watchtower+lnrpc: remove AckedUpdates from ClientSession struct

In this commit, we start making use of the new ListClientSession
functional options added in the previous commit. We use the functional
options in order to calculate the max commit heights per channel on the
construction of the tower client. We also use the options to count the
total number of acked and committed updates. With this commit, we are
also able to completely remove the AckedUpdates member of the
ClientSession since it is no longer used anywhere in the code.

watchtower/wtdb/client_db.go

@@ -1239,17 +1239,15 @@ func getClientSession(sessions, towers kvdb.RBucket, idBytes []byte,
 		return nil, err
 	}
 
-	// Fetch the acked updates for this session.
-	ackedUpdates, err := getClientSessionAcks(
-		sessionBkt, session, cfg.PerAckedUpdate,
-	)
+	// Pass the session's acked updates through the call-back if one is
+	// provided.
+	err = filterClientSessionAcks(sessionBkt, session, cfg.PerAckedUpdate)
 	if err != nil {
 		return nil, err
 	}
 
 	session.Tower = tower
 	session.CommittedUpdates = commitedUpdates
-	session.AckedUpdates = ackedUpdates
 
 	return session, nil
 }
@@ -1292,18 +1290,19 @@ func getClientSessionCommits(sessionBkt kvdb.RBucket, s *ClientSession,
 	return committedUpdates, nil
 }
 
-// getClientSessionAcks retrieves all acked updates for the session identified
-// by the serialized session id.
-func getClientSessionAcks(sessionBkt kvdb.RBucket, s *ClientSession,
-	cb PerAckedUpdateCB) (map[uint16]BackupID, error) {
+// filterClientSessionAcks retrieves all acked updates for the session
+// identified by the serialized session id and passes them to the provided
+// call back if one is provided.
+func filterClientSessionAcks(sessionBkt kvdb.RBucket, s *ClientSession,
+	cb PerAckedUpdateCB) error {
 
-	// Initialize ackedUpdates so that we can return an initialized map if
-	// no acked updates exist.
-	ackedUpdates := make(map[uint16]BackupID)
+	if cb == nil {
+		return nil
+	}
 
 	sessionAcks := sessionBkt.NestedReadBucket(cSessionAcks)
 	if sessionAcks == nil {
-		return ackedUpdates, nil
+		return nil
 	}
 
 	err := sessionAcks.ForEach(func(k, v []byte) error {
@@ -1315,19 +1314,14 @@ func getClientSessionAcks(sessionBkt kvdb.RBucket, s *ClientSession,
 			return err
 		}
 
-		ackedUpdates[seqNum] = backupID
-
-		if cb != nil {
-			cb(s, seqNum, backupID)
-		}
-
+		cb(s, seqNum, backupID)
 		return nil
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return ackedUpdates, nil
+	return nil
 }
 
 // putClientSessionBody stores the body of the ClientSession (everything but the

watchtower/wtdb/client_db_test.go

@@ -48,12 +48,12 @@ func (h *clientDBHarness) insertSession(session *wtdb.ClientSession,
 	require.ErrorIs(h.t, err, expErr)
 }
 
-func (h *clientDBHarness) listSessions(
-	id *wtdb.TowerID) map[wtdb.SessionID]*wtdb.ClientSession {
+func (h *clientDBHarness) listSessions(id *wtdb.TowerID,
+	opts ...wtdb.ClientSessionListOption) map[wtdb.SessionID]*wtdb.ClientSession {
 
 	h.t.Helper()
 
-	sessions, err := h.db.ListClientSessions(id)
+	sessions, err := h.db.ListClientSessions(id, opts...)
 	require.NoError(h.t, err, "unable to list client sessions")
 
 	return sessions
@@ -520,11 +520,7 @@ func testCommitUpdate(h *clientDBHarness) {
 	// Assert that the committed update appears in the client session's
 	// CommittedUpdates map when loaded from disk and that there are no
 	// AckedUpdates.
-	dbSession := h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, []wtdb.CommittedUpdate{
-		*update1,
-	})
-	checkAckedUpdates(h.t, dbSession, nil)
+	h.assertUpdates(session.ID, []wtdb.CommittedUpdate{*update1}, nil)
 
 	// Try to commit the same update, which should succeed due to
 	// idempotency (which is preserved when the breach hint is identical to
@@ -534,11 +530,7 @@ func testCommitUpdate(h *clientDBHarness) {
 	require.Equal(h.t, lastApplied, lastApplied2)
 
 	// Assert that the loaded ClientSession is the same as before.
-	dbSession = h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, []wtdb.CommittedUpdate{
-		*update1,
-	})
-	checkAckedUpdates(h.t, dbSession, nil)
+	h.assertUpdates(session.ID, []wtdb.CommittedUpdate{*update1}, nil)
 
 	// Generate another random update and try to commit it at the identical
 	// sequence number. Since the breach hint has changed, this should fail.
@@ -553,12 +545,10 @@ func testCommitUpdate(h *clientDBHarness) {
 
