/// <summary>
/// Delete the oldest items in the cache to shrink the chache by the
/// specified amount (in bytes).
/// </summary>
/// <returns>The amount of data that was actually removed</returns>
private long DeleteOldestFiles(long amount, string regionName = null)
{
// Verify that we actually need to shrink
if (amount <= 0)
{
return(0);
}
//Heap of all CacheReferences
PriortyQueue <CacheItemReference> cacheReferences = new PriortyQueue <CacheItemReference>();
//build a heap of all files in cache region
foreach (string key in GetKeys(regionName))
{
try
{
//build item reference
string cachePath = GetCachePath(key, regionName);
string policyPath = GetPolicyPath(key, regionName);
CacheItemReference ci = new CacheItemReference(key, cachePath, policyPath);
cacheReferences.Enqueue(ci);
}
catch (FileNotFoundException)
{
}
}
//remove cache items until size requirement is met
long removedBytes = 0;
while (removedBytes < amount && cacheReferences.GetSize() > 0)
{
//remove oldest item
CacheItemReference oldest = cacheReferences.Dequeue();
removedBytes += oldest.Length;
Remove(oldest.Key, regionName);
}
return(removedBytes);
}
/// <summary>
/// Loop through the cache and delete all expired files
/// </summary>
/// <returns>The amount removed (in bytes)</returns>
public long CleanCache(string regionName = null)
{
long removed = 0;
//lock down other treads from trying to shrink or clean
using (FileStream cLock = GetCleaningLock())
{
if (cLock == null)
{
return(0);
}
foreach (string key in GetKeys(regionName))
{
CacheItemPolicy policy = GetPolicy(key, regionName);
if (policy.AbsoluteExpiration < DateTime.Now)
{
try
{
string cachePath = GetCachePath(key, regionName);
string policyPath = GetPolicyPath(key, regionName);
CacheItemReference ci = new CacheItemReference(key, cachePath, policyPath);
Remove(key, regionName); // CT note: Remove will update CurrentCacheSize
removed += ci.Length;
}
catch (Exception) // skip if the file cannot be accessed
{ }
}
}
// mark that we've cleaned the cache
WriteSysFile(LastCleanedDateFile, DateTime.Now);
// unlock
cLock.Close();
}
return(removed);
}