1 /* $NetBSD: bt_split.c,v 1.19 2009/04/22 18:44:06 christos Exp $ */ 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if HAVE_NBTOOL_CONFIG_H 36 #include "nbtool_config.h" 37 #endif 38 39 #include <sys/cdefs.h> 40 __RCSID("$NetBSD: bt_split.c,v 1.19 2009/04/22 18:44:06 christos Exp $"); 41 42 #include "namespace.h" 43 #include <sys/types.h> 44 45 #include <assert.h> 46 #include <limits.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 51 #include <db.h> 52 #include "btree.h" 53 54 static int bt_broot(BTREE *, PAGE *, PAGE *, PAGE *); 55 static PAGE *bt_page(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 56 static int bt_preserve(BTREE *, pgno_t); 57 static PAGE *bt_psplit(BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t); 58 static PAGE *bt_root(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 59 static int bt_rroot(BTREE *, PAGE *, PAGE *, PAGE *); 60 static recno_t rec_total(PAGE *); 61 62 #ifdef STATISTICS 63 unsigned long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 64 #endif 65 66 /* 67 * __BT_SPLIT -- Split the tree. 68 * 69 * Parameters: 70 * t: tree 71 * sp: page to split 72 * key: key to insert 73 * data: data to insert 74 * flags: BIGKEY/BIGDATA flags 75 * ilen: insert length 76 * skip: index to leave open 77 * 78 * Returns: 79 * RET_ERROR, RET_SUCCESS 80 */ 81 int 82 __bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags, 83 size_t ilen, uint32_t argskip) 84 { 85 BINTERNAL *bi = NULL; /* pacify gcc */ 86 BLEAF *bl = NULL, *tbl; /* pacify gcc */ 87 DBT a, b; 88 EPGNO *parent; 89 PAGE *h, *l, *r, *lchild, *rchild; 90 indx_t nxtindex; 91 uint16_t skip; 92 uint32_t n, nbytes, nksize = 0; /* pacify gcc */ 93 int parentsplit; 94 char *dest; 95 96 /* 97 * Split the page into two pages, l and r. The split routines return 98 * a pointer to the page into which the key should be inserted and with 99 * skip set to the offset which should be used. Additionally, l and r 100 * are pinned. 101 */ 102 skip = argskip; 103 h = sp->pgno == P_ROOT ? 104 bt_root(t, sp, &l, &r, &skip, ilen) : 105 bt_page(t, sp, &l, &r, &skip, ilen); 106 if (h == NULL) 107 return (RET_ERROR); 108 109 /* 110 * Insert the new key/data pair into the leaf page. (Key inserts 111 * always cause a leaf page to split first.) 112 */ 113 _DBFIT(ilen, indx_t); 114 h->upper -= (indx_t)ilen; 115 h->linp[skip] = h->upper; 116 dest = (char *)(void *)h + h->upper; 117 if (F_ISSET(t, R_RECNO)) 118 WR_RLEAF(dest, data, flags); 119 else 120 WR_BLEAF(dest, key, data, flags); 121 122 /* If the root page was split, make it look right. */ 123 if (sp->pgno == P_ROOT && 124 (F_ISSET(t, R_RECNO) ? 125 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 126 goto err2; 127 128 /* 129 * Now we walk the parent page stack -- a LIFO stack of the pages that 130 * were traversed when we searched for the page that split. Each stack 131 * entry is a page number and a page index offset. The offset is for 132 * the page traversed on the search. We've just split a page, so we 133 * have to insert a new key into the parent page. 134 * 135 * If the insert into the parent page causes it to split, may have to 136 * continue splitting all the way up the tree. We stop if the root 137 * splits or the page inserted into didn't have to split to hold the 138 * new key. Some algorithms replace the key for the old page as well 139 * as the new page. We don't, as there's no reason to believe that the 140 * first key on the old page is any better than the key we have, and, 141 * in the case of a key being placed at index 0 causing the split, the 142 * key is unavailable. 143 * 144 * There are a maximum of 5 pages pinned at any time. We keep the left 145 * and right pages pinned while working on the parent. The 5 are the 146 * two children, left parent and right parent (when the parent splits) 147 * and the root page or the overflow key page when calling bt_preserve. 