funfs/wvdiskcache.cc

   1 #include <wvdiskcache.h>
   2
   3 #ifdef WITH_GDBM
   4
   5 #define BYTESTOKB(x) (x + ((1 << 10) - 1)) >> 10
   6
   7 WvDiskCache::WvDiskCache(WvStringParm hashpath, int megabytes)
   8     : backend(hashpath)
   9 {
  10     cur_size = 0;
  11     set_max(megabytes);
  12     head = tail = "";
  13     xcount = 0;
  14 }
  15
  16 void WvDiskCache::add(WvStringParm path, size_t size)
  17 {
  18     xcount++;
  19
  20     backend.add(path, DCFileInfo(size, head, ""), true);
  21
  22     if (!!head)
  23     {
  24         DCFileInfo fi = backend.find(head);
  25         fi.prev = path;
  26         backend.add(head, fi, true);
  27         head = path;
  28     }
  29     else
  30     {
  31         head = path;
  32     }
  33     if (!tail)
  34     {
  35         tail = path;
  36     }
  37
  38     cur_size += BYTESTOKB(size);
  39     purge();
  40 }
  41
  42 void WvDiskCache::remove(WvString path)
  43 {
  44     xcount--;
  45
  46     DCFileInfo fi = backend.find(path);
  47     backend.remove(path);
  48
  49     cur_size -= BYTESTOKB(fi.size);
  50
  51     if (path == head || path == tail)
  52     {
  53         if (path == head)
  54         {
  55             head = xcount ? fi.next : WvString("");
  56         }
  57         if (path == tail)
  58         {
  59             tail = xcount ? fi.prev : WvString("");
  60         }
  61     }
  62     else
  63     {
  64         DCFileInfo pfi = backend.find(fi.prev);
  65         pfi.prev = fi.prev;
  66         backend.add(fi.prev, pfi, true);
  67
  68         DCFileInfo nfi = backend.find(fi.prev);
  69         nfi.next = fi.next;
  70         backend.add(fi.next, nfi, true);
  71     }
  72
  73     if (callback)
  74         callback(path);
  75 }
  76
  77 void WvDiskCache::purge()
  78 {
  79     while (cur_size > max_size)
  80     {
  81         remove(tail);
  82     }
  83 }
  84
  85 void WvDiskCache::set_max(int megabytes)
  86 {
  87     max_size = megabytes * 1024;
  88     purge();
  89 }
  90
  91 #endif