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PR F: precompute dictionaries in ViewService

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Eliminate O(N*M) linear scans in view assembly.
GetTransactionViewList / GetBookingRuleViewList: precompute
accountsById and use dictionary lookups instead of accountList.Single
per row. GetAccountViewList: group transactions by
TargetAccountId/OriginAccountId once; per-account balance is now O(k)
instead of a full scan. Fold GetBalanceInAccountCurrency and
GetCurrentBalanceInCHF into a single ComputeBalance helper so the
account-currency balance is computed once per account instead of
twice.

Defer item 19 (async I/O): after PR D each XML file is loaded at most
once per circuit, and this app is single-user local Blazor Server, so
async would be ~40 files of churn for negligible benefit.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Claudio Schaad 2026-07-02 21:00:33 +02:00
parent 2eedd2fd20
commit 5d75bbb64d
2 changed files with 55 additions and 65 deletions
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5
IMPROVEMENT_PLAN.md
View file

@ -100,5 +100,6 @@ Analysis and phased plan produced 2026-07-02. See conversation history for full
- **PR C** — Phase 2 mechanical cleanup: items 11, 13, 15, 16, 17.
- **PR D** — Phase 2 item 9: per-request unit of work / cache. Split off from PR C because it is invasive enough to warrant its own review.
- **PR E** — Phase 3 item 22: ChartService cleanup. Promoted ahead of async because it fixes an active correctness bug — `GetAccountExpensesPerMonth(accountId, year)` was mutating `ISettingsService` on the singleton to hop years, with the year parameter always hardcoded to `DateTime.Now.Year`, so the Spendings-over-time chart discarded the user's header year selection.
- **PR F** — Phase 3 items 19 + 21: async I/O across the repository stack, and precomputed dictionaries for view assembly.
- **PR G** — Phase 4 (tests) — locks in behavior for PR F.
- **PR F** — Phase 3 item 21: precomputed dictionaries in `ViewService` to eliminate O(N·M) `Single(...)` scans and per-account transaction filtering.
- **Item 19 (async I/O)** — deferred. After PR D, each XML file is loaded at most once per SignalR circuit, and this app is single-user local Blazor Server. Converting every repository/service method to async would touch ~40 files for negligible user-visible benefit and real regression risk. Revisit if the app is ever hosted for multiple concurrent users.
- **PR G** — Phase 4 (tests) — locks in behavior before further invasive changes.

