// If the item is not in the cache, add it.
// Evict an entry if the cache is full.
public CachedItem GetItem(int iId)
{
CachedItem item = null;
for (int i = 0; i < CachedItems.Length; i++)
{
if (CachedItems[i] != null)
{
if (CachedItems[i].iId == iId)
{
CachedItems[i].RecordAccess();
item = CachedItems[i];
break;
}
}
}
if (item == null)
{
int iItemToReplace = r.getRand(CachedItems.Length);
EvictEntry(iItemToReplace);
OnDiskItem temp = DiskItems.GetItem(iId);
item = AddEntry(iItemToReplace, temp);
iReplacedItems++;
}
return(item);
}
CachedItem AddEntry(int iIndex, OnDiskItem item)
{
CachedItem itemToCache = new CachedItem(item);
CachedItems[iIndex] = itemToCache;
CachedItems[iIndex].RecordAccess();
iCachedCount++;
return(itemToCache);
}
public string GetUserData(int iId, bool fPin)
{
string strData;
lock (this)
{
CachedItem item = GetItem(iId);
strData = item.GetUserData();
if (fPin)
{
item.PinUserData();
}
}
return(strData);
}
// I am not recording the access time when prepopulating the cache.
public void InitCache(OnDiskData diskData, int iPercent)
{
DiskItems = diskData;
int iDiskItemsCount = diskData.GetTotalItems();
int iCachedItemsCount = iDiskItemsCount * iPercent / 100;
CachedItems = new CachedItem[iCachedItemsCount];
iReplacedItems = 0;
int iAdded = 0;
while (iAdded < iCachedItemsCount)
{
OnDiskItem temp = diskData.GetItem(r.getRand(iDiskItemsCount));
CachedItem item = new CachedItem(temp);
CachedItems[iAdded] = item;
iAdded++;
}
Console.WriteLine("Cached initialized: {0} entries, heap size is {1} bytes",
iCachedItemsCount, GC.GetTotalMemory(true));
iCachedCount = iCachedItemsCount;
}