From f3d7a5b8d4205057a21ddfe604e01f39cdbdc050 Mon Sep 17 00:00:00 2001
From: Philip O'Toole <philip.otoole@yahoo.com>
Date: Sat, 19 Aug 2023 12:26:07 -0400
Subject: [PATCH] More Sink tweaks

---
 snapshot/sink.go      | 11 +++++++++--
 snapshot/sink_test.go | 17 ++++++++++++++++-
 snapshot/store.go     | 21 +++++++++++++++++----
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/snapshot/sink.go b/snapshot/sink.go
index 8d8474de..2ebc8b3f 100644
--- a/snapshot/sink.go
+++ b/snapshot/sink.go
@@ -20,7 +20,8 @@ type Sink struct {
 	nextGenDir string
 	meta       *Meta
 
-	dataFD *os.File
+	nWritten int64
+	dataFD   *os.File
 
 	logger *log.Logger
 	closed bool
@@ -51,7 +52,9 @@ func (s *Sink) Open() error {
 // Write writes snapshot data to the sink. The snapshot is not in place
 // until Close is called.
 func (s *Sink) Write(p []byte) (n int, err error) {
-	return s.dataFD.Write(p)
+	n, err = s.dataFD.Write(p)
+	s.nWritten += int64(n)
+	return
 }
 
 // ID returns the ID of the snapshot being written.
@@ -76,6 +79,10 @@ func (s *Sink) Close() error {
 }
 
 func (s *Sink) processSnapshotData() error {
+	if s.nWritten == 0 {
+		return nil
+	}
+
 	if _, err := s.dataFD.Seek(0, 0); err != nil {
 		return err
 	}
diff --git a/snapshot/sink_test.go b/snapshot/sink_test.go
index 5dfdd344..09d7a13f 100644
--- a/snapshot/sink_test.go
+++ b/snapshot/sink_test.go
@@ -6,7 +6,22 @@ import (
 	"testing"
 )
 
-func Test_NewSinkOpenOK(t *testing.T) {
+func Test_NewSinkOpenCloseOK(t *testing.T) {
+	tmpDir := t.TempDir()
+	workDir := filepath.Join(tmpDir, "work")
+	mustCreateDir(workDir)
+	currGenDir := filepath.Join(tmpDir, "curr")
+	nextGenDir := filepath.Join(tmpDir, "next")
+	s := NewSink(workDir, currGenDir, nextGenDir, &Meta{})
+	if err := s.Open(); err != nil {
+		t.Fatal(err)
+	}
+	if err := s.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func Test_SinkFullSnapshot(t *testing.T) {
 	tmpDir := t.TempDir()
 	workDir := filepath.Join(tmpDir, "work")
 	mustCreateDir(workDir)
diff --git a/snapshot/store.go b/snapshot/store.go
index ef8a1feb..2fe9261f 100644
--- a/snapshot/store.go
+++ b/snapshot/store.go
@@ -75,13 +75,26 @@ func (s *Store) Create(version raft.SnapshotVersion, index, term uint64, configu
 	if err != nil {
 		return nil, err
 	}
-	snapshotName := snapshotName(term, index)
-	snapshotPath := filepath.Join(currGenDir, snapshotName+tmpSuffix)
-	if err := os.MkdirAll(snapshotPath, 0755); err != nil {
+	nextGenDir, err := s.GetNextGenerationDir()
+	if err != nil {
 		return nil, err
 	}
 
-	return nil, nil
+	meta := &Meta{
+		SnapshotMeta: raft.SnapshotMeta{
+			Index:              index,
+			Term:               term,
+			Configuration:      configuration,
+			ConfigurationIndex: configurationIndex,
+			Version:            version,
+		},
+	}
+
+	sink := NewSink(s.rootDir, currGenDir, nextGenDir, meta)
+	if err := sink.Open(); err != nil {
+		return nil, fmt.Errorf("failed to open Sink: %v", err)
+	}
+	return sink, nil
 }
 
 // List returns a list of all the snapshots in the Store.