db: once off clean up forwarding records on db creation

db.go

@@ -96,7 +96,7 @@ type Db struct {
 	fwdHistoryLimit int
 }
 
-func NewDb(dbPath string, fwdHistoryLimit int) (*Db, error) {
+func NewDb(ctx context.Context, dbPath string, fwdHistoryLimit int) (*Db, error) {
 	const busyTimeoutMs = 5000
 
 	dsn := dbPath + fmt.Sprintf("?_pragma=busy_timeout=%d", busyTimeoutMs)
@@ -119,6 +119,12 @@ func NewDb(dbPath string, fwdHistoryLimit int) (*Db, error) {
 		fwdHistoryLimit: fwdHistoryLimit,
 	}
 
+	// Perform a once-off cleanup of the records in the db to update to a potential
+	// change in limit value.
+	if err := database.limitHTLCRecords(ctx); err != nil {
+		return nil, err
+	}
+
 	return database, nil
 }
 

db_test.go

@@ -14,7 +14,7 @@ func setupTestDb(t *testing.T, fwdingHistoryLimit int) (*Db, func()) {
 	file, err := os.CreateTemp("", "test_db_")
 	require.NoError(t, err)
 
-	db, err := NewDb(file.Name(), fwdingHistoryLimit)
+	db, err := NewDb(context.Background(), file.Name(), fwdingHistoryLimit)
 	require.NoError(t, err)
 
 	return db, func() {
@@ -129,3 +129,28 @@ func TestDbNoForwardingHistory(t *testing.T) {
 	require.NoError(t, err)
 	require.Len(t, fwds, 0)
 }
+
+func TestForwadingHistoryDelete(t *testing.T) {
+	// Create a db that will store HTLCs.
+	ctx := context.Background()
+	db, cleanup := setupTestDb(t, 5)
+	defer cleanup()
+
+	// Write a test HTLC and assert that it's stored.
+	htlc := testHtlc(1)
+	require.NoError(t, db.RecordHtlcResolution(ctx, htlc))
+
+	fwds, err := db.ListForwardingHistory(ctx, time.Time{}, time.Unix(1000000, 0))
+	require.NoError(t, err)
+	require.Len(t, fwds, 1)
+
+	// Modify the db to have a zero limit on forwarding history. We don't recreate
+	// the test db because it would re-create the file. Run limitHTLCRecords once
+	// (as we would on NewDb) to assert that we clean up our records.
+	db.fwdHistoryLimit = 0
+	require.NoError(t, db.limitHTLCRecords(ctx))
+
+	fwds, err = db.ListForwardingHistory(ctx, time.Time{}, time.Unix(1000000, 0))
+	require.NoError(t, err)
+	require.Len(t, fwds, 0)
+}

run.go

@@ -43,7 +43,7 @@ func run(c *cli.Context) error {
 	log.Infow("Opening database", "path", dbPath)
 
 	// Open database.
-	db, err := NewDb(dbPath, c.Int("fwdhistorylimit"))
+	db, err := NewDb(ctx, dbPath, c.Int("fwdhistorylimit"))
 	if err != nil {
 		return err
 	}