cache.c

   1 /* cache.c: cache management
   2  *
   3  * Copyright (C) 2006 Lars Hjemli
   4  *
   5  * Licensed under GNU General Public License v2
   6  *   (see COPYING for full license text)
   7  */
   8
   9 #include "cgit.h"
  10
  11 const int NOLOCK = -1;
  12
  13 void cache_prepare(struct cacheitem *item)
  14 {
  15         if (!cgit_query_repo) {
  16                 item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));
  17                 item->ttl = cgit_cache_root_ttl;
  18         } else if (!cgit_query_page) {
  19                 item->name = xstrdup(fmt("%s/%s/index.html", cgit_cache_root,
  20                            cgit_query_repo));
  21                 item->ttl = cgit_cache_repo_ttl;
  22         } else {
  23                 item->name = xstrdup(fmt("%s/%s/%s/%s.html", cgit_cache_root,
  24                            cgit_query_repo, cgit_query_page,
  25                            cgit_querystring));
  26                 if (cgit_query_has_symref)
  27                         item->ttl = cgit_cache_dynamic_ttl;
  28                 else if (cgit_query_has_sha1)
  29                         item->ttl = cgit_cache_static_ttl;
  30                 else
  31                         item->ttl = cgit_cache_repo_ttl;
  32         }
  33 }
  34
  35 int cache_exist(struct cacheitem *item)
  36 {
  37         if (stat(item->name, &item->st)) {
  38                 item->st.st_mtime = 0;
  39                 return 0;
  40         }
  41         return 1;
  42 }
  43
  44 int cache_create_dirs()
  45 {
  46         char *path;
  47
  48         if (!cgit_query_repo)
  49                 return 0;
  50
  51         path = fmt("%s/%s", cgit_cache_root, cgit_query_repo);
  52         if (mkdir(path, S_IRWXU) && errno!=EEXIST)
  53                 return 0;
  54
  55         if (cgit_query_page) {
  56                 path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo,
  57                            cgit_query_page);
  58                 if (mkdir(path, S_IRWXU) && errno!=EEXIST)
  59                         return 0;
  60         }
  61         return 1;
  62 }
  63
  64 int cache_refill_overdue(const char *lockfile)
  65 {
  66         struct stat st;
  67
  68         if (stat(lockfile, &st))
  69                 return 0;
  70         else
  71                 return (time(NULL) - st.st_mtime > cgit_cache_max_create_time);
  72 }
  73
  74 int cache_lock(struct cacheitem *item)
  75 {
  76         int i = 0;
  77         char *lockfile = xstrdup(fmt("%s.lock", item->name));
  78
  79  top:
  80         if (++i > cgit_max_lock_attempts)
  81                 die("cache_lock: unable to lock %s: %s",
  82                     item->name, strerror(errno));
  83
  84         item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR);
  85
  86         if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs())
  87                 goto top;
  88
  89         if (item->fd == NOLOCK && errno == EEXIST &&
  90             cache_refill_overdue(lockfile) && !unlink(lockfile))
  91                         goto top;
  92
  93         free(lockfile);
  94         return (item->fd > 0);
  95 }
  96
  97 int cache_unlock(struct cacheitem *item)
  98 {
  99         close(item->fd);
 100         return (rename(fmt("%s.lock", item->name), item->name) == 0);
 101 }
 102
 103 int cache_cancel_lock(struct cacheitem *item)
 104 {
 105         return (unlink(fmt("%s.lock", item->name)) == 0);
 106 }
 107
 108 int cache_expired(struct cacheitem *item)
 109 {
 110         if (item->ttl < 0)
 111                 return 0;
 112         return item->st.st_mtime + item->ttl * 60 < time(NULL);
 113 }