/*- * Copyright (c) 1990, 1993, 1994 * 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. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)bt_seq.c 8.7 (Berkeley) 7/20/94"; #endif /* LIBC_SCCS and not lint */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: src/lib/libc/db/btree/bt_seq.c,v 1.3 2002/03/21 22:46:25 obrien Exp $"); #include <sys/types.h> #include <errno.h> #include <stddef.h> #include <stdio.h> #include <stdlib.h> #include <db.h> #include "btree.h" static int __bt_first(BTREE *, const DBT *, EPG *, int *); static int __bt_seqadv(BTREE *, EPG *, int); static int __bt_seqset(BTREE *, EPG *, DBT *, int); /* * Sequential scan support. * * The tree can be scanned sequentially, starting from either end of the * tree or from any specific key. A scan request before any scanning is * done is initialized as starting from the least node. */ /* * __bt_seq -- * Btree sequential scan interface. * * Parameters: * dbp: pointer to access method * key: key for positioning and return value * data: data return value * flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV. * * Returns: * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key. */ int __bt_seq(dbp, key, data, flags) const DB *dbp; DBT *key, *data; u_int flags; { BTREE *t; EPG e; int status; t = dbp->internal; /* Toss any page pinned across calls. */ if (t->bt_pinned != NULL) { mpool_put(t->bt_mp, t->bt_pinned, 0); t->bt_pinned = NULL; } /* * If scan unitialized as yet, or starting at a specific record, set * the scan to a specific key. Both __bt_seqset and __bt_seqadv pin * the page the cursor references if they're successful. */ switch (flags) { case R_NEXT: case R_PREV: if (F_ISSET(&t->bt_cursor, CURS_INIT)) { status = __bt_seqadv(t, &e, flags); break; } /* FALLTHROUGH */ case R_FIRST: case R_LAST: case R_CURSOR: status = __bt_seqset(t, &e, key, flags); break; default: errno = EINVAL; return (RET_ERROR); } if (status == RET_SUCCESS) { __bt_setcur(t, e.page->pgno, e.index); status = __bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0); /* * If the user is doing concurrent access, we copied the * key/data, toss the page. */ if (F_ISSET(t, B_DB_LOCK)) mpool_put(t->bt_mp, e.page, 0); else t->bt_pinned = e.page; } return (status); } /* * __bt_seqset -- * Set the sequential scan to a specific key. * * Parameters: * t: tree * ep: storage for returned key * key: key for initial scan position * flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV * * Side effects: * Pins the page the cursor references. * * Returns: * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key. */ static int __bt_seqset(t, ep, key, flags) BTREE *t; EPG *ep; DBT *key; int flags; { PAGE *h; pgno_t pg; int exact; /* * Find the first, last or specific key in the tree and point the * cursor at it. The cursor may not be moved until a new key has * been found. */ switch (flags) { case R_CURSOR: /* Keyed scan. */ /* * Find the first instance of the key or the smallest key * which is greater than or equal to the specified key. */ if (key->data == NULL || key->size == 0) { errno = EINVAL; return (RET_ERROR); } return (__bt_first(t, key, ep, &exact)); case R_FIRST: /* First record. */ case R_NEXT: /* Walk down the left-hand side of the tree. */ for (pg = P_ROOT;;) { if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (RET_ERROR); /* Check for an empty tree. */ if (NEXTINDEX(h) == 0) { mpool_put(t->bt_mp, h, 0); return (RET_SPECIAL); } if (h->flags & (P_BLEAF | P_RLEAF)) break; pg = GETBINTERNAL(h, 0)->pgno; mpool_put(t->bt_mp, h, 0); } ep->page = h; ep->index = 0; break; case R_LAST: /* Last record. */ case R_PREV: /* Walk down the right-hand side of the tree. */ for (pg = P_ROOT;;) { if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (RET_ERROR); /* Check for an empty tree. */ if (NEXTINDEX(h) == 0) { mpool_put(t->bt_mp, h, 0); return (RET_SPECIAL); } if (h->flags & (P_BLEAF | P_RLEAF)) break; pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno; mpool_put(t->bt_mp, h, 0); } ep->page = h; ep->index = NEXTINDEX(h) - 1; break; } return (RET_SUCCESS); } /* * __bt_seqadvance -- * Advance the sequential scan. * * Parameters: * t: tree * flags: R_NEXT, R_PREV * * Side effects: * Pins the page the new key/data record is on. * * Returns: * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key. */ static int __bt_seqadv(t, ep, flags) BTREE *t; EPG *ep; int flags; { CURSOR *c; PAGE *h; indx_t index; pgno_t pg; int exact; /* * There are a couple of states that we can be in. The cursor has * been initialized by the time we get here, but that's all we know. */ c = &t->bt_cursor; /* * The cursor was deleted where there weren't any duplicate records, * so the key was saved. Find out where that key would go in the * current tree. It doesn't matter if the returned key is an exact * match or not -- if it's an exact match, the record was added after * the delete so we can just return it. If not, as long as there's * a record there, return it. */ if (F_ISSET(c, CURS_ACQUIRE)) return (__bt_first(t, &c->key, ep, &exact)); /* Get the page referenced by the cursor. */ if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL) return (RET_ERROR); /* * Find the next/previous record in the tree and point the cursor at * it. The cursor may not be moved until a new key has been found. */ switch (flags) { case R_NEXT: /* Next record. */ /* * The cursor was deleted in duplicate records, and moved * forward to a record that has yet to be returned. Clear * that flag, and return the record. */ if (F_ISSET(c, CURS_AFTER)) goto usecurrent; index = c->pg.index; if (++index == NEXTINDEX(h)) { pg = h->nextpg; mpool_put(t->bt_mp, h, 0); if (pg == P_INVALID) return (RET_SPECIAL); if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (RET_ERROR); index = 0; } break; case R_PREV: /* Previous record. */ /* * The cursor was deleted in duplicate records, and moved * backward to a record that has yet to be returned. Clear * that flag, and return the record. */ if (F_ISSET(c, CURS_BEFORE)) { usecurrent: F_CLR(c, CURS_AFTER | CURS_BEFORE); ep->page = h; ep->index = c->pg.index; return (RET_SUCCESS); } index = c->pg.index; if (index == 0) { pg = h->prevpg; mpool_put(t->bt_mp, h, 0); if (pg == P_INVALID) return (RET_SPECIAL); if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (RET_ERROR); index = NEXTINDEX(h) - 1; } else --index; break; } ep->page = h; ep->index = index; return (RET_SUCCESS); } /* * __bt_first -- * Find the first entry. * * Parameters: * t: the tree * key: the key * erval: return EPG * exactp: pointer to exact match flag * * Returns: * The first entry in the tree greater than or equal to key, * or RET_SPECIAL if no such key exists. */ static int __bt_first(t, key, erval, exactp) BTREE *t; const DBT *key; EPG *erval; int *exactp; { PAGE *h; EPG *ep, save; pgno_t pg; /* * Find any matching record; __bt_search pins the page. * * If it's an exact match and duplicates are possible, walk backwards * in the tree until we find the first one. Otherwise, make sure it's * a valid key (__bt_search may return an index just past the end of a * page) and return it. */ if ((ep = __bt_search(t, key, exactp)) == NULL) return (0); if (*exactp) { if (F_ISSET(t, B_NODUPS)) { *erval = *ep; return (RET_SUCCESS); } /* * Walk backwards, as long as the entry matches and there are * keys left in the tree. Save a copy of each match in case * we go too far. */ save = *ep; h = ep->page; do { if (save.page->pgno != ep->page->pgno) { mpool_put(t->bt_mp, save.page, 0); save = *ep; } else save.index = ep->index; /* * Don't unpin the page the last (or original) match * was on, but make sure it's unpinned if an error * occurs. */ if (ep->index == 0) { PAGE *hprev; if (h->prevpg == P_INVALID) break; if (h->pgno != save.page->pgno) mpool_put(t->bt_mp, h, 0); if ((hprev = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL) { if (h->pgno == save.page->pgno) mpool_put(t->bt_mp, save.page, 0); return (RET_ERROR); } ep->page = h = hprev; ep->index = NEXTINDEX(h); } --ep->index; } while (__bt_cmp(t, key, ep) == 0); /* * Reach here with the last page that was looked at pinned, * which may or may not be the same as the last (or original) * match page. If it's not useful, release it. */ if (h->pgno != save.page->pgno) mpool_put(t->bt_mp, h, 0); *erval = save; return (RET_SUCCESS); } /* If at the end of a page, find the next entry. */ if (ep->index == NEXTINDEX(ep->page)) { h = ep->page; pg = h->nextpg; mpool_put(t->bt_mp, h, 0); if (pg == P_INVALID) return (RET_SPECIAL); if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (RET_ERROR); ep->index = 0; ep->page = h; } *erval = *ep; return (RET_SUCCESS); } /* * __bt_setcur -- * Set the cursor to an entry in the tree. * * Parameters: * t: the tree * pgno: page number * index: page index */ void __bt_setcur(t, pgno, index) BTREE *t; pgno_t pgno; u_int index; { /* Lose any already deleted key. */ if (t->bt_cursor.key.data != NULL) { free(t->bt_cursor.key.data); t->bt_cursor.key.size = 0; t->bt_cursor.key.data = NULL; } F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE); /* Update the cursor. */ t->bt_cursor.pg.pgno = pgno; t->bt_cursor.pg.index = index; F_SET(&t->bt_cursor, CURS_INIT); }