/* $XConsortium: cache.c /main/11 1996/11/17 22:27:57 rws $ */ /* Copyright (c) 1994 X Consortium Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Except as contained in this notice, the name of the X Consortium shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the X Consortium. * Copyright 1990, 1991 Network Computing Devices; * Portions Copyright 1987 by Digital Equipment Corporation * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that * the above copyright notice appear in all copies and that both that * copyright notice and this permission notice appear in supporting * documentation, and that the names of Network Computing Devices, * or Digital not be used in advertising or * publicity pertaining to distribution of the software without specific, * written prior permission. Network Computing Devices, or Digital * make no representations about the * suitability of this software for any purpose. It is provided "as is" * without express or implied warranty. * * NETWORK COMPUTING DEVICES, AND DIGITAL DISCLAIM ALL WARRANTIES WITH * REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS, IN NO EVENT SHALL NETWORK COMPUTING DEVICES, OR DIGITAL BE * LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * */ #include "misc.h" #include "util.h" #include "cache.h" #define INITBUCKETS 64 #define INITHASHSIZE 6 #define MAXHASHSIZE 11 #define ENTRYOFFSET 22 #define CACHE_ENTRY_MASK 0x3FFFFF #define CACHE_ENTRY_BITS(id) ((id) & 0x1fc00000) #define CACHE_ID(id) ((int)(CACHE_ENTRY_BITS(id) >> ENTRYOFFSET)) typedef struct _cache_entry { pointer data; unsigned long timestamp; CacheID id; unsigned long size; CacheFree free_func; struct _cache_entry *next; } CacheEntryRec, *CacheEntryPtr; typedef struct _cache { Cache id; CacheEntryPtr *entries; int elements; int buckets; int hashsize; CacheID nextid; unsigned long maxsize; unsigned long cursize; } CacheRec; #define MAX_NUM_CACHES 2 static CachePtr caches[MAX_NUM_CACHES + 1]; static int num_caches = 0; static unsigned long seed = 0; /*- * Notes on cache implementation * * This is basically the X11 resource code, with some modifications * to handle aging. * * Its currently optimized for lookup & store. Flushing old stuff * is a lot slower than it should probably be, but there's tradeoffs * in tuning. */ Cache CacheInit(maxsize) unsigned long maxsize; { Cache id; CachePtr cache; cache = (CachePtr) xalloc(sizeof(CacheRec)); if (!cache) return (Cache) 0; cache->entries = (CacheEntryPtr *) xalloc(INITBUCKETS * sizeof(CacheEntryPtr)); if (!cache->entries) { xfree(cache); return (Cache) 0; } bzero((char *) cache->entries, (INITBUCKETS * sizeof(CacheEntryPtr))); id = (Cache) ++num_caches; caches[id] = cache; cache->elements = 0; cache->buckets = INITBUCKETS; cache->hashsize = INITHASHSIZE; cache->maxsize = maxsize; cache->cursize = 0; cache->nextid = id << ENTRYOFFSET; cache->id = id; return id; } void CacheFreeCache(cid) Cache cid; { CachePtr cache = caches[cid]; int i; CacheEntryPtr cp; for (i = 0; i < cache->buckets; i++) { while (cp = cache->entries[i]) { cache->entries[i] = cp->next; (*cp->free_func) (cp->id, cp->data, CacheWasReset); xfree(cp); } } caches[cid] = NULL; xfree(cache->entries); xfree(cache); } static int hash(cid, id) Cache cid; CacheID id; { CachePtr cache = caches[cid]; switch (cache->hashsize) { #if INITHASHSIZE < 6 case 2: return ((int) (0x03 & (id ^ (id >> 2) ^ (id >> 8)))); case 3: return ((int) (0x07 & (id ^ (id >> 3) ^ (id >> 9)))); case 4: return ((int) (0x0F & (id ^ (id >> 4) ^ (id >> 10)))); case 5: return ((int) (0x01F & (id ^ (id >> 5) ^ (id >> 11)))); #endif case 6: return ((int) (0x03F & (id ^ (id >> 6) ^ (id >> 12)))); case 7: return ((int) (0x07F & (id ^ (id >> 7) ^ (id >> 13)))); case 8: return ((int) (0x0FF & (id ^ (id >> 8) ^ (id >> 16)))); case 9: return ((int) (0x1FF & (id ^ (id >> 9)))); case 10: return ((int) (0x3FF & (id ^ (id >> 10)))); case 11: return ((int) (0x7FF & (id ^ (id >> 11)))); } return -1; } static void rebuild_cache(cache) CachePtr cache; { int j; CacheEntryPtr cp, next, **tails, *entries, **tptr, *cptr; j = cache->buckets << 1; tails = (CacheEntryPtr **) ALLOCATE_LOCAL(j * sizeof(CacheEntryPtr *)); if (!tails) return; entries = (CacheEntryPtr *) xalloc(j * sizeof(CacheEntryPtr)); if (!entries) { DEALLOCATE_LOCAL(tails); return; } for (cptr = entries, tptr = tails; --j >= 0; cptr++, tptr++) { *cptr = NULL; *tptr = cptr; } cache->hashsize++; for (j = cache->buckets, cptr = cache->entries; --j >= 0; cptr++) { for (cp = *cptr; cp; cp = next) { next = cp->next; cp->next = NULL; tptr = &tails[hash(cache->id, cp->id)]; **tptr = cp; *tptr = &cp->next; } } DEALLOCATE_LOCAL(tails); cache->buckets <<= 1; xfree(cache->entries); cache->entries = entries; } void CacheFreeAll() { int i; for (i = 1; i <= num_caches; i++) { if (caches[i]) CacheFreeCache(i); } num_caches = 0; } static void flush_cache(cache, needed) CachePtr cache; unsigned long needed; { CacheEntryPtr cp, *prev, oldest, *oldprev; int i; while ((cache->cursize + needed) > cache->maxsize) { oldest = NULL; /* find oldest */ for (i = 0; i < cache->buckets; i++) { for (prev = &cache->entries[i]; cp = *prev; prev = &cp->next) { if (!oldest || (cp->timestamp < oldest->timestamp)) { oldest = cp; oldprev = prev; } } } if (!oldest) break; /* clobber it */ cache->elements--; cache->cursize -= oldest->size; *oldprev = oldest->next; (*oldest->free_func) (oldest->id, oldest->data, CacheEntryOld); xfree(oldest); } } Bool CacheTrimNeeded(cid) Cache cid; { CachePtr cache = caches[cid]; return cache->cursize > cache->maxsize; } void CacheTrim(cid) Cache cid; { flush_cache(caches[cid], 0); } Bool CacheStoreMemory(cid, id, data, size, free_func, can_flush) Cache cid; CacheID id; pointer data; unsigned long size; CacheFree free_func; Bool can_flush; { CacheEntryPtr cp, *head; CachePtr cache = caches[cid]; if (can_flush && (size > cache->maxsize)) /* beyond cache limits */ return FALSE; cp = (CacheEntryPtr) xalloc(sizeof(CacheEntryRec)); if (!cp) return FALSE; if (can_flush && ((cache->cursize + size) > cache->maxsize)) flush_cache(cache, size); if ((cache->elements >= (cache->buckets << 2)) && (cache->hashsize < MAXHASHSIZE)) rebuild_cache(cache); head = &cache->entries[hash(cid, id)]; cp->next = *head; cp->id = id; cp->timestamp = ++seed; cp->free_func = free_func; cp->size = size; cp->data = data; cache->cursize += size; cache->elements++; *head = cp; return TRUE; } pointer CacheFetchMemory(cid, id, update) Cache cid; CacheID id; Bool update; { CachePtr cache = caches[cid]; CacheEntryPtr cp, *head; head = &cache->entries[hash(cid, id)]; for (cp = *head; cp; cp = cp->next) { if (cp->id == id) { if (update) cp->timestamp = ++seed; return cp->data; } } return NULL; } void CacheFreeMemory(cacheid, cid, notify) Cache cacheid; CacheID cid; Bool notify; { CachePtr cache = caches[cacheid]; CacheEntryPtr cp, *prev; for (prev = &cache->entries[hash(cacheid, cid)]; cp = *prev; prev = &cp->next) { if (cp->id == cid) { *prev = cp->next; cache->elements--; cache->cursize -= cp->size; if (notify) (*cp->free_func)(cid, cp->data, CacheEntryFreed); xfree(cp); break; } } }