 	// Check that both updates now appear as committed on the ClientSession
 	// loaded from disk.
-	dbSession = h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, []wtdb.CommittedUpdate{
+	h.assertUpdates(session.ID, []wtdb.CommittedUpdate{
 		*update1,
 		*update2,
-	})
-	checkAckedUpdates(h.t, dbSession, nil)
+	}, nil)
 
 	// Finally, create one more random update and try to commit it at index
 	// 4, which should be rejected since 3 is the next slot the database
@@ -567,12 +557,20 @@ func testCommitUpdate(h *clientDBHarness) {
 	h.commitUpdate(&session.ID, update4, wtdb.ErrCommitUnorderedUpdate)
 
 	// Assert that the ClientSession loaded from disk remains unchanged.
-	dbSession = h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, []wtdb.CommittedUpdate{
+	h.assertUpdates(session.ID, []wtdb.CommittedUpdate{
 		*update1,
 		*update2,
-	})
-	checkAckedUpdates(h.t, dbSession, nil)
+	}, nil)
+}
+
+func perAckedUpdate(updates map[uint16]wtdb.BackupID) func(
+	_ *wtdb.ClientSession, seq uint16, id wtdb.BackupID) {
+
+	return func(_ *wtdb.ClientSession, seq uint16,
+		id wtdb.BackupID) {
+
+		updates[seq] = id
+	}
 }
 
 // testAckUpdate asserts the behavior of AckUpdate.
@@ -628,9 +626,7 @@ func testAckUpdate(h *clientDBHarness) {
 
 	// Assert that the ClientSession loaded from disk has one update in it's
 	// AckedUpdates map, and that the committed update has been removed.
-	dbSession := h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, nil)
-	checkAckedUpdates(h.t, dbSession, map[uint16]wtdb.BackupID{
+	h.assertUpdates(session.ID, nil, map[uint16]wtdb.BackupID{
 		1: update1.BackupID,
 	})
 
@@ -645,9 +641,7 @@ func testAckUpdate(h *clientDBHarness) {
 	h.ackUpdate(&session.ID, 2, 2, nil)
 
 	// Assert that both updates exist as AckedUpdates when loaded from disk.
-	dbSession = h.listSessions(nil)[session.ID]
-	checkCommittedUpdates(h.t, dbSession, nil)
-	checkAckedUpdates(h.t, dbSession, map[uint16]wtdb.BackupID{
+	h.assertUpdates(session.ID, nil, map[uint16]wtdb.BackupID{
 		1: update1.BackupID,
 		2: update2.BackupID,
 	})
@@ -663,6 +657,19 @@ func testAckUpdate(h *clientDBHarness) {
 	h.ackUpdate(&session.ID, 4, 3, wtdb.ErrUnallocatedLastApplied)
 }
 
+func (h *clientDBHarness) assertUpdates(id wtdb.SessionID,
+	expectedPending []wtdb.CommittedUpdate,
+	expectedAcked map[uint16]wtdb.BackupID) {
+
+	ackedUpdates := make(map[uint16]wtdb.BackupID)
+	_ = h.listSessions(
+		nil, wtdb.WithPerAckedUpdate(perAckedUpdate(ackedUpdates)),
+	)
+	dbSession := h.listSessions(nil)[id]
+	checkCommittedUpdates(h.t, dbSession, expectedPending)
+	checkAckedUpdates(h.t, ackedUpdates, expectedAcked)
+}
+
 // checkCommittedUpdates asserts that the CommittedUpdates on session match the
 // expUpdates provided.
 func checkCommittedUpdates(t *testing.T, session *wtdb.ClientSession,
@@ -682,7 +689,7 @@ func checkCommittedUpdates(t *testing.T, session *wtdb.ClientSession,
 
 // checkAckedUpdates asserts that the AckedUpdates on a session match the
 // expUpdates provided.
-func checkAckedUpdates(t *testing.T, session *wtdb.ClientSession,
+func checkAckedUpdates(t *testing.T, actualUpdates,
 	expUpdates map[uint16]wtdb.BackupID) {
 
 	// We promote nil expUpdates to an initialized map since the database
@@ -692,7 +699,7 @@ func checkAckedUpdates(t *testing.T, session *wtdb.ClientSession,
 		expUpdates = make(map[uint16]wtdb.BackupID)
 	}
 
-	require.Equal(t, expUpdates, session.AckedUpdates)
+	require.Equal(t, expUpdates, actualUpdates)
 }
 
 // TestClientDB asserts the behavior of a fresh client db, a reopened client db,

watchtower/wtdb/client_session.go

@@ -47,13 +47,6 @@ type ClientSession struct {
 	// insertion and retrieval.
 	CommittedUpdates []CommittedUpdate
 
-	// AckedUpdates is a map from sequence number to backup id to record
-	// which revoked states were uploaded via this session.
-	//
-	// NOTE: This map is serialized in it's own bucket, separate from the
-	// body of the ClientSession.
-	AckedUpdates map[uint16]BackupID
-
 	// Tower holds the pubkey and address of the watchtower.
 	//
 	// NOTE: This value is not serialized. It is recovered by looking up the