/// <summary>
/// This method is called when clients access the Daily Exchange Rate data.
/// The Daily Exchange Rate table is unusual in that it doesn't really need to hold any data because the DataSet that the client receives
/// contains all the used rates from the GL/Gift tables whether or not those rates are in the DER table itself. Any rates in the DER table
/// that are NOT used are also returned, but, of course, because they are not used anywhere they are not very inetresting!
/// Additionally, because the GL/Gift tables do not necessarily hold a time or a time that matches the same rate in the DER table, it is possible
/// for the DER table to have a rate that is used on the date but at a different time. As a result the client sometimes does not see all rows
/// from the DER table - and so has no way of deleting them.
///
/// That is the reason why we need to automatically clean the table.
///
/// But there is some value in having some 'unused' rows that are work-in-progress. So we delete everything in the DER table that
/// applies to dates older than 30 days. In the future this might become a configurable server option.
/// </summary>
private static void DoDailyExchangeRateClean()
{
if ((DateTime.UtcNow - PreviousDailyExchangeRateAccessTime).TotalHours > 8)
{
// Nobody has opened a DailyExchangeRate screen for 8 hours
if ((DateTime.UtcNow - PreviousDailyExchangeRateCleanTime).TotalHours > 24)
{
// It is more than 24 hours since our last clean
TDBTransaction t = null;
bool bSubmissionOk = false;
DBAccess.GDBAccessObj.GetNewOrExistingAutoTransaction(IsolationLevel.Serializable, ref t, ref bSubmissionOk,
delegate
{
string logMsg = String.Empty;
int affectedRowCount = 0;
// Standard is that we delete rows applicable to dates more than 60 days old
string criticalDate = DateTime.Now.AddDays(-60).ToString("yyyy-MM-dd");
try
{
// Our deletion rule is to delete rows where
// either the effective date is too old and we have no info about creation or modification
// or the creation date is too old and we have no info about any modification
// or the modification date is too old
// These rules ensure that if rates are added to a DB that is past its last accounting period (like SA-DB)
// we can still continue to use the DER screen to add unused rates because they will have create/modify times
// that can be long past the final accounting period because we will keep
// any row that has been modified recently, whatever the effective date or creation date
// any row that was created recently but not subsequently modified, whatever the effective date
// any row where we don't have info about create/modify but where the effective date is recent
string sql = String.Format(
"DELETE FROM PUB_{0} WHERE (({1}<'{2}') and {3} is NULL and {4} is NULL) or (({3}<'{2}') and {4} is NULL) or ({4}<'{2}')",
ADailyExchangeRateTable.GetTableDBName(),
ADailyExchangeRateTable.GetDateEffectiveFromDBName(),
criticalDate,
ADailyExchangeRateTable.GetDateCreatedDBName(),
ADailyExchangeRateTable.GetDateModifiedDBName());
affectedRowCount = DBAccess.GDBAccessObj.ExecuteNonQuery(sql, t);
bSubmissionOk = true;
PreviousDailyExchangeRateCleanTime = DateTime.UtcNow;
}
catch (Exception ex)
{
logMsg = "An error occurred while trying to purge the Daily Exchange Rate table of 'aged' rows.";
logMsg += String.Format(" The exception message was: {0}", ex.Message);
}
if ((affectedRowCount > 0) && (logMsg == String.Empty))
{
logMsg =
String.Format("The Daily Exchange Rate table was purged of {0} entries applicable prior to ",
affectedRowCount) + criticalDate;
}
if (logMsg != String.Empty)
{
TLogging.Log(logMsg);
}
});
}
}
PreviousDailyExchangeRateAccessTime = DateTime.UtcNow;
}
