multi: add new config option BudgetConfig and NoDeadlineConfTarget

This commit adds a new group config `BudgetConfig` to allow users
specifying their own preference when sweeping outputs. And a new config
option `NoDeadlineConfTarget` is added in case the user wants to use a
different "lazy" conf target.

contractcourt/config.go

@@ -0,0 +1,113 @@
+package contractcourt
+
+import (
+	"fmt"
+
+	"github.com/btcsuite/btcd/btcutil"
+)
+
+const (
+	// MinBudgetValue is the minimal budget that we allow when configuring
+	// the budget used in sweeping outputs. The actual budget can be lower
+	// if the user decides to NOT set this value.
+	//
+	// NOTE: This value is chosen so the linear fee function can increase
+	// at least 1 sat/kw per block.
+	MinBudgetValue btcutil.Amount = 1008
+
+	// MinBudgetRatio is the minimal ratio that we allow when configuring
+	// the budget ratio used in sweeping outputs.
+	MinBudgetRatio = 0.001
+
+	// DefaultBudgetRatio defines a default budget ratio to be used when
+	// sweeping inputs. This is a large value, which is fine as the final
+	// fee rate is capped at the max fee rate configured.
+	DefaultBudgetRatio = 0.5
+)
+
+// BudgetConfig is a struct that holds the configuration when offering outputs
+// to the sweeper.
+//
+//nolint:lll
+type BudgetConfig struct {
+	ToLocal      btcutil.Amount `long:"tolocal" description:"The amount in satoshis to allocate as the budget to pay fees when sweeping the to_local output. If set, the budget calculated using the ratio (if set) will be capped at this value."`
+	ToLocalRatio float64        `long:"tolocalratio" description:"The ratio of the value in to_local output to allocate as the budget to pay fees when sweeping it."`
+
+	AnchorCPFP      btcutil.Amount `long:"anchorcpfp" description:"The amount in satoshis to allocate as the budget to pay fees when CPFPing a force close tx using the anchor output. If set, the budget calculated using the ratio (if set) will be capped at this value."`
+	AnchorCPFPRatio float64        `long:"anchorcpfpratio" description:"The ratio of a special value to allocate as the budget to pay fees when CPFPing a force close tx using the anchor output. The special value is the sum of all time-sensitive HTLCs on this commitment subtracted by their budgets."`
+
+	DeadlineHTLC      btcutil.Amount `long:"deadlinehtlc" description:"The amount in satoshis to allocate as the budget to pay fees when sweeping a time-sensitive (first-level) HTLC. If set, the budget calculated using the ratio (if set) will be capped at this value."`
+	DeadlineHTLCRatio float64        `long:"deadlinehtlcratio" description:"The ratio of the value in a time-sensitive (first-level) HTLC to allocate as the budget to pay fees when sweeping it."`
+
+	NoDeadlineHTLC      btcutil.Amount `long:"nodeadlinehtlc" description:"The amount in satoshis to allocate as the budget to pay fees when sweeping a non-time-sensitive (second-level) HTLC. If set, the budget calculated using the ratio (if set) will be capped at this value."`
+	NoDeadlineHTLCRatio float64        `long:"nodeadlinehtlcratio" description:"The ratio of the value in a non-time-sensitive (second-level) HTLC to allocate as the budget to pay fees when sweeping it."`
+}
+
+// Validate checks the budget configuration for any invalid values.
+func (b *BudgetConfig) Validate() error {
+	// Exit early if no budget config is set.
+	if b == nil {
+		return fmt.Errorf("no budget config set")
+	}
+
+	// Sanity check all fields.
+	if b.ToLocal != 0 && b.ToLocal < MinBudgetValue {
+		return fmt.Errorf("tolocal must be at least %v",
+			MinBudgetValue)
+	}
+	if b.ToLocalRatio != 0 && b.ToLocalRatio < MinBudgetRatio {
+		return fmt.Errorf("tolocalratio must be at least %v",
+			MinBudgetRatio)
+	}
+
+	if b.AnchorCPFP != 0 && b.AnchorCPFP < MinBudgetValue {
+		return fmt.Errorf("anchorcpfp must be at least %v",
+			MinBudgetValue)
+	}
+	if b.AnchorCPFPRatio != 0 && b.AnchorCPFPRatio < MinBudgetRatio {
+		return fmt.Errorf("anchorcpfpratio must be at least %v",
+			MinBudgetRatio)
+	}
+
+	if b.DeadlineHTLC != 0 && b.DeadlineHTLC < MinBudgetValue {
+		return fmt.Errorf("deadlinehtlc must be at least %v",
+			MinBudgetValue)
+	}
+	if b.DeadlineHTLCRatio != 0 && b.DeadlineHTLCRatio < MinBudgetRatio {
+		return fmt.Errorf("deadlinehtlcratio must be at least %v",
+			MinBudgetRatio)
+	}
+
+	if b.NoDeadlineHTLC != 0 && b.NoDeadlineHTLC < MinBudgetValue {
+		return fmt.Errorf("nodeadlinehtlc must be at least %v",
+			MinBudgetValue)
+	}
+	if b.NoDeadlineHTLCRatio != 0 &&
+		b.NoDeadlineHTLCRatio < MinBudgetRatio {
+
+		return fmt.Errorf("nodeadlinehtlcratio must be at least %v",
+			MinBudgetRatio)
+	}
+
+	return nil
+}
+
+// String returns a human-readable description of the budget configuration.
+func (b *BudgetConfig) String() string {
+	return fmt.Sprintf("tolocal=%v tolocalratio=%v anchorcpfp=%v "+
+		"anchorcpfpratio=%v deadlinehtlc=%v deadlinehtlcratio=%v "+
+		"nodeadlinehtlc=%v nodeadlinehtlcratio=%v",
+		b.ToLocal, b.ToLocalRatio, b.AnchorCPFP, b.AnchorCPFPRatio,
+		b.DeadlineHTLC, b.DeadlineHTLCRatio, b.NoDeadlineHTLC,
+		b.NoDeadlineHTLCRatio)
+}
+
+// DefaultSweeperConfig returns the default configuration for the sweeper.
+func DefaultBudgetConfig() *BudgetConfig {
+	return &BudgetConfig{
+		ToLocalRatio:        DefaultBudgetRatio,
+		AnchorCPFPRatio:     DefaultBudgetRatio,
+		DeadlineHTLCRatio:   DefaultBudgetRatio,
+		NoDeadlineHTLCRatio: DefaultBudgetRatio,
+	}
+}