Method executeWithLock

transaction.go:1156–1186

executeWithLock executes a function with distributed locks to ensure exclusive access to both source and destination balances. It resolves balance IDs first (handling @world indicators), then acquires locks in deterministic order to prevent deadlocks. Parameters: - ctx context.Context: The context

(ctx context.Context, transaction *model.Transaction, fn func(context.Context) (*model.Transaction, error))

// - *model.Transaction: A pointer to the Transaction model returned by the function.
// - error: An error if the locks could not be acquired or if the function execution fails.
func (l *LedgerForge) executeWithLock(ctx context.Context, transaction *model.Transaction, fn func(context.Context) (*model.Transaction, error)) (*model.Transaction, error) {
	ctx, span := tracer.Start(ctx, "ExecuteWithLock")
	defer span.End()

	// First resolve balance IDs (handle @ indicators) BEFORE acquiring locks
	// This ensures we lock on the correct balance IDs
	sourceID, destID, err := l.resolveBalanceIDs(ctx, transaction)
	if err != nil {
		span.RecordError(err)
		return nil, fmt.Errorf("failed to resolve balance IDs: %w", err)
	}

	// Update transaction with resolved IDs
	transaction.Source = sourceID
	transaction.Destination = destID

	// Acquire distributed locks for both source and destination balances
	// MultiLocker handles deduplication (if source == destination) and sorts keys lexicographically
	locker, err := l.acquireLock(ctx, sourceID, destID)
	if err != nil {
		hotpairs.RecordContention(ctx, l.hotPairs, sourceID, destID, transaction.Currency, err)
		metrics.HotpairsContentionTotal.Add(ctx, 1)
		span.RecordError(err)
		return nil, fmt.Errorf("failed to acquire lock: %w", err)
	}
	defer l.releaseLock(ctx, locker)

	// Execute the provided function with the locks held
	// The function will re-fetch balances to get fresh state after lock acquisition
	return fn(ctx)
}

// validateAndPrepareTransaction validates the transaction and prepares it by retrieving the source and destination balances.
// It starts a tracing span, validates the transaction, retrieves the balances, and updates the transaction with the balance IDs.