148 * This code must make sure that all pins are released other than the 149 * root page or overflow page which is unlocked elsewhere. 150 */ 151 while ((parent = BT_POP(t)) != NULL) { 152 lchild = l; 153 rchild = r; 154 155 /* Get the parent page. */ 156 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 157 goto err2; 158 159 /* 160 * The new key goes ONE AFTER the index, because the split 161 * was to the right. 162 */ 163 skip = parent->index + 1; 164 165 /* 166 * Calculate the space needed on the parent page. 167 * 168 * Prefix trees: space hack when inserting into BINTERNAL 169 * pages. Retain only what's needed to distinguish between 170 * the new entry and the LAST entry on the page to its left. 171 * If the keys compare equal, retain the entire key. Note, 172 * we don't touch overflow keys, and the entire key must be 173 * retained for the next-to-left most key on the leftmost 174 * page of each level, or the search will fail. Applicable 175 * ONLY to internal pages that have leaf pages as children. 176 * Further reduction of the key between pairs of internal 177 * pages loses too much information. 178 */ 179 switch (rchild->flags & P_TYPE) { 180 case P_BINTERNAL: 181 bi = GETBINTERNAL(rchild, 0); 182 nbytes = NBINTERNAL(bi->ksize); 183 break; 184 case P_BLEAF: 185 bl = GETBLEAF(rchild, 0); 186 nbytes = NBINTERNAL(bl->ksize); 187 if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 188 (h->prevpg != P_INVALID || skip > 1)) { 189 size_t temp; 190 tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1); 191 a.size = tbl->ksize; 192 a.data = tbl->bytes; 193 b.size = bl->ksize; 194 b.data = bl->bytes; 195 temp = t->bt_pfx(&a, &b); 196 _DBFIT(temp, uint32_t); 197 nksize = (uint32_t)temp; 198 n = NBINTERNAL(nksize); 199 if (n < nbytes) { 200 #ifdef STATISTICS 201 bt_pfxsaved += nbytes - n; 202 #endif 203 nbytes = n; 204 } else 205 nksize = 0; 206 } else 207 nksize = 0; 208 break; 209 case P_RINTERNAL: 210 case P_RLEAF: 211 nbytes = NRINTERNAL; 212 break; 213 default: 214 abort(); 215 } 216 217 /* Split the parent page if necessary or shift the indices. */ 218 if ((uint32_t)h->upper - (uint32_t)h->lower < nbytes + sizeof(indx_t)) { 219 sp = h; 220 h = h->pgno == P_ROOT ? 221 bt_root(t, h, &l, &r, &skip, nbytes) : 222 bt_page(t, h, &l, &r, &skip, nbytes); 223 if (h == NULL) 224 goto err1; 225 parentsplit = 1; 226 } else { 227 if (skip < (nxtindex = NEXTINDEX(h))) 228 memmove(h->linp + skip + 1, h->linp + skip, 229 (nxtindex - skip) * sizeof(indx_t)); 230 h->lower += sizeof(indx_t); 231 parentsplit = 0; 232 } 233 234 /* Insert the key into the parent page. */ 235 switch (rchild->flags & P_TYPE) { 236 case P_BINTERNAL: 237 h->linp[skip] = h->upper -= nbytes; 238 dest = (char *)(void *)h + h->linp[skip]; 239 memmove(dest, bi, nbytes); 240 ((BINTERNAL *)(void *)dest)->pgno = rchild->pgno; 241 break; 242 case P_BLEAF: 243 h->linp[skip] = h->upper -= nbytes; 244 dest = (char *)(void *)h + h->linp[skip]; 245 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 246 rchild->pgno, bl->flags & P_BIGKEY); 247 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 248 if (bl->flags & P_BIGKEY && 249 bt_preserve(t, *(pgno_t *)(void *)bl->bytes) == 250 RET_ERROR) 251 goto err1; 252 break; 253 case P_RINTERNAL: 254 /* 255 * Update the left page count. If split 256 * added at index 0, fix the correct page. 257 */ 258 if (skip > 0) 259 dest = (char *)(void *)h + h->linp[skip - 1]; 260 else 261 dest = (char *)(void *)l + l->linp[NEXTINDEX(l) - 1]; 262 ((RINTERNAL *)(void *)dest)->nrecs = rec_total(lchild); 263 ((RINTERNAL *)(void *)dest)->pgno = lchild->pgno; 264 265 /* Update the right page count. */ 266 h->linp[skip] = h->upper -= nbytes; 267 dest = (char *)(void *)h + h->linp[skip]; 268 ((RINTERNAL *)(void *)dest)->nrecs = rec_total(rchild); 269 ((RINTERNAL *)(void *)dest)->pgno = rchild->pgno; 270 break; 271 case P_RLEAF: 272 /* 273 * Update the left page count. If split 274 * added at index 0, fix the correct page. 275 */ 276 if (skip > 0) 277 dest = (char *)(void *)h + h->linp[skip - 1]; 278 else 279 dest = (char *)(void *)l + l->linp[NEXTINDEX(l) - 1]; 280 ((RINTERNAL *)(void *)dest)->nrecs = NEXTINDEX(lchild); 281 ((RINTERNAL *)(void *)dest)->pgno = lchild->pgno; 282 283 /* Update the right page count. */ 284 h->linp[skip] = h->upper -= nbytes; 285 dest = (char *)(void *)h + h->linp[skip]; 286 ((RINTERNAL *)(void *)dest)->nrecs = NEXTINDEX(rchild); 287 ((RINTERNAL *)(void *)dest)->pgno = rchild->pgno; 288 break; 289 default: 290 abort(); 291 } 292 293 /* Unpin the held pages. */ 294 if (!parentsplit) { 295 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 296 break; 297 } 298 299 /* If the root page was split, make it look right. */ 300 if (sp->pgno == P_ROOT && 301 (F_ISSET(t, R_RECNO) ? 302 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 303 goto err1; 304 305 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 306 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 307 } 308 309 /* Unpin the held pages. */ 310 mpool_put(t->bt_mp, l, MPOOL_DIRTY); 311 mpool_put(t->bt_mp, r, MPOOL_DIRTY); 312 313 /* Clear any pages left on the stack. */ 314 return (RET_SUCCESS); 315 316 /* 317 * If something fails in the above loop we were already walking back 318 * up the tree and the tree is now inconsistent. Nothing much we can 319 * do about it but release any memory we're holding. 320 */ 321 err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 322 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 323 324 err2: mpool_put(t->bt_mp, l, 0); 325 mpool_put(t->bt_mp, r, 0); 326 __dbpanic(t->bt_dbp); 327 return (RET_ERROR); 328 } 329 330 /* 331 * BT_PAGE -- Split a non-root page of a btree. 332 * 333 * Parameters: 334 * t: tree 335 * h: root page 336 * lp: pointer to left page pointer 337 * rp: pointer to right page pointer 338 * skip: pointer to index to leave open 339 * ilen: insert length 340 * 341 * Returns: 342 * Pointer to page in which to insert or NULL on error. 343 */ 344 static PAGE * 345 bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 346 { 347 PAGE *l, *r, *tp; 348 pgno_t npg; 349 350 #ifdef STATISTICS 351 ++bt_split; 352 #endif 353 /* Put the new right page for the split into place. */ 354 if ((r = __bt_new(t, &npg)) == NULL) 355 return (NULL); 356 r->pgno = npg; 357 r->lower = BTDATAOFF; 358 r->upper = t->bt_psize; 359 r->nextpg = h->nextpg; 360 r->prevpg = h->pgno; 361 r->flags = h->flags & P_TYPE; 362 363 /* 364 * If we're splitting the last page on a level because we're appending 365 * a key to it (skip is NEXTINDEX()), it's likely that the data is 366 * sorted. Adding an empty page on the side of the level is less work 367 * and can push the fill factor much higher than normal. If we're 368 * wrong it's no big deal, we'll just do the split the right way next 369 * time. It may look like it's equally easy to do a similar hack for 370 * reverse sorted data, that is, split the tree left, but it's not. 371 * Don't even try. 372 */ 373 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 374 #ifdef STATISTICS 375 ++bt_sortsplit; 376 #endif 377 h->nextpg = r->pgno; 378 r->lower = BTDATAOFF + sizeof(indx_t); 379 *skip = 0; 380 *lp = h; 381 *rp = r; 382 return (r); 383 } 384 385 /* Put the new left page for the split into place. */ 386 if ((l = calloc(1, t->bt_psize)) == NULL) { 387 mpool_put(t->bt_mp, r, 0); 388 return (NULL); 389 } 390 #ifdef PURIFY 391 memset(l, 0xff, t->bt_psize); 392 #endif 393 l->pgno = h->pgno; 394 l->nextpg = r->pgno; 395 l->prevpg = h->prevpg; 396 l->lower = BTDATAOFF; 397 l->upper = t->bt_psize; 398 l->flags = h->flags & P_TYPE; 399 400 /* Fix up the previous pointer of the page after the split page. */ 401 if (h->nextpg != P_INVALID) { 402 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 403 free(l); 404 /* XXX mpool_free(t->bt_mp, r->pgno); */ 405 return (NULL); 406 } 407 tp->prevpg = r->pgno; 408 mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 409 } 410 411 /* 412 * Split right. The key/data pairs aren't sorted in the btree page so 413 * it's simpler to copy the data from the split page onto two new pages 414 * instead of copying half the data to the right page and compacting 415 * the left page in place. Since the left page can't change, we have 416 * to swap the original and the allocated left page after the split. 417 */ 418 tp = bt_psplit(t, h, l, r, skip, ilen); 419 420 /* Move the new left page onto the old left page. */ 421 memmove(h, l, t->bt_psize); 422 if (tp == l) 423 tp = h; 424 free(l); 425 426 *lp = h; 427 *rp = r; 428 return (tp); 429 } 430 431 /* 432 * BT_ROOT -- Split the root page of a btree. 433 * 434 * Parameters: 435 * t: tree 436 * h: root page 437 * lp: pointer to left page pointer 438 * rp: pointer to right page pointer 439 * skip: pointer to index to leave open 440 * ilen: insert length 441 * 442 * Returns: 443 * Pointer to page in which to insert or NULL on error. 444 */ 445 static PAGE * 446 bt_root(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 447 { 448 PAGE *l, *r, *tp; 449 pgno_t lnpg, rnpg; 450 451 #ifdef STATISTICS 452 ++bt_split; 453 ++bt_rootsplit; 454 #endif 455 /* Put the new left and right pages for the split into place. */ 456 if ((l = __bt_new(t, &lnpg)) == NULL || 457 (r = __bt_new(t, &rnpg)) == NULL) 458 return (NULL); 459 l->pgno = lnpg; 460 r->pgno = rnpg; 461 l->nextpg = r->pgno; 462 r->prevpg = l->pgno; 463 l->prevpg = r->nextpg = P_INVALID; 464 l->lower = r->lower = BTDATAOFF; 465 l->upper = r->upper = t->bt_psize; 466 l->flags = r->flags = h->flags & P_TYPE; 467 468 /* Split the root page. */ 469 tp = bt_psplit(t, h, l, r, skip, ilen); 470 471 *lp = l; 472 *rp = r; 473 return (tp); 474 } 475 476 /* 477 * BT_RROOT -- Fix up the recno root page after it has been split. 478 * 479 * Parameters: 480 * t: tree 481 * h: root page 482 * l: left page 483 * r: right page 484 * 485 * Returns: 486 * RET_ERROR, RET_SUCCESS 487 */ 488 static int 489 bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 490 { 491 char *dest; 492 uint32_t sz; 493 size_t temp; 494 495 temp = t->bt_psize - NRINTERNAL; 496 _DBFIT(temp, uint32_t); 497 sz = (uint32_t)temp; 498 499 /* Insert the left and right keys, set the header information. */ 500 _DBFIT(sz, indx_t); 501 h->linp[0] = h->upper = (indx_t)sz; 502 dest = (char *)(void *)h + h->upper; 503 WR_RINTERNAL(dest, 504 l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno); 505 506 h->linp[1] = h->upper -= NRINTERNAL; 507 dest = (char *)(void *)h + h->upper; 508 WR_RINTERNAL(dest, 509 r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno); 510 511 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 512 513 /* Unpin the root page, set to recno internal page. */ 514 h->flags &= ~P_TYPE; 515 h->flags |= P_RINTERNAL; 516 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 517 518 return (RET_SUCCESS); 519 } 520 521 /* 522 * BT_BROOT -- Fix up the btree root page after it has been split. 