projects / unix-history / blame
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|---|---|---|
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1 | /*- |
| 2 | * Copyright (c) 1990 The Regents of the University of California. | |
| 3 | * All rights reserved. | |
| 4 | * | |
| 5 | * %sccs.include.redist.c% | |
| 6 | */ | |
| 7 | ||
| 8 | #if defined(LIBC_SCCS) && !defined(lint) | |
| 94ac72c5 | 9 | static char sccsid[] = "@(#)bt_page.c 5.3 (Berkeley) %G%"; |
| 8e21dcc0 KB |
10 | #endif /* LIBC_SCCS and not lint */ |
| 11 | ||
| 12 | #include <sys/types.h> | |
| 9f252354 | 13 | |
| 8e21dcc0 | 14 | #define __DBINTERFACE_PRIVATE |
| 8e21dcc0 KB |
15 | #include <stdio.h> |
| 16 | ||
| 94ac72c5 | 17 | #include <db.h> |
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18 | #include "btree.h" |
| 19 | ||
| 20 | /* | |
| 21 | * __BT_FREE -- Put a page on the freelist. | |
| 22 | * | |
| 23 | * Parameters: | |
| 24 | * t: tree | |
| 25 | * h: page to free | |
| 26 | * | |
| 27 | * Returns: | |
| 28 | * RET_ERROR, RET_SUCCESS | |
| 29 | */ | |
| 30 | int | |
| 31 | __bt_free(t, h) | |
| 32 | BTREE *t; | |
| 33 | PAGE *h; | |
| 34 | { | |
| 35 | /* Insert the page at the start of the free list. */ | |
| 36 | h->prevpg = P_INVALID; | |
| 37 | h->nextpg = t->bt_free; | |
| 38 | t->bt_free = h->pgno; | |
| 39 | ||
| 40 | /* Make sure the page gets written back. */ | |
| 41 | return (mpool_put(t->bt_mp, h, MPOOL_DIRTY)); | |
| 42 | } | |
| 43 | ||
| 44 | /* | |
| 45 | * __BT_NEW -- Get a new page, preferably from the freelist. | |
| 46 | * | |
| 47 | * Parameters: | |
| 48 | * t: tree | |
| 49 | * npg: storage for page number. | |
| 50 | * | |
| 51 | * Returns: | |
| 52 | * Pointer to a page, NULL on error. | |
| 53 | */ | |
| 54 | PAGE * | |
| 55 | __bt_new(t, npg) | |
| 56 | BTREE *t; | |
| 57 | pgno_t *npg; | |
| 58 | { | |
| 59 | PAGE *h; | |
| 60 | ||
| 61 | if (t->bt_free != P_INVALID && | |
| 62 | (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) { | |
| 63 | *npg = t->bt_free; | |
| 64 | t->bt_free = h->nextpg; | |
| 65 | return (h); | |
| 66 | } | |
| 67 | return (mpool_new(t->bt_mp, npg)); | |
| 68 | } |