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 #ifndef __minix 41 __RCSID("$NetBSD: bt_split.c,v 1.19 2009/04/22 18:44:06 christos Exp $"); 42 #endif 43 44 #ifndef __minix 45 #include "namespace.h" 46 #endif 47 #include <sys/types.h> 48 49 #include <assert.h> 50 #include <limits.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 55 #include <db.h> 56 #include "btree.h" 57 58 static int bt_broot(BTREE *, PAGE *, PAGE *, PAGE *); 59 static PAGE *bt_page(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 60 static int bt_preserve(BTREE *, pgno_t); 61 static PAGE *bt_psplit(BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t); 62 static PAGE *bt_root(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t); 63 static int bt_rroot(BTREE *, PAGE *, PAGE *, PAGE *); 64 static recno_t rec_total(PAGE *); 65 66 #ifdef STATISTICS 67 unsigned long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 68 #endif 69 70 /* 71 * __BT_SPLIT -- Split the tree. 72 * 73 * Parameters: 74 * t: tree 75 * sp: page to split 76 * key: key to insert 77 * data: data to insert 78 * flags: BIGKEY/BIGDATA flags 79 * ilen: insert length 80 * skip: index to leave open 81 * 82 * Returns: 83 * RET_ERROR, RET_SUCCESS 84 */ 85 int 86 __bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags, 87 size_t ilen, uint32_t argskip) 88 { 89 BINTERNAL *bi = NULL; /* pacify gcc */ 90 BLEAF *bl = NULL, *tbl; /* pacify gcc */ 91 DBT a, b; 92 EPGNO *parent; 93 PAGE *h, *l, *r, *lchild, *rchild; 94 indx_t nxtindex; 95 uint16_t skip; 96 uint32_t n, nbytes, nksize = 0; /* pacify gcc */ 97 int parentsplit; 98 char *dest; 99 100 /* 101 * Split the page into two pages, l and r. The split routines return 102 * a pointer to the page into which the key should be inserted and with 103 * skip set to the offset which should be used. Additionally, l and r 104 * are pinned. 105 */ 106 skip = argskip; 107 h = sp->pgno == P_ROOT ? 108 bt_root(t, sp, &l, &r, &skip, ilen) : 109 bt_page(t, sp, &l, &r, &skip, ilen); 110 if (h == NULL) 111 return (RET_ERROR); 112 113 /* 114 * Insert the new key/data pair into the leaf page. (Key inserts 115 * always cause a leaf page to split first.) 116 */ 117 _DBFIT(ilen, indx_t); 118 h->upper -= (indx_t)ilen; 119 h->linp[skip] = h->upper; 120 dest = (char *)(void *)h + h->upper; 121 if (F_ISSET(t, R_RECNO)) 122 WR_RLEAF(dest, data, flags); 123 else 124 WR_BLEAF(dest, key, data, flags); 125 126 /* If the root page was split, make it look right. */ 127 if (sp->pgno == P_ROOT && 128 (F_ISSET(t, R_RECNO) ? 129 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 130 goto err2; 131 132 /* 133 * Now we walk the parent page stack -- a LIFO stack of the pages that 134 * were traversed when we searched for the page that split. Each stack 135 * entry is a page number and a page index offset. The offset is for 136 * the page traversed on the search. We've just split a page, so we 137 * have to insert a new key into the parent page. 138 * 139 * If the insert into the parent page causes it to split, may have to 140 * continue splitting all the way up the tree. We stop if the root 141 * splits or the page inserted into didn't have to split to hold the 142 * new key. Some algorithms replace the key for the old page as well 143 * as the new page. We don't, as there's no reason to believe that the 144 * first key on the old page is any better than the key we have, and, 145 * in the case of a key being placed at index 0 causing the split, the 146 * key is unavailable. 