101
Schaad.Accounting.Services/ViewService.cs
View file

@ -57,22 +57,43 @@ namespace Schaad.Accounting.Services
var subClassNameByNumber = subclassRepository.GetSubClassList().ToDictionary(s => s.Number, s => s.Name);
var settings = settingsService.GetSettings();
var accountList = accounts.Select(
a =>
new AccountDataset(
// Group transactions by account so per-account balance is O(k) instead of O(M).
var creditsByAccount = transactionList.GroupBy(t => t.TargetAccountId).ToDictionary(g => g.Key, g => g.ToList());
var debitsByAccount = transactionList.GroupBy(t => t.OriginAccountId).ToDictionary(g => g.Key, g => g.ToList());
var accountList = accounts.Select(a =>
{
var balance = ComputeBalance(a, creditsByAccount, debitsByAccount);
return new AccountDataset(
account: a,
balance: GetBalanceInAccountCurrency(a, transactionList),
balanceCHF: GetCurrentBalanceInCHF(a, transactionList),
balance: balance,
balanceCHF: fxService.ConvertCurrency(balance, a.Currency, "CHF", settings.FixerIoApiKey),
startBalanceCHF: fxService.ConvertCurrency(a.StartBalance, a.Currency, "CHF", settings.FixerIoApiKey),
className: subclassRepository.GetClass(a.Class),
subClassName: subClassNameByNumber[a.SubClass]
)
)
subClassName: subClassNameByNumber[a.SubClass]);
})
.ToList();
return accountList.OrderBy(a => a.Number).ToList();
}
private static decimal ComputeBalance(
Account account,
Dictionary<string, List<TransactionDataset>> creditsByAccount,
Dictionary<string, List<TransactionDataset>> debitsByAccount)
{
var balance = account.StartBalance;
if (creditsByAccount.TryGetValue(account.Id, out var credits))
{
balance += credits.Sum(t => t.GetValue(account.IsFxAccount));
}
if (debitsByAccount.TryGetValue(account.Id, out var debits))
{
balance -= debits.Sum(t => t.GetValue(account.IsFxAccount));
}
return balance;
}
public BalanceDataset GetBalanceView()
{
var accountList = GetAccountViewList();
@ -107,40 +128,20 @@ namespace Schaad.Accounting.Services
return balanceView;
}
private decimal GetBalanceInAccountCurrency(Account a, List<TransactionDataset> transactionList)
{
var balance = a.StartBalance
+ transactionList.Where(t => t.TargetAccountId == a.Id).Sum(t => t.GetValue(a.IsFxAccount))
- transactionList.Where(t => t.OriginAccountId == a.Id).Sum(t => t.GetValue(a.IsFxAccount));
return balance;
}
private decimal GetCurrentBalanceInCHF(Account a, List<TransactionDataset> transactionList)
{
var settings = settingsService.GetSettings();
var balanceInAccountCurrency = GetBalanceInAccountCurrency(a, transactionList);
var balanceInChf = fxService.ConvertCurrency(balanceInAccountCurrency, a.Currency, "CHF", settings.FixerIoApiKey);
return balanceInChf;
}
/// <summary>
/// Get transaction list with the origin and target account for each transaction
/// </summary>
public List<TransactionDataset> GetTransactionViewList()
{
var accountList = accountRepository.GetAccountList();
var accountsById = accountRepository.GetAccountList().ToDictionary(a => a.Id);
var transactionList = transactionRepository.GetTransactionList();
var transactionViewList = transactionList.Select(
t =>
return transactionList.Select(t =>
new TransactionDataset(
t,
accountList.Single(a => a.Id == t.OriginAccountId),
accountList.Single(a => a.Id == t.TargetAccountId))
)
accountsById[t.OriginAccountId],
accountsById[t.TargetAccountId]))
.ToList();
return transactionViewList;
}
/// <summary>
@ -148,53 +149,41 @@ namespace Schaad.Accounting.Services
/// </summary>
public List<TransactionDataset> GetTransactionViewList(string accountId)
{
var accountList = accountRepository.GetAccountList();
var transactionList = transactionRepository.GetTransactionList().Where(t => t.OriginAccountId == accountId || t.TargetAccountId == accountId);
var accountsById = accountRepository.GetAccountList().ToDictionary(a => a.Id);
var transactionList = transactionRepository.GetTransactionList()
.Where(t => t.OriginAccountId == accountId || t.TargetAccountId == accountId);
var transactionViewList = transactionList.Select(
t =>
return transactionList.Select(t =>
new TransactionDataset(
WithDisplaySign(t),
accountList.Single(a => a.Id == t.OriginAccountId),
accountList.Single(a => a.Id == t.TargetAccountId)
)
)
accountsById[t.OriginAccountId],
accountsById[t.TargetAccountId]))
.ToList();
return transactionViewList;
Transaction WithDisplaySign(Transaction t)
{
var account = accountList.Single(a => a.Id == t.OriginAccountId);
if (account.Class == ClassIds.Activa && accountId == t.OriginAccountId)
var originAccount = accountsById[t.OriginAccountId];
if (originAccount.Class == ClassIds.Activa && accountId == t.OriginAccountId)
{
var copy = new Transaction();
t.Copy(copy);
copy.Value *= -1;
return copy;
}
return t;
}
}
/// <summary>
/// Get booking rules with their account
/// </summary>
public List<BookingRuleDataset> GetBookingRuleViewList()
{
var accountList = accountRepository.GetAccountList();
var bookinRuleList = bookingRuleRepository.GetBookingRuleList();
var accountsById = accountRepository.GetAccountList().ToDictionary(a => a.Id);
var bookingRules = bookingRuleRepository.GetBookingRuleList();
return bookinRuleList.Select(
t =>
new BookingRuleDataset(
t,
accountList.Single(a => a.Id == t.AccountId).Name
)
)
return bookingRules.Select(t =>
new BookingRuleDataset(t, accountsById[t.AccountId].Name))
.ToList();
}