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 <sys/types.h>
  38 #include <assert.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <stdarg.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #include <err.h>
  45 #include <fcntl.h>
  46 #include "hammer_util.h"
  47
  48 static int CacheUse;
  49 static int CacheMax = 16 * 1024 * 1024;
  50 static int NCache;
  51 static TAILQ_HEAD(, cache_info) CacheList = TAILQ_HEAD_INITIALIZER(CacheList);
  52
  53 void
  54 hammer_cache_set(int bytes)
  55 {
  56         CacheMax = bytes;
  57 }
  58
  59 void
  60 hammer_cache_add(struct cache_info *cache, enum cache_type type)
  61 {
  62         TAILQ_INSERT_HEAD(&CacheList, cache, entry);
  63         cache->type = type;
  64         CacheUse += HAMMER_BUFSIZE;
  65         ++NCache;
  66 }
  67
  68 void
  69 hammer_cache_del(struct cache_info *cache)
  70 {
  71         TAILQ_REMOVE(&CacheList, cache, entry);
  72         CacheUse -= HAMMER_BUFSIZE;
  73         --NCache;
  74 }
  75
  76 void
  77 hammer_cache_used(struct cache_info *cache)
  78 {
  79         TAILQ_REMOVE(&CacheList, cache, entry);
  80         TAILQ_INSERT_TAIL(&CacheList, cache, entry);
  81 }
  82
  83 void
  84 hammer_cache_flush(void)
  85 {
  86         struct cache_info *cache;
  87         struct cache_info *p = NULL;
  88         int target;
  89         int count = 0;
  90         int ncache = NCache;
  91
  92         if (CacheUse >= CacheMax) {
  93                 target = CacheMax / 2;
  94                 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) {
  95                         if (cache == p)
  96                                 break;  /* seen this before */
  97                         ++count;
  98                         if (cache->refs) {
  99                                 if (p == NULL)
 100                                         p = cache;
 101                                 hammer_cache_used(cache);
 102                                 continue;
 103                         }
 104                         if (count >= NCache) {
 105                                 CacheMax += 8 * 1024 * 1024;
 106                                 target = CacheMax / 2;
 107                                 count = 1;
 108                         }
 109                         cache->refs = 1;
 110                         cache->delete = 1;
 111                         --count;
 112
 113                         switch(cache->type) {
 114                         case ISVOLUME:
 115                                 rel_volume(cache->u.volume);
 116                                 break;
 117                         case ISBUFFER:
 118                                 rel_buffer(cache->u.buffer);
 119                                 break;
 120                         default:
 121                                 errx(1, "hammer_cache_flush: unknown type: %d",
 122                                      (int)cache->type);
 123                                 /* not reached */
 124                                 break;
 125                         }
 126                         /* structure was freed */
 127                         if (CacheUse < target)
 128                                 break;
 129                 }
 130                 if (DebugOpt)
 131                         fprintf(stderr, "hammer_cache_flush: free %d/%d cache\n",
 132                                 ncache - NCache, ncache);
 133         }
 134 }
 135