1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)bt_page.c 8.2 (Berkeley) 02/21/94"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <sys/types.h> 13 14 #include <stdio.h> 15 16 #include <db.h> 17 #include "btree.h" 18 19 /* 20 * __BT_FREE -- Put a page on the freelist. 21 * 22 * Parameters: 23 * t: tree 24 * h: page to free 25 * 26 * Returns: 27 * RET_ERROR, RET_SUCCESS 28 */ 29 int 30 __bt_free(t, h) 31 BTREE *t; 32 PAGE *h; 33 { 34 /* Insert the page at the start of the free list. */ 35 h->prevpg = P_INVALID; 36 h->nextpg = t->bt_free; 37 t->bt_free = h->pgno; 38 39 /* Make sure the page gets written back. */ 40 return (mpool_put(t->bt_mp, h, MPOOL_DIRTY)); 41 } 42 43 /* 44 * __BT_NEW -- Get a new page, preferably from the freelist. 45 * 46 * Parameters: 47 * t: tree 48 * npg: storage for page number. 49 * 50 * Returns: 51 * Pointer to a page, NULL on error. 52 */ 53 PAGE * 54 __bt_new(t, npg) 55 BTREE *t; 56 pgno_t *npg; 57 { 58 PAGE *h; 59 60 if (t->bt_free != P_INVALID && 61 (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) { 62 *npg = t->bt_free; 63 t->bt_free = h->nextpg; 64 return (h); 65 } 66 return (mpool_new(t->bt_mp, npg)); 67 } 68