src/refresh.cc

   1
   2 /*
   3  * $Id: refresh.cc,v 1.25 1998/07/20 17:20:03 wessels Exp $
   4  *
   5  * DEBUG: section 22    Refresh Calculation
   6  * AUTHOR: Harvest Derived
   7  *
   8  * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
   9  * --------------------------------------------------------
  10  *
  11  *  Squid is the result of efforts by numerous individuals from the
  12  *  Internet community.  Development is led by Duane Wessels of the
  13  *  National Laboratory for Applied Network Research and funded by
  14  *  the National Science Foundation.
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License as published by
  18  *  the Free Software Foundation; either version 2 of the License, or
  19  *  (at your option) any later version.
  20  *
  21  *  This program is distributed in the hope that it will be useful,
  22  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  *  GNU General Public License for more details.
  25  *
  26  *  You should have received a copy of the GNU General Public License
  27  *  along with this program; if not, write to the Free Software
  28  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  29  *
  30  */
  31
  32 #ifndef USE_POSIX_REGEX
  33 #define USE_POSIX_REGEX         /* put before includes; always use POSIX */
  34 #endif
  35
  36 #include "squid.h"
  37
  38 /*
  39  * Defaults:
  40  *      MIN     NONE
  41  *      PCT     20%
  42  *      MAX     3 days
  43  */
  44 #define REFRESH_DEFAULT_MIN     (time_t)0
  45 #define REFRESH_DEFAULT_PCT     0.20
  46 #define REFRESH_DEFAULT_MAX     (time_t)259200
  47
  48 static const refresh_t * refreshLimits(const char *);
  49 static const refresh_t *refreshUncompiledPattern(const char *);
  50
  51 static const refresh_t *
  52 refreshLimits(const char *url)
  53 {
  54     const refresh_t *R;
  55     for (R = Config.Refresh; R; R = R->next) {
  56         if (!regexec(&(R->compiled_pattern), url, 0, 0, 0))
  57             return R;
  58     }
  59     return NULL;
  60 }
  61
  62 static const refresh_t *
  63 refreshUncompiledPattern(const char *pat)
  64 {
  65     const refresh_t *R;
  66     for (R = Config.Refresh; R; R = R->next) {
  67         if (0 == strcmp(R->pattern, pat))
  68             return R;
  69     }
  70     return NULL;
  71 }
  72
  73 /*
  74  * refreshCheck():
  75  *     return 1 if its time to revalidate this entry, 0 otherwise
  76  */
  77 int
  78 refreshCheck(const StoreEntry * entry, request_t * request, time_t delta)
  79 {
  80     const refresh_t *R;
  81     const char *uri;
  82     time_t min = REFRESH_DEFAULT_MIN;
  83     double pct = REFRESH_DEFAULT_PCT;
  84     time_t max = REFRESH_DEFAULT_MAX;
  85     const char *pattern = ".";
  86     time_t age;
  87     double factor;
  88     time_t check_time = squid_curtime + delta;
  89     if (entry->mem_obj)
  90         uri = entry->mem_obj->url;
  91     else
  92         uri = urlCanonical(request);
  93     debug(22, 3) ("refreshCheck: '%s'\n", uri);
  94     if (EBIT_TEST(entry->flag, ENTRY_REVALIDATE)) {
  95         debug(22, 3) ("refreshCheck: YES: Required Authorization\n");
  96         return 1;
  97     }
  98     if ((R = refreshLimits(uri))) {
  99         min = R->min;
 100         pct = R->pct;
 101         max = R->max;
 102         pattern = R->pattern;
 103     }
 104     debug(22, 3) ("refreshCheck: Matched '%s %d %d%% %d'\n",
 105         pattern, (int) min, (int) (100.0 * pct), (int) max);
 106     age = check_time - entry->timestamp;
 107     debug(22, 3) ("refreshCheck: age = %d\n", (int) age);
 108     debug(22, 3) ("\tcheck_time:\t%s\n", mkrfc1123(check_time));
 109     debug(22, 3) ("\tentry->timestamp:\t%s\n", mkrfc1123(entry->timestamp));
 110     if (request->max_age > -1) {
 111         if (age > request->max_age) {
 112             debug(22, 3) ("refreshCheck: YES: age > client-max-age\n");