147 * 148 * There are a maximum of 5 pages pinned at any time. We keep the left 149 * and right pages pinned while working on the parent. The 5 are the 150 * two children, left parent and right parent (when the parent splits) 151 * and the root page or the overflow key page when calling bt_preserve. 152 * This code must make sure that all pins are released other than the 153 * root page or overflow page which is unlocked elsewhere. 154 */ 155 while ((parent = BT_POP(t)) != NULL) { 156 lchild = l; 157 rchild = r; 158 159 /* Get the parent page. */ 160 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 161 goto err2; 162 163 /* 164 * The new key goes ONE AFTER the index, because the split 165 * was to the right. 166 */ 167 skip = parent->index + 1; 168 169 /* 170 * Calculate the space needed on the parent page. 171 * 172 * Prefix trees: space hack when inserting into BINTERNAL 173 * pages. Retain only what's needed to distinguish between 174 * the new entry and the LAST entry on the page to its left. 175 * If the keys compare equal, retain the entire key. Note, 176 * we don't touch overflow keys, and the entire key must be 177 * retained for the next-to-left most key on the leftmost 178 * page of each level, or the search will fail. Applicable 179 * ONLY to internal pages that have leaf pages as children. 180 * Further reduction of the key between pairs of internal 181 * pages loses too much information. 182 */ 183 switch (rchild->flags & P_TYPE) { 184 case P_BINTERNAL: 185 bi = GETBINTERNAL(rchild, 0); 186 nbytes = NBINTERNAL(bi->ksize); 187 break; 188 case P_BLEAF: 189 bl = GETBLEAF(rchild, 0); 190 nbytes = NBINTERNAL(bl->ksize); 191 if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 192 (h->prevpg != P_INVALID || skip > 1)) { 193 size_t temp; 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 temp = t->bt_pfx(&a, &b); 200 _DBFIT(temp, uint32_t); 201 nksize = (uint32_t)temp; 202 n = NBINTERNAL(nksize); 203 if (n < nbytes) { 204 #ifdef STATISTICS 205 bt_pfxsaved += nbytes - n; 206 #endif 207 nbytes = n; 208 } else 209 nksize = 0; 210 } else 211 nksize = 0; 212 break; 213 case P_RINTERNAL: 214 case P_RLEAF: 215 nbytes = NRINTERNAL; 216 break; 217 default: 218 abort(); 219 } 220 221 /* Split the parent page if necessary or shift the indices. */ 222 if ((uint32_t)h->upper - (uint32_t)h->lower < nbytes + sizeof(indx_t)) { 223 sp = h; 224 h = h->pgno == P_ROOT ? 225 bt_root(t, h, &l, &r, &skip, nbytes) : 226 bt_page(t, h, &l, &r, &skip, nbytes); 227 if (h == NULL) 228 goto err1; 229 parentsplit = 1; 230 } else { 231 if (skip < (nxtindex = NEXTINDEX(h))) 232 memmove(h->linp + skip + 1, h->linp + skip, 233 (nxtindex - skip) * sizeof(indx_t)); 234 h->lower += sizeof(indx_t); 235 parentsplit = 0; 236 } 237 238 /* Insert the key into the parent page. */ 239 switch (rchild->flags & P_TYPE) { 240 case P_BINTERNAL: 241 h->linp[skip] = h->upper -= nbytes; 242 dest = (char *)(void *)h + h->linp[skip]; 243 memmove(dest, bi, nbytes); 244 ((BINTERNAL *)(void *)dest)->pgno = rchild->pgno; 245 break; 246 case P_BLEAF: 247 h->linp[skip] = h->upper -= nbytes; 248 dest = (char *)(void *)h + h->linp[skip]; 249 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 250 rchild->pgno, bl->flags & P_BIGKEY); 251 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 252 if (bl->flags & P_BIGKEY && 253 bt_preserve(t, *(pgno_t *)(void *)bl->bytes) == 254 RET_ERROR) 255 goto err1; 256 break; 257 case P_RINTERNAL: 258 /* 259 * Update the left page count. If split 260 * added at index 0, fix the correct page. 261 */ 262 if (skip > 0) 263 dest = (char *)(void *)h + h->linp[skip - 1]; 264 else 265 dest = (char *)(void *)l + l->linp[NEXTINDEX(l) - 1]; 266 ((RINTERNAL *)(void *)dest)->nrecs = rec_total(lchild); 267 ((RINTERNAL *)(void *)dest)->pgno = lchild->pgno; 268 269 /* Update the right page count. */ 270 h->linp[skip] = h->upper -= nbytes; 271 dest = (char *)(void *)h + h->linp[skip]; 272 ((RINTERNAL *)(void *)dest)->nrecs = rec_total(rchild); 273 ((RINTERNAL *)(void *)dest)->pgno = rchild->pgno; 274 break; 275 case P_RLEAF: 276 /* 277 * Update the left page count. If split 278 * added at index 0, fix the correct page. 279 */ 280 if (skip > 0) 281 dest = (char *)(void *)h + h->linp[skip - 1]; 282 else 283 dest = (char *)(void *)l + l->linp[NEXTINDEX(l) - 1]; 284 ((RINTERNAL *)(void *)dest)->nrecs = NEXTINDEX(lchild); 285 ((RINTERNAL *)(void *)dest)->pgno = lchild->pgno; 286 287 /* Update the right page count. */ 288 h->linp[skip] = h->upper -= nbytes; 289 dest = (char *)(void *)h + h->linp[skip]; 290 ((RINTERNAL *)(void *)dest)->nrecs = NEXTINDEX(rchild); 291 ((RINTERNAL *)(void *)dest)->pgno = rchild->pgno; 292 break; 293 default: 294 abort(); 295 } 296 297 /* Unpin the held pages. */ 298 if (!parentsplit) { 299 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 300 break; 301 } 302 303 /* If the root page was split, make it look right. */ 304 if (sp->pgno == P_ROOT && 305 (F_ISSET(t, R_RECNO) ? 306 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 307 goto err1; 308 309 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 310 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 311 } 312 313 /* Unpin the held pages. */ 314 mpool_put(t->bt_mp, l, MPOOL_DIRTY); 315 mpool_put(t->bt_mp, r, MPOOL_DIRTY); 316 317 /* Clear any pages left on the stack. */ 318 return (RET_SUCCESS); 319 320 /* 321 * If something fails in the above loop we were already walking back 322 * up the tree and the tree is now inconsistent. Nothing much we can 323 * do about it but release any memory we're holding. 324 */ 325 err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 326 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 327 328 err2: mpool_put(t->bt_mp, l, 0); 329 mpool_put(t->bt_mp, r, 0); 330 __dbpanic(t->bt_dbp); 331 return (RET_ERROR); 332 } 333 334 /* 335 * BT_PAGE -- Split a non-root page of a btree. 336 * 337 * Parameters: 338 * t: tree 339 * h: root page 340 * lp: pointer to left page pointer 341 * rp: pointer to right page pointer 342 * skip: pointer to index to leave open 343 * ilen: insert length 344 * 345 * Returns: 346 * Pointer to page in which to insert or NULL on error. 347 */ 348 static PAGE * 349 bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 350 { 351 PAGE *l, *r, *tp; 352 pgno_t npg; 353 354 #ifdef STATISTICS 355 ++bt_split; 356 #endif 357 /* Put the new right page for the split into place. */ 358 if ((r = __bt_new(t, &npg)) == NULL) 359 return (NULL); 360 r->pgno = npg; 361 r->lower = BTDATAOFF; 362 r->upper = t->bt_psize; 363 r->nextpg = h->nextpg; 364 r->prevpg = h->pgno; 365 r->flags = h->flags & P_TYPE; 366 367 /* 368 * If we're splitting the last page on a level because we're appending 369 * a key to it (skip is NEXTINDEX()), it's likely that the data is 370 * sorted. Adding an empty page on the side of the level is less work 371 * and can push the fill factor much higher than normal. If we're 372 * wrong it's no big deal, we'll just do the split the right way next 373 * time. It may look like it's equally easy to do a similar hack for 374 * reverse sorted data, that is, split the tree left, but it's not. 375 * Don't even try. 376 */ 377 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 378 #ifdef STATISTICS 379 ++bt_sortsplit; 380 #endif 381 h->nextpg = r->pgno; 382 r->lower = BTDATAOFF + sizeof(indx_t); 383 *skip = 0; 384 *lp = h; 385 *rp = r; 386 return (r); 387 } 388 389 /* Put the new left