+++ /dev/null
-/* Copyright 2000-2005 The Apache Software Foundation or its licensors, as
- * applicable.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/*
- * sdbm - ndbm work-alike hashed database library
- * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
- * author: oz@nexus.yorku.ca
- * status: ex-public domain.
- *
- * page-level routines
- */
-
-#include "apr_sdbm.h"
-
-#include "sdbm_tune.h"
-#include "sdbm_pair.h"
-#include "sdbm_private.h"
-
-#include <string.h> /* for memset() */
-
-
-#define exhash(item) sdbm_hash((item).dptr, (item).dsize)
-
-/*
- * forward
- */
-static int seepair(char *, int, char *, int);
-
-/*
- * page format:
- * +------------------------------+
- * ino | n | keyoff | datoff | keyoff |
- * +------------+--------+--------+
- * | datoff | - - - ----> |
- * +--------+---------------------+
- * | F R E E A R E A |
- * +--------------+---------------+
- * | <---- - - - | data |
- * +--------+-----+----+----------+
- * | key | data | key |
- * +--------+----------+----------+
- *
- * calculating the offsets for free area: if the number
- * of entries (ino[0]) is zero, the offset to the END of
- * the free area is the block size. Otherwise, it is the
- * nth (ino[ino[0]]) entry's offset.
- */
-
-int
-fitpair(pag, need)
-char *pag;
-int need;
-{
- register int n;
- register int off;
- register int avail;
- register short *ino = (short *) pag;
-
- off = ((n = ino[0]) > 0) ? ino[n] : PBLKSIZ;
- avail = off - (n + 1) * sizeof(short);
- need += 2 * sizeof(short);
-
- debug(("avail %d need %d\n", avail, need));
-
- return need <= avail;
-}
-
-void
-putpair(pag, key, val)
-char *pag;
-apr_sdbm_datum_t key;
-apr_sdbm_datum_t val;
-{
- register int n;
- register int off;
- register short *ino = (short *) pag;
-
- off = ((n = ino[0]) > 0) ? ino[n] : PBLKSIZ;
-/*
- * enter the key first
- */
- off -= key.dsize;
- (void) memcpy(pag + off, key.dptr, key.dsize);
- ino[n + 1] = off;
-/*
- * now the data
- */
- off -= val.dsize;
- (void) memcpy(pag + off, val.dptr, val.dsize);
- ino[n + 2] = off;
-/*
- * adjust item count
- */
- ino[0] += 2;
-}
-
-apr_sdbm_datum_t
-getpair(pag, key)
-char *pag;
-apr_sdbm_datum_t key;
-{
- register int i;
- register int n;
- apr_sdbm_datum_t val;
- register short *ino = (short *) pag;
-
- if ((n = ino[0]) == 0)
- return sdbm_nullitem;
-
- if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
- return sdbm_nullitem;
-
- val.dptr = pag + ino[i + 1];
- val.dsize = ino[i] - ino[i + 1];
- return val;
-}
-
-int
-duppair(pag, key)
-char *pag;
-apr_sdbm_datum_t key;
-{
- register short *ino = (short *) pag;
- return ino[0] > 0 && seepair(pag, ino[0], key.dptr, key.dsize) > 0;
-}
-
-apr_sdbm_datum_t
-getnkey(pag, num)
-char *pag;
-int num;
-{
- apr_sdbm_datum_t key;
- register int off;
- register short *ino = (short *) pag;
-
- num = num * 2 - 1;
- if (ino[0] == 0 || num > ino[0])
- return sdbm_nullitem;
-
- off = (num > 1) ? ino[num - 1] : PBLKSIZ;
-
- key.dptr = pag + ino[num];
- key.dsize = off - ino[num];
-
- return key;
-}
-
-int
-delpair(pag, key)
-char *pag;
-apr_sdbm_datum_t key;
-{
- register int n;
- register int i;
- register short *ino = (short *) pag;
-
- if ((n = ino[0]) == 0)
- return 0;
-
- if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
- return 0;
-/*
- * found the key. if it is the last entry
- * [i.e. i == n - 1] we just adjust the entry count.
