From b998ce11f18ab9f43575fc83d1193e9312105306 Mon Sep 17 00:00:00 2001
From: yyforyongyu <yy2452@columbia.edu>
Date: Thu, 16 Nov 2023 20:53:19 +0800
Subject: [PATCH] routing+htlcswitch: add new interface method
 `HasAttemptResult`

---
 htlcswitch/switch.go | 15 +++++++++++++++
 routing/mock_test.go | 17 +++++++++++++++++
 routing/router.go    | 10 ++++++++++
 3 files changed, 42 insertions(+)

diff --git a/htlcswitch/switch.go b/htlcswitch/switch.go
index 1ac8f93a5..0cd3d7c3d 100644
--- a/htlcswitch/switch.go
+++ b/htlcswitch/switch.go
@@ -431,6 +431,21 @@ func (s *Switch) ProcessContractResolution(msg contractcourt.ResolutionMsg) erro
 	}
 }
 
+// HasAttemptResult reads the network result store to fetch the specified
+// attempt. Returns true if the attempt result exists.
+func (s *Switch) HasAttemptResult(attemptID uint64) (bool, error) {
+	_, err := s.networkResults.getResult(attemptID)
+	if err == nil {
+		return true, nil
+	}
+
+	if !errors.Is(err, ErrPaymentIDNotFound) {
+		return false, err
+	}
+
+	return false, nil
+}
+
 // GetAttemptResult returns the result of the HTLC attempt with 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.
diff --git a/routing/mock_test.go b/routing/mock_test.go
index f712c420d..306c18210 100644
--- a/routing/mock_test.go
+++ b/routing/mock_test.go
@@ -60,6 +60,12 @@ func (m *mockPaymentAttemptDispatcherOld) SendHTLC(
 	return nil
 }
 
+func (m *mockPaymentAttemptDispatcherOld) HasAttemptResult(
+	attemptID uint64) (bool, error) {
+
+	return false, nil
+}
+
 func (m *mockPaymentAttemptDispatcherOld) GetAttemptResult(paymentID uint64,
 	_ lntypes.Hash, _ htlcswitch.ErrorDecrypter) (
 	<-chan *htlcswitch.PaymentResult, error) {
@@ -209,6 +215,10 @@ func (m *mockPayerOld) SendHTLC(_ lnwire.ShortChannelID,
 
 }
 
+func (m *mockPayerOld) HasAttemptResult(attemptID uint64) (bool, error) {
+	return false, nil
+}
+
 func (m *mockPayerOld) GetAttemptResult(paymentID uint64, _ lntypes.Hash,
 	_ htlcswitch.ErrorDecrypter) (<-chan *htlcswitch.PaymentResult, error) {
 
@@ -585,6 +595,13 @@ func (m *mockPaymentAttemptDispatcher) SendHTLC(firstHop lnwire.ShortChannelID,
 	return args.Error(0)
 }
 
+func (m *mockPaymentAttemptDispatcher) HasAttemptResult(
+	attemptID uint64) (bool, error) {
+
+	args := m.Called(attemptID)
+	return args.Bool(0), args.Error(1)
+}
+
 func (m *mockPaymentAttemptDispatcher) GetAttemptResult(attemptID uint64,
 	paymentHash lntypes.Hash, deobfuscator htlcswitch.ErrorDecrypter) (
 	<-chan *htlcswitch.PaymentResult, error) {
diff --git a/routing/router.go b/routing/router.go
index e5c55e609..c12198277 100644
--- a/routing/router.go
+++ b/routing/router.go
@@ -135,6 +135,16 @@ type PaymentAttemptDispatcher interface {
 	// NOTE: New payment attempts MUST NOT be made after the keepPids map
 	// has been created and this method has returned.
 	CleanStore(keepPids map[uint64]struct{}) error
+
+	// HasAttemptResult reads the network result store to fetch the
+	// specified attempt. Returns true if the attempt result exists.
+	//
+	// NOTE: This method is used and should only be used by the router to
+	// resume payments during startup. It can be viewed as a subset of
+	// `GetAttemptResult` in terms of its functionality, and can be removed
+	// once we move the construction of `UpdateAddHTLC` and
+	// `ErrorDecrypter` into `htlcswitch`.
+	HasAttemptResult(attemptID uint64) (bool, error)
 }
 
 // PaymentSessionSource is an interface that defines a source for the router to