page for the split into place. */ 390 if ((l = calloc(1, t->bt_psize)) == NULL) { 391 mpool_put(t->bt_mp, r, 0); 392 return (NULL); 393 } 394 #ifdef PURIFY 395 memset(l, 0xff, t->bt_psize); 396 #endif 397 l->pgno = h->pgno; 398 l->nextpg = r->pgno; 399 l->prevpg = h->prevpg; 400 l->lower = BTDATAOFF; 401 l->upper = t->bt_psize; 402 l->flags = h->flags & P_TYPE; 403 404 /* Fix up the previous pointer of the page after the split page. */ 405 if (h->nextpg != P_INVALID) { 406 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 407 free(l); 408 /* XXX mpool_free(t->bt_mp, r->pgno); */ 409 return (NULL); 410 } 411 tp->prevpg = r->pgno; 412 mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 413 } 414 415 /* 416 * Split right. The key/data pairs aren't sorted in the btree page so 417 * it's simpler to copy the data from the split page onto two new pages 418 * instead of copying half the data to the right page and compacting 419 * the left page in place. Since the left page can't change, we have 420 * to swap the original and the allocated left page after the split. 421 */ 422 tp = bt_psplit(t, h, l, r, skip, ilen); 423 424 /* Move the new left page onto the old left page. */ 425 memmove(h, l, t->bt_psize); 426 if (tp == l) 427 tp = h; 428 free(l); 429 430 *lp = h; 431 *rp = r; 432 return (tp); 433 } 434 435 /* 436 * BT_ROOT -- Split the root page of a btree. 437 * 438 * Parameters: 439 * t: tree 440 * h: root page 441 * lp: pointer to left page pointer 442 * rp: pointer to right page pointer 443 * skip: pointer to index to leave open 444 * ilen: insert length 445 * 446 * Returns: 447 * Pointer to page in which to insert or NULL on error. 448 */ 449 static PAGE * 450 bt_root(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen) 451 { 452 PAGE *l, *r, *tp; 453 pgno_t lnpg, rnpg; 454 455 #ifdef STATISTICS 456 ++bt_split; 457 ++bt_rootsplit; 458 #endif 459 /* Put the new left and right pages for the split into place. */ 460 if ((l = __bt_new(t, &lnpg)) == NULL || 461 (r = __bt_new(t, &rnpg)) == NULL) 462 return (NULL); 463 l->pgno = lnpg; 464 r->pgno = rnpg; 465 l->nextpg = r->pgno; 466 r->prevpg = l->pgno; 467 l->prevpg = r->nextpg = P_INVALID; 468 l->lower = r->lower = BTDATAOFF; 469 l->upper = r->upper = t->bt_psize; 470 l->flags = r->flags = h->flags & P_TYPE; 471 472 /* Split the root page. */ 473 tp = bt_psplit(t, h, l, r, skip, ilen); 474 475 *lp = l; 476 *rp = r; 477 return (tp); 478 } 479 480 /* 481 * BT_RROOT -- Fix up the recno root page after it has been split. 482 * 483 * Parameters: 484 * t: tree 485 * h: root page 486 * l: left page 487 * r: right page 488 * 489 * Returns: 490 * RET_ERROR, RET_SUCCESS 491 */ 492 static int 493 bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 494 { 495 char *dest; 496 uint32_t sz; 497 size_t temp; 498 499 temp = t->bt_psize - NRINTERNAL; 500 _DBFIT(temp, uint32_t); 501 sz = (uint32_t)temp; 502 503 /* Insert the left and right keys, set the header information. */ 504 _DBFIT(sz, indx_t); 505 h->linp[0] = h->upper = (indx_t)sz; 506 dest = (char *)(void *)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 *)(void *)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(BTREE *t, PAGE *h, PAGE *l, PAGE *r) 539 { 540 BINTERNAL *bi = NULL; /* pacify gcc */ 541 BLEAF *bl; 542 uint32_t nbytes; 543 char *dest; 544 545 /* 546 * If the root page was a leaf page, change it into an internal page. 547 * We copy the key we split on (but not the key's data, in the case of 548 * a leaf page) to the new root page. 549 * 550 * The btree comparison code guarantees that the left-most key on any 551 * level of the tree is never used, so it doesn't