386 lines
9.8 KiB
C
386 lines
9.8 KiB
C
/* $XdotOrg: $ */
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/* $Xorg: cache.c,v 1.4 2001/02/09 02:05:42 xorgcvs Exp $ */
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/*
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Copyright 1987, 1998 The Open Group
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Permission to use, copy, modify, distribute, and sell this software and its
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documentation for any purpose is hereby granted without fee, provided that
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the above copyright notice appear in all copies and that both that
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copyright notice and this permission notice appear in supporting
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documentation.
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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Except as contained in this notice, the name of The Open Group shall not be
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used in advertising or otherwise to promote the sale, use or other dealings
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in this Software without prior written authorization from The Open Group.
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* Copyright 1990, 1991 Network Computing Devices;
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* Portions Copyright 1987 by Digital Equipment Corporation
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*
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* Permission to use, copy, modify, distribute, and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice appear in all copies and that both that
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* copyright notice and this permission notice appear in supporting
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* documentation, and that the names of Network Computing Devices,
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* or Digital not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. Network Computing Devices, or Digital
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* make no representations about the
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* suitability of this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*
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* NETWORK COMPUTING DEVICES, AND DIGITAL DISCLAIM ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS, IN NO EVENT SHALL NETWORK COMPUTING DEVICES, OR DIGITAL BE
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* LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* @(#)cache.c 4.2 91/05/02
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*
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*/
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/* $XFree86: xc/programs/xfs/difs/cache.c,v 1.6 2001/12/14 20:01:33 dawes Exp $ */
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#include "cachestr.h"
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#include "misc.h"
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#define INITBUCKETS 64
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#define INITHASHSIZE 6
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#define MAXHASHSIZE 11
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#define ENTRYOFFSET 22
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#define CACHE_ENTRY_MASK 0x3FFFFF
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#define CACHE_ENTRY_BITS(id) ((id) & 0x1fc00000)
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#define CACHE_ID(id) ((int)(CACHE_ENTRY_BITS(id) >> ENTRYOFFSET))
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#define NullCacheEntry ((CacheEntryPtr) 0)
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#define MAX_NUM_CACHES 32
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/* XXX make this dynamic? */
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static CachePtr caches[MAX_NUM_CACHES];
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static int num_caches = 1;
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/*-
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* Notes on cache implementation
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*
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* This is basically the X11 resource code, with some modifications
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* to handle aging.
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*
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* Its currently optimized for lookup & store. Flushing old stuff
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* is a lot slower than it should probably be, but there's tradeoffs
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* in tuning.
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*/
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Cache
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CacheInit(unsigned long maxsize)
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{
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Cache id = (Cache) num_caches;
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CachePtr cache;
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cache = (CachePtr) fsalloc(sizeof(CacheRec));
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if (!cache)
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return (Cache) 0;
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cache->entries = (CacheEntryPtr *)
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fsalloc(INITBUCKETS * sizeof(CacheEntryPtr));
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bzero((char *) cache->entries, (INITBUCKETS * sizeof(CacheEntryPtr)));
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if (!cache->entries) {
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fsfree(cache);
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return (Cache) 0;
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}
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caches[id] = cache;
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cache->elements = 0;
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cache->buckets = INITBUCKETS;
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cache->hashsize = INITHASHSIZE;
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cache->maxsize = maxsize;
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cache->cursize = 0;
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cache->nextid = id << ENTRYOFFSET;
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cache->id = id;
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num_caches++;
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return id;
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}
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static int
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hash(CacheID cid)
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{
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CachePtr cache = caches[CACHE_ID(cid)];
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switch (cache->hashsize) {
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#ifdef DEBUG /* only need this if INITHASHSIZE < 6 */
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case 2:
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return ((int) (0x03 & (cid ^ (cid >> 2) ^ (cid >> 8))));
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case 3:
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return ((int) (0x07 & (cid ^ (cid >> 3) ^ (cid >> 9))));
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case 4:
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return ((int) (0x0F & (cid ^ (cid >> 4) ^ (cid >> 10))));
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case 5:
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return ((int) (0x01F & (cid ^ (cid >> 5) ^ (cid >> 11))));
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#endif
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case 6:
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return ((int) (0x03F & (cid ^ (cid >> 6) ^ (cid >> 12))));
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case 7:
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return ((int) (0x07F & (cid ^ (cid >> 7) ^ (cid >> 13))));
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case 8:
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return ((int) (0x0FF & (cid ^ (cid >> 8) ^ (cid >> 16))));
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case 9:
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return ((int) (0x1FF & (cid ^ (cid >> 9))));
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case 10:
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return ((int) (0x3FF & (cid ^ (cid >> 10))));
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case 11:
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return ((int) (0x7FF & (cid ^ (cid >> 11))));
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}
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return -1;
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}
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static void
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rebuild_cache(CachePtr cache)
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{
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int j;
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CacheEntryPtr cp,
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next,
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**tails,
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*entries,
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**tptr,
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*cptr;
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assert(cache);
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j = 2 * cache->buckets;
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tails = (CacheEntryPtr **) ALLOCATE_LOCAL(j * sizeof(CacheEntryPtr *));
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if (!tails)
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return;
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entries = (CacheEntryPtr *) fsalloc(j * sizeof(CacheEntryPtr));
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if (!entries) {
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DEALLOCATE_LOCAL(tails);
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return;
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}
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for (cptr = entries, tptr = tails; --j >= 0; cptr++, tptr++) {
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*cptr = NullCacheEntry;
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*tptr = cptr;
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}
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cache->hashsize++;
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for (j = cache->buckets, cptr = cache->entries; --j >= 0; cptr++) {
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for (cp = *cptr; cp; cp = next) {
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next = cp->next;
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cp->next = NullCacheEntry;
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tptr = &tails[hash(cp->id)];
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**tptr = cp;
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*tptr = &cp->next;
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}
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}
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DEALLOCATE_LOCAL(tails);
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cache->buckets *= 2;
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fsfree(cache->entries);
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cache->entries = entries;
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}
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/*
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* throws out all existing entries
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*/
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void
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CacheReset(void)
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{
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CacheEntryPtr cp;
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CachePtr cache;
