private void sweepCacheRec(DateTime now, CacheRec rec)
{
var age = 0;
var cd = rec.m_CreateDate;
if (cd.Ticks != 0)
{
age = (int)(now - cd).TotalSeconds;
rec.m_AgeSec = age; // the Age field is needed for efficency not to compute dates on Table.Get()
}
else
{
rec.m_CreateDate = now;
return;
}
var rma = rec.m_MaxAgeSec;
var axp = rec.m_AbsoluteExpirationUTC;
if (
(age > (rma > 0 ? rma : this.m_MaxAgeSec)) ||
(axp.HasValue && now > axp.Value)
)
{
this.Remove(rec.Key); //delete expired
Interlocked.Increment(ref stat_SweepRemoveCount);
}
}
/// <summary>
/// Puts a key-identified item into this table.
/// If item with such key is already in this table then replaces it and returns false, returns true otherwise
/// </summary>
/// <param name="key">Item's unique key</param>
/// <param name="value">Item</param>
/// <param name="rec">Returns new or existing CacheRec</param>
/// <param name="maxAgeSec">For how long will the item exist in cache before it gets swept out. Pass 0 to use table-level setting (default)</param>
/// <param name="priority">Items priority relative to others in the table used during collision resolution, 0 = default</param>
/// <param name="absoluteExpirationUTC">Sets absolute UTC time stamp when item should be swept out of cache, null is default</param>
public bool Put(ulong key, object value, out CacheRec rec, int maxAgeSec = 0, int priority = 0, DateTime?absoluteExpirationUTC = null)
{
Interlocked.Increment(ref stat_PutCount);
return(_Put(key, value, out rec, maxAgeSec, priority, absoluteExpirationUTC));
}
private bool _Put(ulong key, object value, out CacheRec rec, int maxAgeSec, int priority, DateTime?absoluteExpirationUTC)
{
if (value == null)
{
throw new NFXException(StringConsts.ARGUMENT_ERROR + "Cache.TablePut(item=null)");
}
var idx = getBucketIndex(key);
var lck = m_Locks[getLockIndex(idx)];
lock (lck)
{
var bucketed = m_Buckets[idx];
if (bucketed == null)
{
rec = new CacheRec(key, value, maxAgeSec, priority, absoluteExpirationUTC);
m_Buckets[idx] = rec;
Interlocked.Increment(ref m_Count);
Interlocked.Increment(ref stat_PutInsertCount);
return(true);
}
else
{
if (bucketed is Page)
{
var page = (Page)bucketed;
lock (page)
{
var pidx = getPageIndex(key);
var existing = page.m_Records[pidx];
if (existing != null)
{
if (existing.Key == key) //reuse the CacheRec instance
{
existing.ReuseCTOR(value, maxAgeSec, priority, absoluteExpirationUTC);
Interlocked.Increment(ref stat_PutReplaceCount);
rec = existing;
return(false);
}
if (existing.m_Priority <= priority)
{
rec = new CacheRec(key, value, maxAgeSec, priority, absoluteExpirationUTC);
page.m_Records[pidx] = rec;
Interlocked.Increment(ref stat_PutCollisionCount);
return(false);
}
rec = existing;
Interlocked.Increment(ref stat_PutPriorityPreventedCollisionCount);
return(false);
}
rec = new CacheRec(key, value, maxAgeSec, priority, absoluteExpirationUTC);
page.m_Records[pidx] = rec;
Interlocked.Increment(ref stat_PutInsertCount);
}
Interlocked.Increment(ref m_Count);
return(true);
}
else
{
var existing = (CacheRec)bucketed;
if (existing.Key == key)
{
existing.ReuseCTOR(value, maxAgeSec, priority, absoluteExpirationUTC);
rec = existing;
Interlocked.Increment(ref stat_PutReplaceCount);
return(false);
}
else
{ //1st collision
var pidx = getPageIndex(existing.Key);
var npidx = getPageIndex(key);
if (npidx == pidx) //collision
{
if (existing.m_Priority <= priority)
{
rec = new CacheRec(key, value, maxAgeSec, priority, absoluteExpirationUTC);
m_Buckets[idx] = rec;
Interlocked.Increment(ref stat_PutCollisionCount);
return(false);
}
rec = existing;
Interlocked.Increment(ref stat_PutPriorityPreventedCollisionCount);
return(false);
}
// turn CacheRec into a Page
var page = new Page(m_RecPerPage);
Interlocked.Increment(ref stat_PutPageCreateCount);
Interlocked.Increment(ref m_PageCount);
page.m_Records[pidx] = existing;
rec = new CacheRec(key, value, maxAgeSec, priority, absoluteExpirationUTC);
page.m_Records[npidx] = rec;
Thread.MemoryBarrier();
m_Buckets[idx] = page; //assign page to backet AFTER page init above
Interlocked.Increment(ref m_Count);
Interlocked.Increment(ref stat_PutInsertCount);
return(true);
}
}
}
} //lock
}
internal Page(int recPerPage)
{
m_Records = new CacheRec[recPerPage];
}