need to be filled in. 552 */ 553 nbytes = NBINTERNAL(0); 554 h->linp[0] = h->upper = t->bt_psize - nbytes; 555 dest = (char *)(void *)h + h->upper; 556 WR_BINTERNAL(dest, 0, l->pgno, 0); 557 558 switch (h->flags & P_TYPE) { 559 case P_BLEAF: 560 bl = GETBLEAF(r, 0); 561 nbytes = NBINTERNAL(bl->ksize); 562 h->linp[1] = h->upper -= nbytes; 563 dest = (char *)(void *)h + h->upper; 564 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 565 memmove(dest, bl->bytes, bl->ksize); 566 567 /* 568 * If the key is on an overflow page, mark the overflow chain 569 * so it isn't deleted when the leaf copy of the key is deleted. 570 */ 571 if (bl->flags & P_BIGKEY && 572 bt_preserve(t, *(pgno_t *)(void *)bl->bytes) == RET_ERROR) 573 return (RET_ERROR); 574 break; 575 case P_BINTERNAL: 576 bi = GETBINTERNAL(r, 0); 577 nbytes = NBINTERNAL(bi->ksize); 578 h->linp[1] = h->upper -= nbytes; 579 dest = (char *)(void *)h + h->upper; 580 memmove(dest, bi, nbytes); 581 ((BINTERNAL *)(void *)dest)->pgno = r->pgno; 582 break; 583 default: 584 abort(); 585 } 586 587 /* There are two keys on the page. */ 588 h->lower = BTDATAOFF + 2 * sizeof(indx_t); 589 590 /* Unpin the root page, set to btree internal page. */ 591 h->flags &= ~P_TYPE; 592 h->flags |= P_BINTERNAL; 593 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 594 595 return (RET_SUCCESS); 596 } 597 598 /* 599 * BT_PSPLIT -- Do the real work of splitting the page. 600 * 601 * Parameters: 602 * t: tree 603 * h: page to be split 604 * l: page to put lower half of data 605 * r: page to put upper half of data 606 * pskip: pointer to index to leave open 607 * ilen: insert length 608 * 609 * Returns: 610 * Pointer to page in which to insert. 611 */ 612 static PAGE * 613 bt_psplit(BTREE *t, PAGE *h, PAGE *l, PAGE *r, indx_t *pskip, size_t ilen) 614 { 615 BINTERNAL *bi; 616 BLEAF *bl; 617 CURSOR *c; 618 RLEAF *rl; 619 PAGE *rval; 620 void *src = NULL; /* pacify gcc */ 621 indx_t full, half, nxt, off, skip, top, used; 622 uint32_t nbytes; 623 size_t temp; 624 int bigkeycnt, isbigkey; 625 626 /* 627 * Split the data to the left and right pages. Leave the skip index 628 * open. Additionally, make some effort not to split on an overflow 629 * key. This makes internal page processing faster and can save 630 * space as overflow keys used by internal pages are never deleted. 631 */ 632 bigkeycnt = 0; 633 skip = *pskip; 634 temp = t->bt_psize - BTDATAOFF; 635 _DBFIT(temp, indx_t); 636 full = (indx_t)temp; 637 half = full / 2; 638 used = 0; 639 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 640 if (skip == off) { 641 _DBFIT(ilen, uint32_t); 642 nbytes = (uint32_t)ilen; 643 isbigkey = 0; /* XXX: not really known. */ 644 } else 645 switch (h->flags & P_TYPE) { 646 case P_BINTERNAL: 647 src = bi = GETBINTERNAL(h, nxt); 648 nbytes = NBINTERNAL(bi->ksize); 649 isbigkey = bi->flags & P_BIGKEY; 650 break; 651 case P_BLEAF: 652 src = bl = GETBLEAF(h, nxt); 653 nbytes = NBLEAF(bl); 654 isbigkey = bl->flags & P_BIGKEY; 655 break; 656 case P_RINTERNAL: 657 src = GETRINTERNAL(h, nxt); 658 nbytes = NRINTERNAL; 659 isbigkey = 0; 660 break; 661 case P_RLEAF: 662 src = rl = GETRLEAF(h, nxt); 663 nbytes = NRLEAF(rl); 664 isbigkey = 0; 665 break; 666 default: 667 abort(); 668 } 669 670 /* 671 * If the key/data pairs are substantial fractions of the max 672 * possible size for the page, it's possible to get situations 673 * where we decide to try and copy too much onto the left page. 674 * Make sure that doesn't happen. 