- * hard case: move all data down onto the deleted pair,
- * shift offsets onto deleted offsets, and adjust them.
- * [note: 0 < i < n]
- */
- if (i < n - 1) {
- register int m;
- register char *dst = pag + (i == 1 ? PBLKSIZ : ino[i - 1]);
- register char *src = pag + ino[i + 1];
- register int zoo = dst - src;
-
- debug(("free-up %d ", zoo));
-/*
- * shift data/keys down
- */
- m = ino[i + 1] - ino[n];
-
-#undef DUFF /* just use memmove. it should be plenty fast. */
-#ifdef DUFF
-#define MOVB *--dst = *--src
-
- if (m > 0) {
- register int loop = (m + 8 - 1) >> 3;
-
- switch (m & (8 - 1)) {
- case 0: do {
- MOVB; case 7: MOVB;
- case 6: MOVB; case 5: MOVB;
- case 4: MOVB; case 3: MOVB;
- case 2: MOVB; case 1: MOVB;
- } while (--loop);
- }
- }
-#else
- dst -= m;
- src -= m;
- memmove(dst, src, m);
-#endif
-
-/*
- * adjust offset index up
- */
- while (i < n - 1) {
- ino[i] = ino[i + 2] + zoo;
- i++;
- }
- }
- ino[0] -= 2;
- return 1;
-}
-
-/*
- * search for the key in the page.
- * return offset index in the range 0 < i < n.
- * return 0 if not found.
- */
-static int
-seepair(pag, n, key, siz)
-char *pag;
-register int n;
-register char *key;
-register int siz;
-{
- register int i;
- register int off = PBLKSIZ;
- register short *ino = (short *) pag;
-
- for (i = 1; i < n; i += 2) {
- if (siz == off - ino[i] &&
- memcmp(key, pag + ino[i], siz) == 0)
- return i;
- off = ino[i + 1];
- }
- return 0;
-}
-
-void
-splpage(pag, new, sbit)
-char *pag;
-char *new;
-long sbit;
-{
- apr_sdbm_datum_t key;
- apr_sdbm_datum_t val;
-
- register int n;
- register int off = PBLKSIZ;
- char cur[PBLKSIZ];
- register short *ino = (short *) cur;
-
- (void) memcpy(cur, pag, PBLKSIZ);
- (void) memset(pag, 0, PBLKSIZ);
- (void) memset(new, 0, PBLKSIZ);
-
- n = ino[0];
- for (ino++; n > 0; ino += 2) {
- key.dptr = cur + ino[0];
- key.dsize = off - ino[0];
- val.dptr = cur + ino[1];
- val.dsize = ino[0] - ino[1];
-/*
- * select the page pointer (by looking at sbit) and insert
- */
- (void) putpair((exhash(key) & sbit) ? new : pag, key, val);
-
- off = ino[1];
- n -= 2;
- }
-
- debug(("%d split %d/%d\n", ((short *) cur)[0] / 2,
- ((short *) new)[0] / 2,
- ((short *) pag)[0] / 2));
-}
-
-/*
- * check page sanity:
- * number of entries should be something
- * reasonable, and all offsets in the index should be in order.
- * this could be made more rigorous.
- */
-int
-chkpage(pag)
-char *pag;
-{
- register int n;
- register int off;
- register short *ino = (short *) pag;
-
- if ((n = ino[0]) < 0 || n > PBLKSIZ / sizeof(short))
- return 0;
-
- if (n > 0) {
- off = PBLKSIZ;
- for (ino++; n > 0; ino += 2) {
- if (ino[0] > off || ino[1] > off ||
- ino[1] > ino[0])
- return 0;
- off = ino[1];
- n -= 2;
- }
- }
- return 1;
-}
Code Review / bottlenecks.git / blobdiff