diff options
Diffstat (limited to 'db2/btree/bt_delete.c')
| -rw-r--r-- | db2/btree/bt_delete.c | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/db2/btree/bt_delete.c b/db2/btree/bt_delete.c new file mode 100644 index 0000000000..e7ec4dfe3e --- /dev/null +++ b/db2/btree/bt_delete.c @@ -0,0 +1,607 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. All rights reserved. + */ +/* + * Copyright (c) 1990, 1993, 1994, 1995, 1996 + * Keith Bostic. All rights reserved. + */ +/* + * Copyright (c) 1990, 1993, 1994, 1995 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Mike Olson. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include "config.h" + +#ifndef lint +static const char sccsid[] = "@(#)bt_delete.c 10.18 (Sleepycat) 8/24/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> + +#include <stdio.h> +#include <string.h> +#endif + +#include "db_int.h" +#include "db_page.h" +#include "btree.h" + +static int __bam_dpages __P((DB *, BTREE *)); + +/* + * __bam_delete -- + * Delete the items referenced by a key. + * + * PUBLIC: int __bam_delete __P((DB *, DB_TXN *, DBT *, int)); + */ +int +__bam_delete(argdbp, txn, key, flags) + DB *argdbp; + DB_TXN *txn; + DBT *key; + int flags; +{ + BTREE *t; + DB *dbp; + PAGE *h; + db_indx_t cnt, i, indx; + int dpage, exact, ret, stack; + + DEBUG_LWRITE(argdbp, txn, "bam_delete", key, NULL, flags); + + stack = 0; + + /* Check for invalid flags. */ + if ((ret = + __db_delchk(argdbp, flags, F_ISSET(argdbp, DB_AM_RDONLY))) != 0) + return (ret); + + GETHANDLE(argdbp, txn, &dbp, ret); + t = dbp->internal; + + /* Search the tree for the key; delete only deletes exact matches. */ + if ((ret = __bam_search(dbp, key, S_DELETE, 1, NULL, &exact)) != 0) + goto err; + stack = 1; + h = t->bt_csp->page; + indx = t->bt_csp->indx; + + /* Delete the key/data pair, including any duplicates. */ + for (cnt = 1, i = indx;; ++cnt) + if ((i += P_INDX) >= NUM_ENT(h) || h->inp[i] != h->inp[indx]) + break; + for (; cnt > 0; --cnt, ++t->lstat.bt_deleted) + if (__bam_ca_delete(dbp, h->pgno, indx, NULL) != 0) { + GET_BKEYDATA(h, indx + O_INDX)->deleted = 1; + indx += P_INDX; + } else if ((ret = __bam_ditem(dbp, h, indx)) != 0 || + (ret = __bam_ditem(dbp, h, indx)) != 0) + goto err; + + /* If we're using record numbers, update internal page record counts. */ + if (F_ISSET(dbp, DB_BT_RECNUM) && (ret = __bam_adjust(dbp, t, -1)) != 0) + goto err; + + /* If the page is now empty, delete it. */ + dpage = NUM_ENT(h) == 0 && h->pgno != PGNO_ROOT; + + __bam_stkrel(dbp); + stack = 0; + + ret = dpage ? __bam_dpage(dbp, key) : 0; + +err: if (stack) + __bam_stkrel(dbp); + PUTHANDLE(dbp); + return (ret); +} + +/* + * __ram_delete -- + * Delete the items referenced by a key. + * + * PUBLIC: int __ram_delete __P((DB *, DB_TXN *, DBT *, int)); + */ +int +__ram_delete(argdbp, txn, key, flags) + DB *argdbp; + DB_TXN *txn; + DBT *key; + int flags; +{ + BKEYDATA bk; + BTREE *t; + DB *dbp; + DBT hdr, data; + PAGE *h; + db_indx_t indx; + db_recno_t recno; + int exact, ret, stack; + + stack = 0; + + /* Check for invalid flags. */ + if ((ret = + __db_delchk(argdbp, flags, F_ISSET(argdbp, DB_AM_RDONLY))) != 0) + return (ret); + + GETHANDLE(argdbp, txn, &dbp, ret); + t = dbp->internal; + + /* Check the user's record number and fill in as necessary. */ + if ((ret = __ram_getno(argdbp, key, &recno, 0)) != 0) + goto err; + + /* Search the tree for the key; delete only deletes exact matches. */ + if ((ret = __bam_rsearch(dbp, &recno, S_DELETE, 1, &exact)) != 0) + goto err; + if (!exact) { + ret = DB_NOTFOUND; + goto err; + } + + h = t->bt_csp->page; + indx = t->bt_csp->indx; + stack = 1; + + /* If the record has already been deleted, we couldn't have found it. */ + if (GET_BKEYDATA(h, indx)->deleted) { + ret = DB_KEYEMPTY; + goto done; + } + + /* + * If we're not renumbering records, replace the record with a marker + * and return. + */ + if (!F_ISSET(dbp, DB_RE_RENUMBER)) { + if ((ret = __bam_ditem(dbp, h, indx)) != 0) + goto err; + + bk.deleted = 1; + bk.type = B_KEYDATA; + bk.len = 0; + memset(&hdr, 0, sizeof(hdr)); + hdr.data = &bk; + hdr.size = SSZA(BKEYDATA, data); + memset(&data, 0, sizeof(data)); + data.data = (char *) ""; + data.size = 0; + if ((ret = __db_pitem(dbp, + h, indx, BKEYDATA_SIZE(0), &hdr, &data)) != 0) + goto err; + + ++t->lstat.bt_deleted; + goto done; + } + + /* Delete the item. */ + if ((ret = __bam_ditem(dbp, h, indx)) != 0) + goto err; + + ++t->lstat.bt_deleted; + if (t->bt_recno != NULL) + F_SET(t->bt_recno, RECNO_MODIFIED); + + /* Adjust the counts. */ + __bam_adjust(dbp, t, -1); + + /* Adjust the cursors. */ + __ram_ca(dbp, recno, CA_DELETE); + + /* + * If the page is now empty, delete it -- we have the whole tree + * locked, so there are no preparations to make. Else, release + * the pages. + */ + if (NUM_ENT(h) == 0 && h->pgno != PGNO_ROOT) { + stack = 0; + ret = __bam_dpages(dbp, t); + } + +done: +err: if (stack) + __bam_stkrel(dbp); + + PUTHANDLE(dbp); + return (ret); +} + +/* + * __bam_ditem -- + * Delete one or more entries from a page. + * + * PUBLIC: int __bam_ditem __P((DB *, PAGE *, u_int32_t)); + */ +int +__bam_ditem(dbp, h, indx) + DB *dbp; + PAGE *h; + u_int32_t indx; +{ + BINTERNAL *bi; + BKEYDATA *bk; + BOVERFLOW *bo; + u_int32_t nbytes; + int ret; + + switch (TYPE(h)) { + case P_IBTREE: + bi = GET_BINTERNAL(h, indx); + switch (bi->type) { + case B_DUPLICATE: + case B_OVERFLOW: + nbytes = BINTERNAL_SIZE(bi->len); + goto offpage; + case B_KEYDATA: + nbytes = BKEYDATA_SIZE(bi->len); + break; + default: + return (__db_pgfmt(dbp, h->pgno)); + } + break; + case P_IRECNO: + nbytes = RINTERNAL_SIZE; + break; + case P_LBTREE: + /* + * If it's a duplicate key, discard the index and don't touch + * the actual page item. This works because no data item can + * have an index that matches any other index so even if the + * data item is in an index "slot", it won't match any other + * index. + */ + if (!(indx % 2)) { + if (indx > 0 && h->inp[indx] == h->inp[indx - P_INDX]) + return (__bam_adjindx(dbp, + h, indx, indx - P_INDX, 0)); + if (indx < (u_int32_t)(NUM_ENT(h) - P_INDX) && + h->inp[indx] == h->inp[indx + P_INDX]) + return (__bam_adjindx(dbp, + h, indx, indx + O_INDX, 0)); + } + /* FALLTHROUGH */ + case P_LRECNO: + bk = GET_BKEYDATA(h, indx); + switch (bk->type) { + case B_DUPLICATE: + case B_OVERFLOW: + nbytes = BOVERFLOW_SIZE; + +offpage: /* Delete duplicate/offpage chains. */ + bo = GET_BOVERFLOW(h, indx); + if (bo->type == B_DUPLICATE) { + if ((ret = + __db_ddup(dbp, bo->pgno, __bam_free)) != 0) + return (ret); + } else + if ((ret = + __db_doff(dbp, bo->pgno, __bam_free)) != 0) + return (ret); + break; + case B_KEYDATA: + nbytes = BKEYDATA_SIZE(bk->len); + break; + default: + return (__db_pgfmt(dbp, h->pgno)); + } + break; + default: + return (__db_pgfmt(dbp, h->pgno)); + } + + /* Delete the item. */ + if ((ret = __db_ditem(dbp, h, indx, nbytes)) != 0) + return (ret); + + /* Mark the page dirty. */ + return (memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY)); +} + +/* + * __bam_adjindx -- + * Adjust an index on the page. + * + * PUBLIC: int __bam_adjindx __P((DB *, PAGE *, u_int32_t, u_int32_t, int)); + */ +int +__bam_adjindx(dbp, h, indx, indx_copy, is_insert) + DB *dbp; + PAGE *h; + u_int32_t indx, indx_copy; + int is_insert; +{ + db_indx_t copy; + int ret; + + /* Log the change. */ + if (DB_LOGGING(dbp) && + (ret = __bam_adj_log(dbp->dbenv->lg_info, dbp->txn, &LSN(h), + 0, dbp->log_fileid, PGNO(h), &LSN(h), indx, indx_copy, + (u_int32_t)is_insert)) != 0) + return (ret); + + if (is_insert) { + copy = h->inp[indx_copy]; + if (indx != NUM_ENT(h)) + memmove(&h->inp[indx + O_INDX], &h->inp[indx], + sizeof(db_indx_t) * (NUM_ENT(h) - indx)); + h->inp[indx] = copy; + ++NUM_ENT(h); + } else { + --NUM_ENT(h); + if (indx != NUM_ENT(h)) + memmove(&h->inp[indx], &h->inp[indx + O_INDX], + sizeof(db_indx_t) * (NUM_ENT(h) - indx)); + } + + /* Mark the page dirty. */ + ret = memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY); + + /* Adjust the cursors. */ + __bam_ca_di(dbp, h->pgno, indx, is_insert ? 1 : -1); + return (0); +} + +/* + * __bam_dpage -- + * Delete a page from the tree. + * + * PUBLIC: int __bam_dpage __P((DB *, const DBT *)); + */ +int +__bam_dpage(dbp, key) + DB *dbp; + const DBT *key; +{ + BTREE *t; + DB_LOCK lock; + PAGE *h; + db_pgno_t pgno; + int exact, level, ret; + + ret = 0; + t = dbp->internal; + + /* + * The locking protocol is that we acquire locks by walking down the + * tree, to avoid the obvious deadlocks. + * + * Call __bam_search to reacquire the empty leaf page, but this time + * get both the leaf page and it's parent, locked. Walk back up the + * tree, until we have the top pair of pages that we want to delete. + * Once we have the top page that we want to delete locked, lock the + * underlying pages and check to make sure they're still empty. If + * they are, delete them. + */ + for (level = LEAFLEVEL;; ++level) { + /* Acquire a page and its parent, locked. */ + if ((ret = + __bam_search(dbp, key, S_WRPAIR, level, NULL, &exact)) != 0) + return (ret); + + /* + * If we reach the root or the page isn't going to be empty + * when we delete one record, quit. + */ + h = t->bt_csp[-1].page; + if (h->pgno == PGNO_ROOT || NUM_ENT(h) != 1) + break; + + /* Release the two locked pages. */ + (void)memp_fput(dbp->mpf, t->bt_csp[-1].page, 0); + (void)__BT_TLPUT(dbp, t->bt_csp[-1].lock); + (void)memp_fput(dbp->mpf, t->bt_csp[0].page, 0); + (void)__BT_TLPUT(dbp, t->bt_csp[0].lock); + } + + /* + * Leave the stack pointer one after the last entry, we may be about + * to push more items on the stack. + */ + ++t->bt_csp; + + /* + * t->bt_csp[-2].page is the top page, which we're not going to delete, + * and t->bt_csp[-1].page is the first page we are going to delete. + * + * Walk down the chain, acquiring the rest of the pages until we've + * retrieved the leaf page. If we find any pages that aren't going + * to be emptied by the delete, someone else added something while we + * were walking the tree, and we discontinue the delete. + */ + for (h = t->bt_csp[-1].page;;) { + if (ISLEAF(h)) { + if (NUM_ENT(h) != 0) + goto release; + break; + } else + if (NUM_ENT(h) != 1) + goto release; + + /* + * Get the next page, write lock it and push it onto the stack. + * We know it's index 0, because it can only have one element. + */ + pgno = TYPE(h) == P_IBTREE ? + GET_BINTERNAL(h, 0)->pgno : GET_RINTERNAL(h, 0)->pgno; + + if ((ret = __bam_lget(dbp, 0, pgno, DB_LOCK_WRITE, &lock)) != 0) + goto release; + if ((ret = __bam_pget(dbp, &h, &pgno, 0)) != 0) + goto release; + BT_STK_PUSH(t, h, 0, lock, ret); + if (ret != 0) + goto release; + } + + BT_STK_POP(t); + return (__bam_dpages(dbp, t)); + +release: + /* Discard any locked pages and return. */ + BT_STK_POP(t); + __bam_stkrel(dbp); + return (ret); +} + +/* + * __bam_dpages -- + * Delete a set of locked pages. + */ +static int +__bam_dpages(dbp, t) + DB *dbp; + BTREE *t; +{ + DBT a, b; + DB_LOCK lock; + EPG *epg; + PAGE *h; + db_pgno_t pgno; + db_recno_t rcnt; + int ret; + + rcnt = 0; /* XXX: Shut the compiler up. */ + epg = t->bt_sp; + + /* + * !!! + * There is an interesting deadlock situation here. We have to relink + * the leaf page chain around the leaf page being deleted. Consider + * a cursor walking through the leaf pages, that has the previous page + * read-locked and is waiting on a lock for the page we're deleting. + * It will deadlock here. This is a problem, because if our process is + * selected to resolve the deadlock, we'll leave an empty leaf page + * that we can never again access by walking down the tree. So, before + * we unlink the subtree, we relink the leaf page chain. + */ + if ((ret = __db_relink(dbp, t->bt_csp->page, NULL, 1)) != 0) + goto release; + + /* + * We have the entire stack of deletable pages locked. Start from the + * top of the tree and move to the bottom, as it's better to release + * the inner pages as soon as possible. + */ + if ((ret = __bam_ditem(dbp, epg->page, epg->indx)) != 0) + goto release; + + /* + * If we deleted the next-to-last item from the root page, the tree + * has collapsed a level. Try and write lock the remaining root + 1 + * page and copy it onto the root page. If we can't get the lock, + * that's okay, the tree just stays a level deeper than we'd like. + */ + h = epg->page; + if (h->pgno == PGNO_ROOT && NUM_ENT(h) == 1) { + pgno = TYPE(epg->page) == P_IBTREE ? + GET_BINTERNAL(epg->page, 0)->pgno : + GET_RINTERNAL(epg->page, 0)->pgno; + if ((ret = __bam_lget(dbp, 0, pgno, DB_LOCK_WRITE, &lock)) != 0) + goto release; + if ((ret = __bam_pget(dbp, &h, &pgno, 0)) != 0) + goto release; + + /* Log the change. */ + if (DB_LOGGING(dbp)) { + memset(&a, 0, sizeof(a)); + a.data = h; + a.size = dbp->pgsize; + memset(&b, 0, sizeof(b)); + b.data = P_ENTRY(epg->page, 0); + b.size = BINTERNAL_SIZE(((BINTERNAL *)b.data)->len); + __bam_rsplit_log(dbp->dbenv->lg_info, dbp->txn, + &h->lsn, 0, dbp->log_fileid, h->pgno, &a, &b, + &epg->page->lsn); + } + + /* + * Make the switch. + * + * One fixup -- if the tree has record numbers and we're not + * converting to a leaf page, we have to preserve the total + * record count. + */ + if (TYPE(h) == P_IRECNO || + (TYPE(h) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM))) + rcnt = RE_NREC(epg->page); + memcpy(epg->page, h, dbp->pgsize); + epg->page->pgno = PGNO_ROOT; + if (TYPE(h) == P_IRECNO || + (TYPE(h) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM))) + RE_NREC_SET(epg->page, rcnt); + + /* Free the last page in that level of the btree. */ + ++t->lstat.bt_freed; + (void)__bam_free(dbp, h); + + /* Adjust the cursors. */ + __bam_ca_move(dbp, t, h->pgno, PGNO_ROOT); + + (void)__BT_TLPUT(dbp, lock); + } + + /* Release the top page in the subtree. */ + (void)memp_fput(dbp->mpf, epg->page, 0); + (void)__BT_TLPUT(dbp, epg->lock); + + /* + * Free the rest of the pages. + * + * XXX + * Don't bother checking for errors. We've unlinked the subtree from + * the tree, and there's no possibility of recovery. + */ + for (; ++epg <= t->bt_csp; ++t->lstat.bt_freed) { + if (NUM_ENT(epg->page) != 0) + (void)__bam_ditem(dbp, epg->page, epg->indx); + + (void)__bam_free(dbp, epg->page); + (void)__BT_TLPUT(dbp, epg->lock); + } + return (0); + +release: + /* Discard any remaining pages and return. */ + for (; epg <= t->bt_csp; ++epg) { + (void)memp_fput(dbp->mpf, epg->page, 0); + (void)__BT_TLPUT(dbp, epg->lock); + } + return (ret); +} |