675 */ 676 if ((skip <= off && used + nbytes + sizeof(indx_t) >= full) || 677 nxt == top - 1) { 678 --off; 679 break; 680 } 681 682 /* Copy the key/data pair, if not the skipped index. */ 683 if (skip != off) { 684 ++nxt; 685 686 l->linp[off] = l->upper -= nbytes; 687 memmove((char *)(void *)l + l->upper, src, nbytes); 688 } 689 690 temp = nbytes + sizeof(indx_t); 691 _DBFIT(temp, indx_t); 692 used += (indx_t)temp; 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 temp = (off + 1) * sizeof(indx_t); 706 _DBFIT(temp, indx_t); 707 l->lower += (indx_t)temp; 708 709 /* 710 * If splitting the page that the cursor was on, the cursor has to be 711 * adjusted to point to the same record as before the split. If the 712 * cursor is at or past the skipped slot, the cursor is incremented by 713 * one. If the cursor is on the right page, it is decremented by the 714 * number of records split to the left page. 715 */ 716 c = &t->bt_cursor; 717 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 718 if (c->pg.index >= skip) 719 ++c->pg.index; 720 if (c->pg.index < nxt) /* Left page. */ 721 c->pg.pgno = l->pgno; 722 else { /* Right page. */ 723 c->pg.pgno = r->pgno; 724 c->pg.index -= nxt; 725 } 726 } 727 728 /* 729 * If the skipped index was on the left page, just return that page. 730 * Otherwise, adjust the skip index to reflect the new position on 731 * the right page. 732 */ 733 if (skip <= off) { 734 skip = MAX_PAGE_OFFSET; 735 rval = l; 736 } else { 737 rval = r; 738 *pskip -= nxt; 739 } 740 741 for (off = 0; nxt < top; ++off) { 742 if (skip == nxt) { 743 ++off; 744 skip = MAX_PAGE_OFFSET; 745 } 746 switch (h->flags & P_TYPE) { 747 case P_BINTERNAL: 748 src = bi = GETBINTERNAL(h, nxt); 749 nbytes = NBINTERNAL(bi->ksize); 750 break; 751 case P_BLEAF: 752 src = bl = GETBLEAF(h, nxt); 753 nbytes = NBLEAF(bl); 754 break; 755 case P_RINTERNAL: 756 src = GETRINTERNAL(h, nxt); 757 nbytes = NRINTERNAL; 758 break; 759 case P_RLEAF: 760 src = rl = GETRLEAF(h, nxt); 761 nbytes = NRLEAF(rl); 762 break; 763 default: 764 abort(); 765 } 766 ++nxt; 767 r->linp[off] = r->upper -= nbytes; 768 memmove((char *)(void *)r + r->upper, src, nbytes); 769 } 770 temp = off * sizeof(indx_t); 771 _DBFIT(temp, indx_t); 772 r->lower += (indx_t)temp; 773 774 /* If the key is being appended to the page, adjust the index. */ 775 if (skip == top) 776 r->lower += sizeof(indx_t); 777 778 return (rval); 779 } 780 781 /* 782 * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 783 * 784 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 785 * record that references them gets deleted. Chains pointed to by internal 786 * pages never get deleted. This routine marks a chain as pointed to by an 787 * internal page. 788 * 789 * Parameters: 790 * t: tree 791 * pg: page number of first page in the chain. 792 * 793 * Returns: 794 * RET_SUCCESS, RET_ERROR. 795 */ 796 static int 797 bt_preserve(BTREE *t, pgno_t pg) 798 { 799 PAGE *h; 800 801 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 802 return (RET_ERROR); 803 h->flags |= P_PRESERVE; 804 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 805 return (RET_SUCCESS); 806 } 807 808 /* 809 * REC_TOTAL -- Return the number of recno entries below a page. 810 * 811 * Parameters: 812 * h: page 813 * 814 * Returns: 815 * The number of recno entries below a page. 816 * 817 * XXX 818 * These values could be set by the bt_psplit routine. The problem is that the 819 * entry has to be popped off of the stack etc. or the values have to be passed 820 * all the way back to bt_split/bt_rroot and it's not very clean. 821 */ 822 static recno_t 823 rec_total(PAGE *h) 824 { 825 recno_t recs; 826 indx_t nxt, top; 827 828 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 829 recs += GETRINTERNAL(h, nxt)->nrecs; 830 return (recs); 831 } 832