router+switch: rename paymentID->attemptID

To distinguish the attempt's unique ID from the overall payment
identifier, we name it attemptID everywhere, and note that the
paymentHash argument won't be the actual payment hash for AMP payments.

routing/router.go

@@ -165,17 +165,21 @@ type PaymentAttemptDispatcher interface {
 	// denoted by its public key. A non-nil error is to be returned if the
 	// payment was unsuccessful.
 	SendHTLC(firstHop lnwire.ShortChannelID,
-		paymentID uint64,
+		attemptID uint64,
 		htlcAdd *lnwire.UpdateAddHTLC) error
 
 	// GetPaymentResult returns the the result of the payment attempt with
-	// the given paymentID. The method returns a channel where the payment
-	// result will be sent when available, or an error is encountered
-	// during forwarding. When a result is received on the channel, the
-	// HTLC is guaranteed to no longer be in flight. The switch shutting
-	// down is signaled by closing the channel. If the paymentID is
-	// unknown, ErrPaymentIDNotFound will be returned.
-	GetPaymentResult(paymentID uint64, paymentHash lntypes.Hash,
+	// the given attemptID. The paymentHash should be set to the payment's
+	// overall hash, or in case of AMP payments the payment's unique
+	// identifier.
+	//
+	// The method returns a channel where the payment result will be sent
+	// when available, or an error is encountered during forwarding. When a
+	// result is received on the channel, the HTLC is guaranteed to no
+	// longer be in flight.  The switch shutting down is signaled by
+	// closing the channel. If the attemptID is unknown,
+	// ErrPaymentIDNotFound will be returned.
+	GetPaymentResult(attemptID uint64, paymentHash lntypes.Hash,
 		deobfuscator htlcswitch.ErrorDecrypter) (
 		<-chan *htlcswitch.PaymentResult, error)
 
@@ -211,13 +215,13 @@ type MissionController interface {
 	// input for future probability estimates. It returns a bool indicating
 	// whether this error is a final error and no further payment attempts
 	// need to be made.
-	ReportPaymentFail(paymentID uint64, rt *route.Route,
+	ReportPaymentFail(attemptID uint64, rt *route.Route,
 		failureSourceIdx *int, failure lnwire.FailureMessage) (
 		*channeldb.FailureReason, error)
 
 	// ReportPaymentSuccess reports a successful payment to mission control as input
 	// for future probability estimates.
-	ReportPaymentSuccess(paymentID uint64, rt *route.Route) error
+	ReportPaymentSuccess(attemptID uint64, rt *route.Route) error
 
 	// GetProbability is expected to return the success probability of a
 	// payment from fromNode along edge.
@@ -2081,7 +2085,7 @@ func (r *ChannelRouter) tryApplyChannelUpdate(rt *route.Route,
 // error type, this error is either the final outcome of the payment or we need
 // to continue with an alternative route. A final outcome is indicated by a
 // non-nil return value.
-func (r *ChannelRouter) processSendError(paymentID uint64, rt *route.Route,
+func (r *ChannelRouter) processSendError(attemptID uint64, rt *route.Route,
 	sendErr error) *channeldb.FailureReason {
 
 	internalErrorReason := channeldb.FailureReasonError
@@ -2091,7 +2095,7 @@ func (r *ChannelRouter) processSendError(paymentID uint64, rt *route.Route,
 
 		// Report outcome to mission control.
 		reason, err := r.cfg.MissionControl.ReportPaymentFail(
-			paymentID, rt, srcIdx, msg,
+			attemptID, rt, srcIdx, msg,
 		)
 		if err != nil {
 			log.Errorf("Error reporting payment result to mc: %v",