From 95efaa7a0becd83f88b97d8a706e5cab34aae59c Mon Sep 17 00:00:00 2001
From: Xiang Li <xiang.li@coreos.com>
Date: Wed, 24 Jul 2013 11:03:20 -0700
Subject: [PATCH 1/2] write multiple entries with a buffered io

---
 log.go    | 42 +++++++++++++++++++++++++++++++++++++++++-
 server.go |  1 +
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/log.go b/log.go
index b6801d4f41..f20ab23a8e 100644
--- a/log.go
+++ b/log.go
@@ -464,12 +464,20 @@ func (l *Log) appendEntries(entries []*LogEntry) error {
 	l.mutex.Lock()
 	defer l.mutex.Unlock()
 
+	startPosition, _ := l.file.Seek(0, os.SEEK_CUR)
+
+	w := bufio.NewWriter(l.file)
+
+	var size int64
+	var err error
 	// Append each entry but exit if we hit an error.
 	for _, entry := range entries {
-		if err := l.appendEntry(entry); err != nil {
+		if size, err = l.appendEntryWithBuffer(entry, w, startPosition); err != nil {
 			return err
 		}
+		startPosition += size
 	}
+	w.Flush()
 
 	return nil
 }
@@ -508,6 +516,38 @@ func (l *Log) appendEntry(entry *LogEntry) error {
 	return nil
 }
 
+// appendEntry with Buffered io
+func (l *Log) appendEntryWithBuffer(entry *LogEntry, w io.Writer, startPosition int64) (int64, error) {
+	if l.file == nil {
+		return -1, errors.New("raft.Log: Log is not open")
+	}
+
+	// Make sure the term and index are greater than the previous.
+	if len(l.entries) > 0 {
+		lastEntry := l.entries[len(l.entries)-1]
+		if entry.Term < lastEntry.Term {
+			return -1, fmt.Errorf("raft.Log: Cannot append entry with earlier term (%x:%x <= %x:%x)", entry.Term, entry.Index, lastEntry.Term, lastEntry.Index)
+		} else if entry.Term == lastEntry.Term && entry.Index <= lastEntry.Index {
+			return -1, fmt.Errorf("raft.Log: Cannot append entry with earlier index in the same term (%x:%x <= %x:%x)", entry.Term, entry.Index, lastEntry.Term, lastEntry.Index)
+		}
+	}
+
+	entry.Position = startPosition
+
+	var size int
+	var err error
+	// Write to storage.
+	if size, err = entry.encode(w); err != nil {
+		return -1, err
+	}
+
+	// Append to entries list if stored on disk.
+	l.entries = append(l.entries, entry)
+	l.results = append(l.results, nil)
+
+	return int64(size), nil
+}
+
 //--------------------------------------
 // Log compaction
 //--------------------------------------
diff --git a/server.go b/server.go
index 8f9c86251b..f95d8bdaf0 100644
--- a/server.go
+++ b/server.go
@@ -724,6 +724,7 @@ func (s *Server) processCommand(command Command, e *event) {
 		e.c <- err
 		return
 	}
+
 	if err := s.log.appendEntry(entry); err != nil {
 		s.debugln("server.command.log.error:", err)
 		e.c <- err

From 085da0973e7486a0b6a9e0872bc249e539bac0c8 Mon Sep 17 00:00:00 2001
From: Xiang Li <xiang.li@coreos.com>
Date: Wed, 24 Jul 2013 11:43:33 -0700
Subject: [PATCH 2/2] refactor on buffer writes

---
 log.go | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/log.go b/log.go
index f20ab23a8e..d380c93ef3 100644
--- a/log.go
+++ b/log.go
@@ -472,9 +472,10 @@ func (l *Log) appendEntries(entries []*LogEntry) error {
 	var err error
 	// Append each entry but exit if we hit an error.
 	for _, entry := range entries {
-		if size, err = l.appendEntryWithBuffer(entry, w, startPosition); err != nil {
+		if size, err = l.writeEntry(entry, w); err != nil {
 			return err
 		}
+		entry.Position = startPosition
 		startPosition += size
 	}
 	w.Flush()
@@ -517,7 +518,7 @@ func (l *Log) appendEntry(entry *LogEntry) error {
 }
 
 // appendEntry with Buffered io
-func (l *Log) appendEntryWithBuffer(entry *LogEntry, w io.Writer, startPosition int64) (int64, error) {
+func (l *Log) writeEntry(entry *LogEntry, w io.Writer) (int64, error) {
 	if l.file == nil {
 		return -1, errors.New("raft.Log: Log is not open")
 	}
@@ -532,12 +533,9 @@ func (l *Log) appendEntryWithBuffer(entry *LogEntry, w io.Writer, startPosition
 		}
 	}
 
-	entry.Position = startPosition
-
-	var size int
-	var err error
 	// Write to storage.
-	if size, err = entry.encode(w); err != nil {
+	size, err := entry.encode(w)
+	if err != nil {
 		return -1, err
 	}