keep recent log entries after snapshot

log.go

@@ -107,6 +107,25 @@ func (l *Log) lastCommandName() string {
 	return ""
 }
 
+// Get the log entry by index
+func (l *Log) getLogEntry(index uint64) *LogEntry {
+	l.mutex.RLock()
+	defer l.mutex.RUnlock()
+
+	if index <= l.startIndex {
+		return nil
+	}
+
+	index = index - l.startIndex - 1
+
+	// copy the useful information of the log entry
+	return &LogEntry{
+		Index:   l.entries[index].Index,
+		Term:    l.entries[index].Term,
+		Command: l.entries[index].Command,
+	}
+}
+
 //--------------------------------------
 // Log Terms
 //--------------------------------------

server.go

@@ -28,7 +28,8 @@ const (
 )
 
 const (
-	MaxLogEntriesPerRequest = 200
+	MaxLogEntriesPerRequest         = 200
+	NumberOfLogEntreisAfterSnapshot = 200
 )
 
 const (
@@ -922,7 +923,14 @@ func (s *Server) takeSnapshot() error {
 
 	s.saveSnapshot()
 
-	s.log.compact(lastIndex, lastTerm)
+	// We keep some log entries after the snapshot
+	// We do not want to send the whole snapshot
+	// to the slightly slow machines
+	if lastIndex > NumberOfLogEntreisAfterSnapshot {
+		compactIndex := lastIndex - NumberOfLogEntreisAfterSnapshot
+		compactTerm := s.log.getLogEntry(compactIndex).Term
+		s.log.compact(compactIndex, compactTerm)
+	}
 
 	return nil
 }