From 433f5016e22a9667b3d845a1b1dfe7c08538a5fb Mon Sep 17 00:00:00 2001
From: Philip O'Toole <philip.otoole@yahoo.com>
Date: Thu, 4 Jan 2024 20:35:25 -0500
Subject: [PATCH] Add function to test if log is "empty"

---
 log/log.go      | 16 ++++++++++++++++
 log/log_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/log/log.go b/log/log.go
index 612499e1..5e8d7781 100644
--- a/log/log.go
+++ b/log/log.go
@@ -71,6 +71,22 @@ func (l *Log) LastCommandIndex(fi, li uint64) (uint64, error) {
 	return 0, nil
 }
 
+// HasCommand returns whether the Raft log contains any Command log entries.
+func (l *Log) HasCommand() (bool, error) {
+	fi, li, err := l.Indexes()
+	if err != nil {
+		return false, err
+	}
+	if fi == 0 || li == 0 {
+		return false, nil
+	}
+	i, err := l.LastCommandIndex(fi, li)
+	if err != nil {
+		return false, err
+	}
+	return i != 0, nil
+}
+
 // SetAppliedIndex sets the AppliedIndex value.
 func (l *Log) SetAppliedIndex(index uint64) error {
 	return l.SetUint64([]byte(rqliteAppliedIndex), index)
diff --git a/log/log_test.go b/log/log_test.go
index 203f34c3..20cc09de 100644
--- a/log/log_test.go
+++ b/log/log_test.go
@@ -40,6 +40,14 @@ func Test_LogNewEmpty(t *testing.T) {
 	if lci != 0 {
 		t.Fatalf("got wrong value for last command index of not empty log: %d", lci)
 	}
+
+	f, err := l.HasCommand()
+	if err != nil {
+		t.Fatalf("failed to get has command: %s", err)
+	}
+	if f {
+		t.Fatalf("got wrong value for has command of empty log: %v", f)
+	}
 }
 
 func Test_LogNewExistNotEmpty(t *testing.T) {
@@ -91,6 +99,14 @@ func Test_LogNewExistNotEmpty(t *testing.T) {
 		t.Fatalf("got wrong value for last command index of not empty log: %d", lci)
 	}
 
+	f, err := l.HasCommand()
+	if err != nil {
+		t.Fatalf("failed to get has command: %s", err)
+	}
+	if !f {
+		t.Fatalf("got wrong value for has command of non-empty log: %v", f)
+	}
+
 	if err := l.Close(); err != nil {
 		t.Fatalf("failed to close log: %s", err)
 	}
@@ -311,6 +327,14 @@ func Test_LogDeleteAll(t *testing.T) {
 	if li != 0 {
 		t.Fatalf("got wrong value for last index of empty log: %d", li)
 	}
+
+	f, err := l.HasCommand()
+	if err != nil {
+		t.Fatalf("failed to get has command: %s", err)
+	}
+	if f {
+		t.Fatalf("got wrong value for has command of empty log: %v", f)
+	}
 }
 
 func Test_LogLastCommandIndexNotExist(t *testing.T) {