Merge pull request #595 from GeorgeTsagk/easy-autoloop-feeppm-param

Easy autoloop feeppm parameter

Author: GeorgeTsagk

docs/autoloop.md

@@ -25,6 +25,10 @@ channel balance of 1M sats. Keep in mind that on first time use this will use
 the default budget parameters. If you wish to configure a custom budget you can
 find more info in the [Budget](#budget) section.
 
+In addition, if you want to control the maximum amount of fees you're willing to
+spend per swap, as a percentage of the total swap amount, you can use the
+`feepercent` parameter as explained in the [Fees](#fees) section.
+
 ## Liquidity Rules
 
 At present, autoloop can be configured to either acquire incoming liquidity 
@@ -89,10 +93,11 @@ to a percentage of the swap amount using the fee percentage parameter:
 loop setparams --feepercent={percentage of swap amount}
 ```
 
-If you would like finer grained control over swap fees, there are multiple fee
-related settings which can be used to tune the autolooper to your preference.
-The sections that follow explain these settings in detail. Note that these fees 
-are expressed on a per-swap basis, rather than as an overall budget. 
+If you are not using easyautoloop and you would like finer grained control over
+swap fees, there are multiple fee related settings which can be used to tune the
+autolooper to your preference. The sections that follow explain these settings
+in detail. Note that these fees are expressed on a per-swap basis, rather than
+as an overall budget. 
 
 ### On-Chain Fees
 When performing a successful loop out swap, the loop client needs to sweep the 

liquidity/autoloop_test.go

@@ -1419,6 +1419,33 @@ func TestEasyAutoloop(t *testing.T) {
 
 	c.easyautoloop(step, true)
 	c.stop()
+
+	// Restore the local balance to a higher value that will trigger a swap.
+	easyChannel2.LocalBalance = btcutil.Amount(95000)
+	channels = []lndclient.ChannelInfo{
+		easyChannel1, easyChannel2,
+	}
+
+	// Override the feeppm with a lower one.
+	params.FeeLimit = NewFeePortion(5)
+
+	c = newAutoloopTestCtx(t, params, channels, testRestrictions)
+	c.start()
+
+	// Even though there should be a swap dispatched in order to meet the
+	// local balance target, we expect no action as the user defined feeppm
+	// should not be sufficient for the swap to be dispatched.
+	step = &easyAutoloopStep{
+		minAmt: 1,
+		maxAmt: 50000,
+		// Since we have the exact same balance as the first step, we
+		// can reuse the quoteOut1 for the expected loop out quote.
+		quotesOut:   quotesOut1,
+		expectedOut: nil,
+	}
+
+	c.easyautoloop(step, false)
+	c.stop()
 }
 
 // existingSwapFromRequest is a helper function which returns the db

liquidity/liquidity.go

@@ -600,11 +600,21 @@ func (m *Manager) dispatchBestEasyAutoloopSwap(ctx context.Context) error {
 		return err
 	}
 
-	// Override our current parameters in order to use the const percent
-	// limit of easy-autoloop.
+	// If no fee is set, override our current parameters in order to use the
+	// default percent limit of easy-autoloop.
 	easyParams := m.params
-	easyParams.FeeLimit = &FeePortion{
-		PartsPerMillion: defaultFeePPM,
+
+	switch feeLimit := easyParams.FeeLimit.(type) {
+	case *FeePortion:
+		if feeLimit.PartsPerMillion == 0 {
+			feeLimit = &FeePortion{
+				PartsPerMillion: defaultFeePPM,
+			}
+		}
+	default:
+		feeLimit = &FeePortion{
+			PartsPerMillion: defaultFeePPM,
+		}
 	}
 
 	// Set the swap outgoing channel to the chosen channel.