public bool IsPayback(long debtDealId)
{
DebtDealAnalysisRow ar
= this.rdbc.DebtDealsAnalysis
.Where(dda => dda.DebtDealId == debtDealId)
.First();
return(ar.IsPayback);
}
public long Add(DebtDealRow deal)
{
/*
* *** Notes on parallel execution ***
*
* If two debt deals have 4 unique involved people id-s,
* these same deals may be processed in parallel in this register
* (but may need serialization while other registers handle
* DebtDealAdded event).
*
* Need to consider validity of initialGiverDebtToTaker.
*
* Other cases:
* three unique involved id-s:
* same giver, different takers: => parallel-ok
*
* different givers, same taker: => parallel-ok
*
* two unique involved id-s:
* same giver, same taker => serialize (case a)
*
* D1.giver = D2.taker, D1.taker = D2.giver
* => serialize (case b)
*
*
* Here, parallel execution has to be serialized when register
* has not finished processing two deals which match one of these:
* a) if giver and taker are the same for two deals,
* later deal must wait till earlier one is fully processed.
* (consider small and complete pay-back immediately
* followed by a big credit - if D1 is processed after D2
* was fully processed, big credit could be considered
* as mostly a GIFT, confusing it with a payback)
*
* b) if D1.giver = D2.taker, D1.taker = D2.giver
* (consider pay and repay of the same amount -
* in case of parallel execution of both deals,
* payback could be missed and DB would get corrupt)
*/
long addedDebtDealId;
using (var transaction = this.dbc.Database.BeginTransaction()) {
this.dbc.DebtDeals.Add(deal);
this.dbc.SaveChanges(); // need deal.Id
addedDebtDealId = deal.Id;
decimal initialGiverDebtToTaker = GiverDebtToTaker();
decimal?repayGiftAmount = null;
if (initialGiverDebtToTaker > 0m)
{
repayGiftAmount
= Math.Max(0m,
deal.Amount - initialGiverDebtToTaker);
}
var analysisRow = new DebtDealAnalysisRow()
{
DebtDealId = deal.Id,
IsPayback = initialGiverDebtToTaker > 0m
};
this.dbc.DebtDealsAnalysis.Add(analysisRow);
this.dbc.SaveChanges();
DebtDealReceived?.Invoke(this,
new DebtDealReceivedEventData()
{
Deal = deal,
Analysis = analysisRow,
RepayGiftAmount = repayGiftAmount
});
transaction.Commit();
}
DebtDealAdded?.Invoke(this,
new DebtDealAddedEventData()
{
AddedDebtDealId = addedDebtDealId
});
return(addedDebtDealId);
decimal GiverDebtToTaker()
{
return(this.dbc.CurrentDebts.Where(cd =>
cd.CreditorId == deal.TakerId &&
cd.DebtorId == deal.GiverId
).Select(cd => cd.DebtTotal).FirstOrDefault());
}
}