private bool CheckTriggerRecordsForUpdate(string tablename, string updateflag)
{
if (updateflag.HasSomething() && updateflag.Contains(RefreshKeyword))
{
using (var db = new MarketContext(ConnectionStr))
{
var entry = db.ProcGetCacheUpdateTime(tablename).FirstOrDefault();
//now check if we have something in cache records
if (entry != null)
{
DateTime lastupdate = DateTime.Parse(updateflag.Replace(RefreshKeyword, ""));
//compare
if (lastupdate >= entry.UpdateTime)
{
//dont need update. our cache is better than what triggered in db.
return false;
}
}
else
{
return false; //no need to refresh that. we dont have any entry in cache table
}
}
}
return true;
}
/// <summary>
/// we will cache market codes
/// cache will be updated if something changes from website or db.
/// Db triggers handle changes and record in a simple table. We check that
/// every time,so we can skip expensive queries and only check audit tables to refresh cache.
/// </summary>
/// <returns></returns>
private string[] GetCacheMarketCodes(int companyid)
{
//keep update flag for mailcodes. we will update this when some change happens at db
string updateflag = (string)HttpContext.Cache["MailCodesUpdate" + companyid];
bool needsupdate = CheckTriggerRecordsForUpdate("MarketEvents", updateflag);
Logger.Trace("Cache check:" +
HttpContext.Cache["MailCodesUpdate" + companyid]);
if (needsupdate ||
HttpContext.Cache["MailCodes" + companyid] == null)
{
using (var db = new MarketContext(ConnectionStr))
{
//make call to db to pget items
var listitems =
(from x in db.MarketEvents orderby x.Campaign select x.Campaign).Distinct().OrderBy(a => a).
ToArray();
//Add item to cache with expiration time, sliding, priority and callback if needed
HttpContext.Cache["MailCodes" + companyid] = listitems;
//log this for tracing
Logger.Trace("Cache will update for MailCodes:" +
HttpContext.Cache["MailCodesUpdate" + companyid]);
//set as refreshed to track when we refreshed this
HttpContext.Cache["MailCodesUpdate" + companyid] = RefreshKeyword + DateTime.UtcNow.ToString();
}
}
return HttpContext.Cache["MailCodes" + companyid] as string[];
}