523 * 524 * Parameters: 525 * t: tree 526 * h: root page 527 * l: left page 528 * r: right page 529 * 530 * Returns: 531 * RET_ERROR, RET_SUCCESS 532 */ 533 static int 534 bt_broot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 535 { 536 BINTERNAL *bi = NULL; /* pacify gcc */ 537 BLEAF *bl; 538 uint32_t nbytes; 539 char *dest; 540 541 /* 542 * If the root page was a leaf page, change it into an internal page. 543 * We copy the key we split on (but not the key's data, in the case of 544 * a leaf page) to the new root page. 545 * 546 * The btree comparison code guarantees that the left-most key on any 547 * level of the tree is never used, so it doesn't need to be filled in. 548 */ 549 nbytes = NBINTERNAL(0); 550 h->linp[0] = h->upper = t->bt_psize - nbytes; 551 dest = (char *)(void *)h + h->upper; 552 WR_BINTERNAL(dest, 0, l->pgno, 0); 553 554 switch (h->flags & P_TYPE) { 555 case P_BLEAF: 556 bl = GETBLEAF(r, 0); 557 nbytes = NBINTERNAL(bl->ksize); 558 h->linp[1] = h->upper -= nbytes; 559 dest = (char *)(void *)h + h->upper; 560 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 561 memmove(dest, bl->bytes, bl->ksize); 562 563 /* 564 * If the key is on an overflow page, mark the overflow chain 565 * so it isn't deleted when the leaf copy of the key is deleted. 566 */ 567 if (bl->flags & P_BIGKEY && 568 bt_preserve(t, *(pgno_t *)(void *)bl->bytes) == RET_ERROR) 569 return (RET_ERROR); 570 break; 571 case P_BINTERNAL: 572 bi = GETBINTERNAL(r, 0); 573 nbytes = NBINTERNAL(bi->ksize); 574 h->linp[1] = h->upper -= nbytes; 575 dest = (char *)(void *)h + h->upper; 576 memmove(dest, bi, nbytes); 577 ((BINTERNAL *)(void *)dest)->pgno = r->pgno; 578 break; 579 default: 580 abort(); 581 } 582 583 /* There are two keys on the page. */ 584 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 585 586 /* Unpin the root page, set to btree internal page. */ 587 h->flags &= ~P_TYPE; 588 h->flags |= P_BINTERNAL; 589 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 590 591 return (RET_SUCCESS); 592 } 593 594 /* 595 * BT_PSPLIT -- Do the real work of splitting the page. 596 * 597 * Parameters: 598 * t: tree 599 * h: page to be split 600 * l: page to put lower half of data 601 * r: page to put upper half of data 602 * pskip: pointer to index to leave open 603 * ilen: insert length 604 * 605 * Returns: 606 * Pointer to page in which to insert. 607 */ 608 static PAGE * 609 bt_psplit(BTREE *t, PAGE *h, PAGE *l, PAGE *r, indx_t *pskip, size_t ilen) 610 { 611 BINTERNAL *bi; 612 BLEAF *bl; 613 CURSOR *c; 614 RLEAF *rl; 615 PAGE *rval; 616 void *src = NULL; /* pacify gcc */ 617 indx_t full, half, nxt, off, skip, top, used; 618 uint32_t nbytes; 619 size_t temp; 620 int bigkeycnt, isbigkey; 621 622 /* 623 * Split the data to the left and right pages. Leave the skip index 624 * open. Additionally, make some effort not to split on an overflow 625 * key. This makes internal page processing faster and can save 626 * space as overflow keys used by internal pages are never deleted. 627 */ 628 bigkeycnt = 0; 629 skip = *pskip; 630 temp = t->bt_psize - BTDATAOFF; 631 _DBFIT(temp, indx_t); 632 full = (indx_t)temp; 633 half = full / 2; 634 used = 0; 635 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 636 if (skip == off) { 637 _DBFIT(ilen, uint32_t); 638 nbytes = (uint32_t)ilen; 639 isbigkey = 0; /* XXX: not really known. */ 640 } else 641 switch (h->flags & P_TYPE) { 642 case P_BINTERNAL: 643 src = bi = GETBINTERNAL(h, nxt); 644 nbytes = NBINTERNAL(bi->ksize); 645 isbigkey = bi->flags & P_BIGKEY; 646 break; 647 case P_BLEAF: 648 src = bl = GETBLEAF(h, nxt); 649 nbytes = NBLEAF(bl); 650 isbigkey = bl->flags & P_BIGKEY; 651 break; 652 case P_RINTERNAL: 653 src = GETRINTERNAL(h, nxt); 654 nbytes = NRINTERNAL; 655 isbigkey = 0; 656 break; 657 case P_RLEAF: 658 src = rl = GETRLEAF(h, nxt); 659 nbytes = NRLEAF(rl); 660 isbigkey = 0; 661 break; 662 default: 663 abort(); 664 } 665 666 /* 667 * If the key/data pairs are substantial fractions of the max 668 * possible size for the page, it's possible to get situations 669 * where we decide to try and copy too much onto the left page. 670 * Make sure that doesn't happen. 