From 433b4138c5c165d55c6dcf66f34797797b73bdbb Mon Sep 17 00:00:00 2001
From: Yicheng Qin <qycqycqycqycqyc@gmail.com>
Date: Wed, 29 Oct 2014 10:42:21 -0700
Subject: [PATCH] etcdserver: panic on storage error

It is a critical error to etcd, and etcd is not able to recover it now.
---
 etcdserver/server.go      | 16 +++++++++++-----
 etcdserver/server_test.go | 11 ++++++-----
 snap/snapshotter.go       |  6 +++---
 wal/wal.go                | 14 +++++++++-----
 4 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/etcdserver/server.go b/etcdserver/server.go
index f140fd202..a1f1ec4ec 100644
--- a/etcdserver/server.go
+++ b/etcdserver/server.go
@@ -89,9 +89,9 @@ type Response struct {
 type Storage interface {
 	// Save function saves ents and state to the underlying stable storage.
 	// Save MUST block until st and ents are on stable storage.
-	Save(st raftpb.HardState, ents []raftpb.Entry)
+	Save(st raftpb.HardState, ents []raftpb.Entry) error
 	// SaveSnap function saves snapshot to the underlying stable storage.
-	SaveSnap(snap raftpb.Snapshot)
+	SaveSnap(snap raftpb.Snapshot) error
 
 	// TODO: WAL should be able to control cut itself. After implement self-controled cut,
 	// remove it in this interface.
@@ -315,8 +315,12 @@ func (s *EtcdServer) run() {
 				}
 			}
 
-			s.storage.Save(rd.HardState, rd.Entries)
-			s.storage.SaveSnap(rd.Snapshot)
+			if err := s.storage.Save(rd.HardState, rd.Entries); err != nil {
+				log.Panicf("etcdserver: save state and entries error: %v", err)
+			}
+			if err := s.storage.SaveSnap(rd.Snapshot); err != nil {
+				log.Panicf("etcdserver: create snapshot error: %v", err)
+			}
 			s.send(rd.Messages)
 
 			// TODO(bmizerany): do this in the background, but take
@@ -673,7 +677,9 @@ func (s *EtcdServer) snapshot(snapi uint64, snapnodes []uint64) {
 		panic("TODO: this is bad, what do we do about it?")
 	}
 	s.node.Compact(snapi, snapnodes, d)
-	s.storage.Cut()
+	if err := s.storage.Cut(); err != nil {
+		log.Panicf("etcdserver: rotate wal file error: %v", err)
+	}
 }
 
 func GetClusterFromPeers(urls []string) (*Cluster, error) {
diff --git a/etcdserver/server_test.go b/etcdserver/server_test.go
index 6693d4f4e..d9486e384 100644
--- a/etcdserver/server_test.go
+++ b/etcdserver/server_test.go
@@ -1221,18 +1221,19 @@ type storageRecorder struct {
 	recorder
 }
 
-func (p *storageRecorder) Save(st raftpb.HardState, ents []raftpb.Entry) {
+func (p *storageRecorder) Save(st raftpb.HardState, ents []raftpb.Entry) error {
 	p.record(action{name: "Save"})
+	return nil
 }
 func (p *storageRecorder) Cut() error {
 	p.record(action{name: "Cut"})
 	return nil
 }
-func (p *storageRecorder) SaveSnap(st raftpb.Snapshot) {
-	if raft.IsEmptySnap(st) {
-		return
+func (p *storageRecorder) SaveSnap(st raftpb.Snapshot) error {
+	if !raft.IsEmptySnap(st) {
+		p.record(action{name: "SaveSnap"})
 	}
-	p.record(action{name: "SaveSnap"})
+	return nil
 }
 
 type readyNode struct {
diff --git a/snap/snapshotter.go b/snap/snapshotter.go
index 32d90a635..2aa5d4fc9 100644
--- a/snap/snapshotter.go
+++ b/snap/snapshotter.go
@@ -52,11 +52,11 @@ func New(dir string) *Snapshotter {
 	}
 }
 
-func (s *Snapshotter) SaveSnap(snapshot raftpb.Snapshot) {
+func (s *Snapshotter) SaveSnap(snapshot raftpb.Snapshot) error {
 	if raft.IsEmptySnap(snapshot) {
-		return
+		return nil
 	}
-	s.save(&snapshot)
+	return s.save(&snapshot)
 }
 
 func (s *Snapshotter) save(snapshot *raftpb.Snapshot) error {
diff --git a/wal/wal.go b/wal/wal.go
index 2655823ee..0051b8b09 100644
--- a/wal/wal.go
+++ b/wal/wal.go
@@ -273,13 +273,17 @@ func (w *WAL) SaveState(s *raftpb.HardState) error {
 	return w.encoder.encode(rec)
 }
 
-func (w *WAL) Save(st raftpb.HardState, ents []raftpb.Entry) {
+func (w *WAL) Save(st raftpb.HardState, ents []raftpb.Entry) error {
 	// TODO(xiangli): no more reference operator
-	w.SaveState(&st)
-	for i := range ents {
-		w.SaveEntry(&ents[i])
+	if err := w.SaveState(&st); err != nil {
+		return err
 	}
-	w.Sync()
+	for i := range ents {
+		if err := w.SaveEntry(&ents[i]); err != nil {
+			return err
+		}
+	}
+	return w.Sync()
 }
 
 func (w *WAL) saveCrc(prevCrc uint32) error {