isbigkey = 0; 662 break; 663 case P_RLEAF: 664 src = rl = GETRLEAF(h, nxt); 665 nbytes = NRLEAF(rl); 666 isbigkey = 0; 667 break; 668 default: 669 abort(); 670 } 671 672 /* 673 * If the key/data pairs are substantial fractions of the max 674 * possible size for the page, it's possible to get situations 675 * where we decide to try and copy too much onto the left page. 676 * Make sure that doesn't happen. 677 */ 678 if ((skip <= off && used + nbytes + sizeof(indx_t) >= full) 679 || nxt == top - 1) { 680 --off; 681 break; 682 } 683 684 /* Copy the key/data pair, if not the skipped index. */ 685 if (skip != off) { 686 ++nxt; 687 688 l->linp[off] = l->upper -= nbytes; 689 memmove((char *)l + l->upper, src, nbytes); 690 } 691 692 used += nbytes + sizeof(indx_t); 693 if (used >= half) { 694 if (!isbigkey || bigkeycnt == 3) 695 break; 696 else 697 ++bigkeycnt; 698 } 699 } 700 701 /* 702 * Off is the last offset that's valid for the left page. 703 * Nxt is the first offset to be placed on the right page. 704 */ 705 l->lower += (off + 1) * sizeof(indx_t); 706 707 /* 708 * If splitting the page that the cursor was on, the cursor has to be 709 * adjusted to point to the same record as before the split. If the 710 * cursor is at or past the skipped slot, the cursor is incremented by 711 * one. If the cursor is on the right page, it is decremented by the 712 * number of records split to the left page. 713 */ 714 c = &t->bt_cursor; 715 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 716 if (c->pg.index >= skip) 717 ++c->pg.index; 718 if (c->pg.index < nxt) /* Left page. */ 719 c->pg.pgno = l->pgno; 720 else { /* Right page. */ 721 c->pg.pgno = r->pgno; 722 c->pg.index -= nxt; 723 } 724 } 725 726 /* 727 * If the skipped index was on the left page, just return that page. 728 * Otherwise, adjust the skip index to reflect the new position on 729 * the right page. 730 */ 731 if (skip <= off) { 732 /* 733 * If we get here then 'skip' is in the left page. We do 734 * not want to mix this with the right page, so we assign 735 * an unrealistic value (-1). 736 */ 737 skip = (indx_t)-1; 738 rval = l; 739 } else { 740 rval = r; 741 *pskip -= nxt; 742 } 743 744 for (off = 0; nxt < top; ++off) { 745 if (skip == nxt) { 746 ++off; 747 /* 748 * Assign 'skip' an unrealistic value (-1) to ensure 749 * it is not matched again. 750 */ 751 skip = (indx_t)-1; 752 } 753 switch (h->flags & P_TYPE) { 754 case P_BINTERNAL: 755 src = bi = GETBINTERNAL(h, nxt); 756 nbytes = NBINTERNAL(bi->ksize); 757 break; 758 case P_BLEAF: 759 src = bl = GETBLEAF(h, nxt); 760 nbytes = NBLEAF(bl); 761 break; 762 case P_RINTERNAL: 763 src = GETRINTERNAL(h, nxt); 764 nbytes = NRINTERNAL; 765 break; 766 case P_RLEAF: 767 src = rl = GETRLEAF(h, nxt); 768 nbytes = NRLEAF(rl); 769 break; 770 default: 771 abort(); 772 } 773 ++nxt; 774 r->linp[off] = r->upper -= nbytes; 775 memmove((char *)r + r->upper, src, nbytes); 776 } 777 r->lower += off * sizeof(indx_t); 778 779 /* If the key is being appended to the page, adjust the index. */ 780 if (skip == top) 781 r->lower += sizeof(indx_t); 782 783 return (rval); 784 } 785 786 /* 787 * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 788 * 789 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 790 * record that references them gets deleted. Chains pointed to by internal 791 * pages never get deleted. This routine marks a chain as pointed to by an 792 * internal page. 793 * 794 * Parameters: 795 * t: tree 796 * pg: page number of first page in the chain. 797 * 798 * Returns: 799 * RET_SUCCESS, RET_ERROR. 800 */ 801 static int 802 bt_preserve(t, pg) 803 BTREE *t; 804 db_pgno_t pg; 805 { 806 PAGE *h; 807 808 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 809 return (RET_ERROR); 810 h->flags |= P_PRESERVE; 811 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 812 return (RET_SUCCESS); 813 } 814 815 /* 816 * REC_TOTAL -- Return the number of recno entries below a page. 817 * 818 * Parameters: 819 * h: page 820 * 821 * Returns: 822 * The number of recno entries below a page. 823 * 824 * XXX 825 * These values could be set by the bt_psplit routine. The problem is that the 826 * entry has to be popped off of the stack etc. or the values have to be passed 827 * all the way back to bt_split/bt_rroot and it's not very clean. 828 */ 829 static recno_t 830 rec_total(h) 831 PAGE *h; 832 { 833 recno_t recs; 834 indx_t nxt, top; 835 836 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 837 recs += GETRINTERNAL(h, nxt)->nrecs; 838 return (recs); 839 } 840