sbin/hammer/cache.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sbin/hammer/cache.c,v 1.5 2008/05/16 18:39:03 dillon Exp $
  35  */
  36
  37 #include "hammer_util.h"
  38
  39 static int CacheUse;
  40 static int CacheMax = 16 * 1024 * 1024;
  41 static int NCache;
  42 static TAILQ_HEAD(, cache_info) CacheList = TAILQ_HEAD_INITIALIZER(CacheList);
  43
  44 void
  45 hammer_cache_set(int bytes)
  46 {
  47         CacheMax = bytes;
  48 }
  49
  50 void
  51 hammer_cache_add(struct cache_info *cache, enum cache_type type)
  52 {
  53         TAILQ_INSERT_HEAD(&CacheList, cache, entry);
  54         cache->type = type;
  55         CacheUse += HAMMER_BUFSIZE;
  56         ++NCache;
  57 }
  58
  59 void
  60 hammer_cache_del(struct cache_info *cache)
  61 {
  62         TAILQ_REMOVE(&CacheList, cache, entry);
  63         CacheUse -= HAMMER_BUFSIZE;
  64         --NCache;
  65 }
  66
  67 void
  68 hammer_cache_used(struct cache_info *cache)
  69 {
  70         TAILQ_REMOVE(&CacheList, cache, entry);
  71         TAILQ_INSERT_TAIL(&CacheList, cache, entry);
  72 }
  73
  74 void
  75 hammer_cache_flush(void)
  76 {
  77         struct cache_info *cache;
  78         struct cache_info *p = NULL;
  79         int target;
  80         int count = 0;
  81         int ncache = NCache;
  82
  83         if (CacheUse >= CacheMax) {
  84                 target = CacheMax / 2;
  85                 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) {
  86                         if (cache == p)
  87                                 break;  /* seen this before */
  88                         ++count;
  89                         if (cache->refs) {
  90                                 if (p == NULL)
  91                                         p = cache;
  92                                 hammer_cache_used(cache);
  93                                 continue;
  94                         }
  95                         if (count >= NCache) {
  96                                 CacheMax += 8 * 1024 * 1024;
  97                                 target = CacheMax / 2;
  98                                 count = 1;
  99                         }
 100                         cache->refs = 1;
 101                         cache->delete = 1;
 102                         --count;
 103
 104                         switch(cache->type) {
 105                         case ISVOLUME:
 106                                 rel_volume(cache->u.volume);
 107                                 break;
 108                         case ISBUFFER:
 109                                 rel_buffer(cache->u.buffer);
 110                                 break;
 111                         default:
 112                                 errx(1, "hammer_cache_flush: unknown type: %d",
 113                                      (int)cache->type);
 114                                 /* not reached */
 115                                 break;
 116                         }
 117                         /* structure was freed */
 118                         if (CacheUse < target)
 119                                 break;
 120                 }
 121                 if (DebugOpt > 1)
 122                         fprintf(stderr, "hammer_cache_flush: free %d/%d cache\n",
 123                                 ncache - NCache, ncache);
 124         }
 125 }
 126