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int i,
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j;
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for (j = 0; j < num_caches; j++) {
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cache = caches[j];
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if (!cache)
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continue;
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for (i = 0; i < cache->buckets; i++) {
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for (cp = cache->entries[i]; cp; cp = cp->next) {
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cache->elements--;
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cache->cursize -= cp->size;
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(*cp->free_func) (cp->id, cp->data, CacheWasReset);
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fsfree(cp);
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}
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cache->entries[i] = (CacheEntryPtr) 0;
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}
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assert(cache->cursize == 0);
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}
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}
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static void
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flush_cache(CachePtr cache, unsigned long needed)
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{
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/* XXX -- try to set oldprev properly inside search loop */
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CacheEntryPtr cp,
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oldest,
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*oldprev;
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int oldbucket = -1,
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i;
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while ((cache->cursize + needed) > cache->maxsize) {
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oldest = (CacheEntryPtr) 0;
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/* find oldest */
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for (i = 0; i < cache->buckets; i++) {
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cp = cache->entries[i];
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if (!cp)
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continue;
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if (!oldest) {
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oldbucket = i;
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oldest = cp;
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}
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while (cp) {
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if (cp->timestamp < oldest->timestamp) {
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oldest = cp;
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oldbucket = i;
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}
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cp = cp->next;
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}
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}
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/* fixup list */
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oldprev = &cache->entries[oldbucket];
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cp = *oldprev;
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for (; (cp = *oldprev) != 0; oldprev = &cp->next) {
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if (cp == oldest) {
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*oldprev = oldest->next;
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break;
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}
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}
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/* clobber it */
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cache->elements--;
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cache->cursize -= oldest->size;
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(*oldest->free_func) (oldest->id, oldest->data, CacheEntryOld);
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fsfree(oldest);
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}
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}
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void
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CacheResize(Cache cid, unsigned newsize)
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{
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CachePtr cache = caches[cid];
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if (!cache)
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return;
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if (newsize < cache->maxsize) {
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/* have to toss some stuff */
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flush_cache(cache, cache->maxsize - newsize);
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}
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cache->maxsize = newsize;
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}
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CacheID
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CacheStoreMemory(
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Cache cid,
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pointer data,
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unsigned long size,
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CacheFree free_func)
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{
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CacheID id;
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CacheEntryPtr cp,
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*head;
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CachePtr cache = caches[cid];
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if (size > cache->maxsize) /* beyond cache limits */
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return (CacheID) 0;
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if ((cache->elements >= 4 * cache->buckets) &&
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(cache->hashsize < MAXHASHSIZE)) {
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rebuild_cache(cache);
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}
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id = cache->nextid++;
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if ((cache->cursize + size) > cache->maxsize) {
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flush_cache(cache, size);
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}
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head = &cache->entries[hash(id)];
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cp = (CacheEntryPtr) fsalloc(sizeof(CacheEntryRec));
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if (!cp) {
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return (CacheID) 0;
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}
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cp->next = *head;
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cp->id = id;
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cp->timestamp = GetTimeInMillis();
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cp->free_func = free_func;
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cp->size = size;
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cp->data = data;
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cache->cursize += size;
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cache->elements++;
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*head = cp;
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return id;
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}
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pointer
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CacheFetchMemory(
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CacheID cid,
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Bool update)
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{
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CachePtr cache = caches[CACHE_ID(cid)];
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CacheEntryPtr cp,
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*head;
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head = &cache->entries[hash(cid)];
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for (cp = *head; cp; cp = cp->next) {
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if (cp->id == cid) {
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if (update) {
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cp->timestamp = GetTimeInMillis();
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if (cp != *head) { /* put it in the front */
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cp->next = *head;
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*head = cp;
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}
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}
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return cp->data;
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}
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}
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return (pointer) 0;
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}
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void
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CacheFreeMemory(
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CacheID cid,
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Bool notify)
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{
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CachePtr cache = caches[CACHE_ID(cid)];
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CacheEntryPtr cp,
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*prev,
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*head;
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int *elptr;
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int elements;
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Bool found = FALSE;
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head = &cache->entries[hash(cid)];
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elptr = &cache->elements;
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prev = head;
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while ((cp = *prev) != NullCacheEntry) {
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if (cp->id == cid) {
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*prev = cp->next;
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elements = --*elptr;
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if (notify) {
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(*(cp->free_func)) (cid, cp->data, CacheEntryFreed);
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}
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cache->cursize -= cp->size;
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fsfree(cp);
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if (*elptr != elements)
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prev = head;
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found = TRUE;
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} else {
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prev = &cp->next;
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}
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}
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if (!found)
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FatalError("freeing cache entry %d which isn't there\n", cid);
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}
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/* ARGSUSED */
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void
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CacheSimpleFree(
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CacheID cid,
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pointer data,
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int reason)
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{
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fsfree(data);
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}
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