 113             return 1;
 114         }
 115     }
 116     if (age <= min) {
 117         debug(22, 3) ("refreshCheck: NO: age < min\n");
 118         return 0;
 119     }
 120     if (-1 < entry->expires) {
 121         if (entry->expires <= check_time) {
 122             debug(22, 3) ("refreshCheck: YES: expires <= curtime\n");
 123             return 1;
 124         } else {
 125             debug(22, 3) ("refreshCheck: NO: expires > curtime\n");
 126             return 0;
 127         }
 128     }
 129     if (age > max) {
 130         debug(22, 3) ("refreshCheck: YES: age > max\n");
 131         return 1;
 132     }
 133     if (entry->timestamp <= entry->lastmod) {
 134         if (request->protocol != PROTO_HTTP) {
 135             debug(22, 3) ("refreshCheck: NO: non-HTTP request\n");
 136             return 0;
 137         }
 138         debug(22, 3) ("refreshCheck: YES: lastvalid <= lastmod (%d <= %d)\n",
 139             (int) entry->timestamp, (int) entry->lastmod);
 140         return 1;
 141     }
 142     factor = (double) age / (double) (entry->timestamp - entry->lastmod);
 143     debug(22, 3) ("refreshCheck: factor = %f\n", factor);
 144     if (factor < pct) {
 145         debug(22, 3) ("refreshCheck: NO: factor < pct\n");
 146         return 0;
 147     }
 148     return 1;
 149 }
 150
 151 /* returns an approximate time when refreshCheck() may return true */
 152 time_t
 153 refreshWhen(const StoreEntry * entry)
 154 {
 155     const refresh_t *R;
 156     time_t refresh_time = squid_curtime;
 157     time_t min = REFRESH_DEFAULT_MIN;
 158     time_t max = REFRESH_DEFAULT_MAX;
 159     double pct = REFRESH_DEFAULT_PCT;
 160     const char *pattern = ".";
 161     if (entry->mem_obj) {
 162         assert(entry->mem_obj->url);
 163         debug(22, 3) ("refreshWhen: key '%s'\n", storeKeyText(entry->key));
 164         debug(22, 3) ("refreshWhen: url '%s'\n", entry->mem_obj->url);
 165         if (EBIT_TEST(entry->flag, ENTRY_REVALIDATE)) {
 166             debug(22, 3) ("refreshWhen: NOW: Required Authorization\n");
 167             return refresh_time;
 168         }
 169         debug(22, 3) ("refreshWhen: entry: exp: %d, tstamp: %d, lmt: %d\n",
 170             entry->expires, entry->timestamp, entry->lastmod);
 171         R = refreshLimits(entry->mem_obj->url);
 172     } else {
 173         R = refreshUncompiledPattern(".");
 174     }
 175     if (R != NULL) {
 176         min = R->min;
 177         max = R->max;
 178         pct = R->pct;
 179         pattern = R->pattern;
 180     }
 181     debug(22, 3) ("refreshWhen: Matched '%s %d %d%% %d'\n",
 182         pattern, (int) min, (int) (100.0 * pct), (int) max);
 183     /* convert to absolute numbers */
 184     min += entry->timestamp;
 185     max += entry->timestamp;
 186     if (-1 < entry->expires) {
 187         debug(22, 3) ("refreshWhen: expires set\n");
 188         refresh_time = entry->expires;
 189     } else if (entry->timestamp <= entry->lastmod) {
 190         debug(22, 3) ("refreshWhen: lastvalid <= lastmod\n");
 191         refresh_time = squid_curtime;
 192     } else {
 193         refresh_time = (entry->timestamp - entry->lastmod) * pct + entry->timestamp;
 194         debug(22, 3) ("refreshWhen: using refresh pct\n");
 195     }
 196     /* take min/max into account, max takes priority over min */
 197     if (refresh_time < min)
 198         refresh_time = min;
 199     if (refresh_time > max)
 200         refresh_time = max;
 201     debug(22, 3) ("refreshWhen: answer: %d (in %d secs)\n",
 202         refresh_time, (int) (refresh_time - squid_curtime));
 203     return refresh_time;
 204 }
 205
 206 time_t
 207 getMaxAge(const char *url)
 208 {
 209     const refresh_t *R;
 210     debug(22, 3) ("getMaxAge: '%s'\n", url);
 211     if ((R = refreshLimits(url)))
 212         return R->max;
 213     else
 214         return REFRESH_DEFAULT_MAX;
 215 }