// handleExecConn reads a command from the connection and executes it.
func (s *Store) handleExecConn(conn net.Conn) {
defer s.wg.Done()
// Read and execute command.
err := func() error {
// Read marker message.
b := make([]byte, 4)
if _, err := io.ReadFull(conn, b); err != nil {
return fmt.Errorf("read magic: %s", err)
} else if string(b) != ExecMagic {
return fmt.Errorf("invalid exec magic: %q", string(b))
}
// Read command size.
var sz uint64
if err := binary.Read(conn, binary.BigEndian, &sz); err != nil {
return fmt.Errorf("read size: %s", err)
}
// Read command.
buf := make([]byte, sz)
if _, err := io.ReadFull(conn, buf); err != nil {
return fmt.Errorf("read command: %s", err)
}
// Ensure command can be deserialized before applying.
if err := proto.Unmarshal(buf, &internal.Command{}); err != nil {
return fmt.Errorf("unable to unmarshal command: %s", err)
}
// Apply against the raft log.
if err := s.apply(buf); err != nil {
return fmt.Errorf("apply: %s", err)
}
return nil
}()
// Build response message.
var resp internal.Response
resp.OK = proto.Bool(err == nil)
resp.Index = proto.Uint64(s.raft.LastIndex())
if err != nil {
resp.Error = proto.String(err.Error())
}
// Encode response back to connection.
if b, err := proto.Marshal(&resp); err != nil {
panic(err)
} else if err = binary.Write(conn, binary.BigEndian, uint64(len(b))); err != nil {
s.Logger.Printf("unable to write exec response size: %s", err)
} else if _, err = conn.Write(b); err != nil {
s.Logger.Printf("unable to write exec response: %s", err)
}
conn.Close()
}
// remoteExec sends an encoded command to the remote leader.
func (s *Store) remoteExec(b []byte) error {
// Retrieve the current known leader.
leader := s.raft.Leader()
if leader == "" {
return errors.New("no leader")
}
// Create a connection to the leader.
conn, err := net.DialTimeout("tcp", leader, 10*time.Second)
if err != nil {
return err
}
defer conn.Close()
// Write a marker byte for exec messages.
_, err = conn.Write([]byte{MuxExecHeader})
if err != nil {
return err
}
// Write a marker message.
_, err = conn.Write([]byte(ExecMagic))
if err != nil {
return err
}
// Write command size & bytes.
if err := binary.Write(conn, binary.BigEndian, uint64(len(b))); err != nil {
return fmt.Errorf("write command size: %s", err)
} else if _, err := conn.Write(b); err != nil {
return fmt.Errorf("write command: %s", err)
}
// Read response bytes.
var sz uint64
if err := binary.Read(conn, binary.BigEndian, &sz); err != nil {
return fmt.Errorf("read response size: %s", err)
}
buf := make([]byte, sz)
if _, err := io.ReadFull(conn, buf); err != nil {
return fmt.Errorf("read response: %s", err)
}
// Unmarshal response.
var resp internal.Response
if err := proto.Unmarshal(buf, &resp); err != nil {
return fmt.Errorf("unmarshal response: %s", err)
} else if !resp.GetOK() {
return fmt.Errorf("exec failed: %s", resp.GetError())
}
// Wait for local FSM to sync to index.
if err := s.sync(resp.GetIndex(), 5*time.Second); err != nil {
return fmt.Errorf("sync: %s", err)
}
return nil
}