Increase routing probability when the swap amount is > maxPendingLocalSats (#38)

fix(liquidator.go): apply 5% backoff to max pending htlc amount to prevent swap round failures
style(liquidator_test.go): adjust spacing for better code readability

Author: Jossec101

liquidator.go

@@ -446,8 +446,9 @@ func manageChannelLiquidity(info ManageChannelLiquidityInfo) error {
 			// if the swapAmount is bigger than max pending htlc amount, set it to max pending htlc amount
 			maxPendingLocalSats := int64(channel.GetLocalConstraints().GetMaxPendingAmtMsat() / 1000)
 			if swapAmount > maxPendingLocalSats && maxPendingLocalSats > 0 {
-				swapAmount = maxPendingLocalSats
-				log.WithField("span",span).Infof("swap amount is bigger than max pending htlc amount, setting it to max pending htlc amount: %v", maxPendingLocalSats)
+				//Lets apply a backoff of 5% to the max pending htlc amount to avoid failing the swap round
+				swapAmount = int64(float64(maxPendingLocalSats) * 0.95)
+				log.WithField("span", span).Infof("swap amount is bigger than max pending htlc amount, setting it to max pending htlc amount: %v", swapAmount)
 			}
 
 			//Request nodeguard a new destination address for the reverse swap

liquidator_test.go

@@ -117,7 +117,7 @@ func Test_manageChannelLiquidity(t *testing.T) {
 			CsvDelay:          144,
 			ChanReserveSat:    250,
 			DustLimitSat:      300,
-			MaxPendingAmtMsat: 300*1000,
+			MaxPendingAmtMsat: 300 * 1000,
 			MinHtlcMsat:       350 * 1000,
 			MaxAcceptedHtlcs:  30,
 		},
@@ -146,7 +146,21 @@ func Test_manageChannelLiquidity(t *testing.T) {
 			},
 			wantErr: false,
 		},
-				{
+		{
+			name: "Manage channel liquidity test valid reverse swap bypassing max pending amt",
+			args: ManageChannelLiquidityInfo{
+				channel:             channelActive,
+				channelBalanceRatio: 0.1,
+				channelRules:        &[]nodeguard.LiquidityRule{{ChannelId: 123, NodePubkey: "", WalletId: 1, MinimumLocalBalance: 20, MinimumRemoteBalance: 80, RebalanceTarget: 40}},
+				nodeguardClient:     mockNodeGuardClient,
+				loopProvider:        mockProvider,
+				loopdMacaroon:       "0201036c6e6402f801030a10dc64226b045d25f090b114baebcbf04c1201301a160a0761646472657373120472656164120577726974651a130a04696e666f120472656164120577726974651a170a08696e766f69636573120472656164120577726974651a210a086d616361726f6f6e120867656e6572617465120472656164120577726974651a160a076d657373616765120472656164120577726974651a170a086f6666636861696e120472656164120577726974651a160a076f6e636861696e120472656164120577726974651a140a057065657273120472656164120577726974651a180a067369676e6572120867656e657261746512047265616400000620a21b8cc8c071aa5104b706b751aede972f642537c05da31450fb4b02c6da776e",
+				nodeInfo:            nodeInfo,
+				ctx:                 context.TODO(),
+			},
+			wantErr: false,
+		},
+		{
 			name: "Manage channel liquidity test valid reverse swap bypassing max pending amt",
 			args: ManageChannelLiquidityInfo{
 				channel:             channelActive,