// handleRPCConn reads a command from the connection and executes it.
func (r *rpc) handleRPCConn(conn net.Conn) {
defer conn.Close()
// RPC connections should execute on the leader. If we are not the leader,
// proxy the connection to the leader so that clients an connect to any node
// in the cluster.
r.traceCluster("rpc connection from: %v", conn.RemoteAddr())
if !r.store.IsLeader() {
r.proxyLeader(conn.(*net.TCPConn))
return
}
// Read and execute request.
typ, resp, err := func() (internal.RPCType, proto.Message, error) {
// Read request size.
var sz uint64
if err := binary.Read(conn, binary.BigEndian, &sz); err != nil {
return internal.RPCType_Error, nil, fmt.Errorf("read size: %s", err)
}
if sz == 0 {
return 0, nil, fmt.Errorf("invalid message size: %d", sz)
}
if sz >= MaxMessageSize {
return 0, nil, fmt.Errorf("max message size of %d exceeded: %d", MaxMessageSize, sz)
}
// Read request.
buf := make([]byte, sz)
if _, err := io.ReadFull(conn, buf); err != nil {
return internal.RPCType_Error, nil, fmt.Errorf("read request: %s", err)
}
// Determine the RPC type
rpcType := internal.RPCType(btou64(buf[0:8]))
buf = buf[8:]
r.traceCluster("recv %v request on: %v", rpcType, conn.RemoteAddr())
switch rpcType {
case internal.RPCType_FetchData:
var req internal.FetchDataRequest
if err := proto.Unmarshal(buf, &req); err != nil {
return internal.RPCType_Error, nil, fmt.Errorf("fetch request unmarshal: %v", err)
}
resp, err := r.handleFetchData(&req)
return rpcType, resp, err
case internal.RPCType_Join:
var req internal.JoinRequest
if err := proto.Unmarshal(buf, &req); err != nil {
return internal.RPCType_Error, nil, fmt.Errorf("join request unmarshal: %v", err)
}
resp, err := r.handleJoinRequest(&req)
return rpcType, resp, err
default:
return internal.RPCType_Error, nil, fmt.Errorf("unknown rpc type:%v", rpcType)
}
}()
// Handle unexpected RPC errors
if err != nil {
resp = &internal.ErrorResponse{
Header: &internal.ResponseHeader{
OK: proto.Bool(false),
},
}
typ = internal.RPCType_Error
}
// Set the status header and error message
if reply, ok := resp.(Reply); ok {
reply.GetHeader().OK = proto.Bool(err == nil)
if err != nil {
reply.GetHeader().Error = proto.String(err.Error())
}
}
r.sendResponse(conn, typ, resp)
}
// call sends an encoded request to the remote leader and returns
// an encoded response value.
func (r *rpc) call(dest string, req proto.Message) (proto.Message, error) {
// Determine type of request
var rpcType internal.RPCType
switch t := req.(type) {
case *internal.JoinRequest:
rpcType = internal.RPCType_Join
case *internal.FetchDataRequest:
rpcType = internal.RPCType_FetchData
default:
return nil, fmt.Errorf("unknown rpc request type: %v", t)
}
// Create a connection to the leader.
conn, err := net.DialTimeout("tcp", dest, leaderDialTimeout)
if err != nil {
return nil, err
}
defer conn.Close()
// Write a marker byte for rpc messages.
_, err = conn.Write([]byte{MuxRPCHeader})
if err != nil {
return nil, err
}
b, err := proto.Marshal(req)
if err != nil {
return nil, fmt.Errorf("rpc marshal: %v", err)
}
// Write request size & bytes.
if _, err := conn.Write(r.pack(rpcType, b)); err != nil {
return nil, fmt.Errorf("write %v rpc: %s", rpcType, err)
}
data, err := ioutil.ReadAll(conn)
if err != nil {
return nil, fmt.Errorf("read %v rpc: %v", rpcType, err)
}
// Should always have a size and type
if exp := 16; len(data) < exp {
return nil, fmt.Errorf("rpc %v failed: short read: got %v, exp %v", rpcType, len(data), exp)
}
sz := btou64(data[0:8])
if len(data[8:]) != int(sz) {
return nil, fmt.Errorf("rpc %v failed: short read: got %v, exp %v", rpcType, len(data[8:]), sz)
}
// See what response type we got back, could get a general error response
rpcType = internal.RPCType(btou64(data[8:16]))
data = data[16:]
var resp proto.Message
switch rpcType {
case internal.RPCType_Join:
resp = &internal.JoinResponse{}
case internal.RPCType_FetchData:
resp = &internal.FetchDataResponse{}
case internal.RPCType_Error:
resp = &internal.ErrorResponse{}
default:
return nil, fmt.Errorf("unknown rpc response type: %v", rpcType)
}
if err := proto.Unmarshal(data, resp); err != nil {
return nil, fmt.Errorf("rpc unmarshal: %v", err)
}
if reply, ok := resp.(Reply); ok {
if !reply.GetHeader().GetOK() {
return nil, fmt.Errorf("rpc %v failed: %s", rpcType, reply.GetHeader().GetError())
}
}
return resp, nil
}