671 */ 672 if ((skip <= off && used + nbytes + sizeof(indx_t) >= full) || 673 nxt == top - 1) { 674 --off; 675 break; 676 } 677 678 /* Copy the key/data pair, if not the skipped index. */ 679 if (skip != off) { 680 ++nxt; 681 682 l->linp[off] = l->upper -= nbytes; 683 memmove((char *)(void *)l + l->upper, src, nbytes); 684 } 685 686 temp = nbytes + sizeof(indx_t); 687 _DBFIT(temp, indx_t); 688 used += (indx_t)temp; 689 if (used >= half) { 690 if (!isbigkey || bigkeycnt == 3) 691 break; 692 else 693 ++bigkeycnt; 694 } 695 } 696 697 /* 698 * Off is the last offset that's valid for the left page. 699 * Nxt is the first offset to be placed on the right page. 700 */ 701 temp = (off + 1) * sizeof(indx_t); 702 _DBFIT(temp, indx_t); 703 l->lower += (indx_t)temp; 704 705 /* 706 * If splitting the page that the cursor was on, the cursor has to be 707 * adjusted to point to the same record as before the split. If the 708 * cursor is at or past the skipped slot, the cursor is incremented by 709 * one. If the cursor is on the right page, it is decremented by the 710 * number of records split to the left page. 711 */ 712 c = &t->bt_cursor; 713 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 714 if (c->pg.index >= skip) 715 ++c->pg.index; 716 if (c->pg.index < nxt) /* Left page. */ 717 c->pg.pgno = l->pgno; 718 else { /* Right page. */ 719 c->pg.pgno = r->pgno; 720 c->pg.index -= nxt; 721 } 722 } 723 724 /* 725 * If the skipped index was on the left page, just return that page. 726 * Otherwise, adjust the skip index to reflect the new position on 727 * the right page. 728 */ 729 if (skip <= off) { 730 skip = MAX_PAGE_OFFSET; 731 rval = l; 732 } else { 733 rval = r; 734 *pskip -= nxt; 735 } 736 737 for (off = 0; nxt < top; ++off) { 738 if (skip == nxt) { 739 ++off; 740 skip = MAX_PAGE_OFFSET; 741 } 742 switch (h->flags & P_TYPE) { 743 case P_BINTERNAL: 744 src = bi = GETBINTERNAL(h, nxt); 745 nbytes = NBINTERNAL(bi->ksize); 746 break; 747 case P_BLEAF: 748 src = bl = GETBLEAF(h, nxt); 749 nbytes = NBLEAF(bl); 750 break; 751 case P_RINTERNAL: 752 src = GETRINTERNAL(h, nxt); 753 nbytes = NRINTERNAL; 754 break; 755 case P_RLEAF: 756 src = rl = GETRLEAF(h, nxt); 757 nbytes = NRLEAF(rl); 758 break; 759 default: 760 abort(); 761 } 762 ++nxt; 763 r->linp[off] = r->upper -= nbytes; 764 memmove((char *)(void *)r + r->upper, src, nbytes); 765 } 766 temp = off * sizeof(indx_t); 767 _DBFIT(temp, indx_t); 768 r->lower += (indx_t)temp; 769 770 /* If the key is being appended to the page, adjust the index. */ 771 if (skip == top) 772 r->lower += sizeof(indx_t); 773 774 return (rval); 775 } 776 777 /* 778 * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 779 * 780 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 781 * record that references them gets deleted. Chains pointed to by internal 782 * pages never get deleted. This routine marks a chain as pointed to by an 783 * internal page. 784 * 785 * Parameters: 786 * t: tree 787 * pg: page number of first page in the chain. 788 * 789 * Returns: 790 * RET_SUCCESS, RET_ERROR. 791 */ 792 static int 793 bt_preserve(BTREE *t, pgno_t pg) 794 { 795 PAGE *h; 796 797 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 798 return (RET_ERROR); 799 h->flags |= P_PRESERVE; 800 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 801 return (RET_SUCCESS); 802 } 803 804 /* 805 * REC_TOTAL -- Return the number of recno entries below a page. 806 * 807 * Parameters: 808 * h: page 809 * 810 * Returns: 811 * The number of recno entries below a page. 812 * 813 * XXX 814 * These values could be set by the bt_psplit routine. The problem is that the 815 * entry has to be popped off of the stack etc. or the values have to be passed 816 * all the way back to bt_split/bt_rroot and it's not very clean. 817 */ 818 static recno_t 819 rec_total(PAGE *h) 820 { 821 recno_t recs; 822 indx_t nxt, top; 823 824 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 825 recs += GETRINTERNAL(h, nxt)->nrecs; 826 return (recs); 827 } 828