From 81e6df0d575f95276377d66a85527ee31f66d541 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Wed, 16 Nov 2016 01:15:39 -0500
Subject: [PATCH] cswal: write #HEIGHT:1 for empty wal

---
 consensus/wal.go | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/consensus/wal.go b/consensus/wal.go
index 467baa037..2bd24c72d 100644
--- a/consensus/wal.go
+++ b/consensus/wal.go
@@ -33,7 +33,6 @@ var _ = wire.RegisterInterface(
 // Can be used for crash-recovery and deterministic replay
 // TODO: currently the wal is overwritten during replay catchup
 //   give it a mode so it's either reading or appending - must read to end to start appending again
-// TODO: #HEIGHT 1 is never printed ...
 type WAL struct {
 	BaseService
 
@@ -55,7 +54,19 @@ func NewWAL(walDir string, light bool) (*WAL, error) {
 		light: light,
 	}
 	wal.BaseService = *NewBaseService(log, "WAL", wal)
-	return wal, nil
+	_, err = wal.Start()
+	return wal, err
+}
+
+func (wal *WAL) OnStart() error {
+	wal.BaseService.OnStart()
+	size, err := wal.group.Head.Size()
+	if err != nil {
+		return err
+	} else if size == 0 {
+		wal.writeHeight(1)
+	}
+	return nil
 }
 
 func (wal *WAL) OnStop() {
@@ -81,7 +92,7 @@ func (wal *WAL) Save(wmsg WALMessage) {
 	// Write #HEIGHT: XYZ if new height
 	if edrs, ok := wmsg.(types.EventDataRoundState); ok {
 		if edrs.Step == RoundStepNewHeight.String() {
-			wal.group.WriteLine(Fmt("#HEIGHT: %v", edrs.Height))
+			wal.writeHeight(edrs.Height)
 		}
 	}
 	// Write the wal message
@@ -91,3 +102,7 @@ func (wal *WAL) Save(wmsg WALMessage) {
 		PanicQ(Fmt("Error writing msg to consensus wal. Error: %v \n\nMessage: %v", err, wmsg))
 	}
 }
+
+func (wal *WAL) writeHeight(height int) {
+	wal.group.WriteLine(Fmt("#HEIGHT: %v", height))
+}