Refactor topic/message format.
Ben Johnson
parent
14fd40cdb5
commit
7dbfc11b85
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@ -3,9 +3,10 @@ Broker
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## Uncompleted
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- [ ] HTTP Handler
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- [ ] Broker client
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- [ ] Cluster configuration integration
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- [ ] Broker FSM snapshotting
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- [ ] HTTP Handler
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- [ ] Replica heartbeats
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- [ ] Segment topic files.
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- [ ] Topic truncation
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@ -23,3 +24,4 @@ Broker
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- [x] Config topic
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- [x] Stream topic from index
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- [x] Test coverage
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- [x] Move topic id into message.
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@ -118,14 +118,18 @@ func (b *Broker) Publish(topic string, m *Message) (uint64, error) {
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return 0, ErrTopicNotFound
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}
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return b.log.Apply(encodeTopicMessage(t.id, m))
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// Attach topic id to the message and encode.
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m.TopicID = t.id
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buf, _ := m.MarshalBinary()
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return b.log.Apply(buf)
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}
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// publishConfig writes a configuration change to the config topic.
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// This always waits until the change is applied to the log.
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func (b *Broker) publishConfig(m *Message) error {
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// Encode topic, type, and data together.
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buf := encodeTopicMessage(configTopicID, m)
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m.TopicID = configTopicID
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buf, _ := m.MarshalBinary()
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// Apply to the raft log.
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index, err := b.log.Apply(buf)
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@ -393,13 +397,17 @@ func (fsm *brokerFSM) Apply(e *raft.LogEntry) error {
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return nil
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}
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// Decode the topic message from the raft log.
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topicID, m := decodeTopicMessage(e.Data)
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// Decode the message from the raft log.
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m := &Message{}
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err := m.UnmarshalBinary(e.Data)
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assert(err == nil, "message unmarshal: %s", err)
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// Add the raft index to the message.
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m.Index = e.Index
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// Find topic by id. Ignore topic if it doesn't exist.
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t := b.topics[topicID]
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assert(t != nil, "topic not found: %d", topicID)
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t := b.topics[m.TopicID]
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assert(t != nil, "topic not found: %d", m.TopicID)
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// Update the broker configuration.
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switch m.Type {
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@ -470,25 +478,6 @@ func (fsm *brokerFSM) Restore(r io.Reader) error {
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return nil
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}
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// encodes a topic id and message together for the raft log.
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func encodeTopicMessage(topicID uint32, m *Message) []byte {
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b := make([]byte, 4+2+len(m.Data))
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binary.BigEndian.PutUint32(b, topicID)
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binary.BigEndian.PutUint16(b[4:6], uint16(m.Type))
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copy(b[6:], m.Data)
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return b
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}
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// decodes a topic id and message together from the raft log.
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func decodeTopicMessage(b []byte) (topicID uint32, m *Message) {
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topicID = binary.BigEndian.Uint32(b[0:4])
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m = &Message{
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Type: MessageType(binary.BigEndian.Uint16(b[4:6])),
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Data: b[6:],
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}
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return
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}
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// topic represents a single named queue of messages.
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// Each topic is identified by a unique path.
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type topic struct {
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@ -585,7 +574,7 @@ func (t *topic) encode(m *Message) error {
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// Encode message.
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b := make([]byte, messageHeaderSize+len(m.Data))
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copy(b, m.header())
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copy(b, m.marshalHeader())
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copy(b[messageHeaderSize:], m.Data)
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// Write to topic file.
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@ -762,18 +751,19 @@ const (
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)
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// The size of the encoded message header, in bytes.
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const messageHeaderSize = 2 + 8 + 4
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const messageHeaderSize = 2 + 4 + 8 + 4
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// Message represents a single item in a topic.
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type Message struct {
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Type MessageType
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TopicID uint32
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Index uint64
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Data []byte
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}
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// WriteTo encodes and writes the message to a writer. Implements io.WriterTo.
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func (m *Message) WriteTo(w io.Writer) (n int, err error) {
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if n, err := w.Write(m.header()); err != nil {
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if n, err := w.Write(m.marshalHeader()); err != nil {
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return n, err
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}
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if n, err := w.Write(m.Data); err != nil {
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@ -782,15 +772,45 @@ func (m *Message) WriteTo(w io.Writer) (n int, err error) {
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return messageHeaderSize + len(m.Data), nil
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}
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// header returns a byte slice with the message header.
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func (m *Message) header() []byte {
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// MarshalBinary returns a binary representation of the message.
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// This implements encoding.BinaryMarshaler. An error cannot be returned.
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func (m *Message) MarshalBinary() ([]byte, error) {
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b := make([]byte, messageHeaderSize+len(m.Data))
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copy(b, m.marshalHeader())
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copy(b[messageHeaderSize:], m.Data)
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return b, nil
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}
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// UnmarshalBinary reads a message from a binary encoded slice.
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// This implements encoding.BinaryUnmarshaler.
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func (m *Message) UnmarshalBinary(b []byte) error {
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m.unmarshalHeader(b)
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if len(b[messageHeaderSize:]) < len(m.Data) {
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return fmt.Errorf("message data too short: %d < %d", len(b[messageHeaderSize:]), len(m.Data))
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}
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copy(m.Data, b[messageHeaderSize:])
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return nil
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}
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// marshalHeader returns a byte slice with the message header.
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func (m *Message) marshalHeader() []byte {
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b := make([]byte, messageHeaderSize)
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binary.BigEndian.PutUint16(b[0:2], uint16(m.Type))
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binary.BigEndian.PutUint64(b[2:10], m.Index)
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binary.BigEndian.PutUint32(b[10:14], uint32(len(m.Data)))
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binary.BigEndian.PutUint32(b[2:6], m.TopicID)
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binary.BigEndian.PutUint64(b[6:14], m.Index)
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binary.BigEndian.PutUint32(b[14:18], uint32(len(m.Data)))
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return b
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}
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// unmarshalHeader reads message header data from binary encoded slice.
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// The data field is appropriately sized but is not filled.
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func (m *Message) unmarshalHeader(b []byte) {
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m.Type = MessageType(binary.BigEndian.Uint16(b[0:2]))
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m.TopicID = binary.BigEndian.Uint32(b[2:6])
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m.Index = binary.BigEndian.Uint64(b[6:14])
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m.Data = make([]byte, binary.BigEndian.Uint32(b[14:18]))
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}
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// MessageDecoder decodes messages from a reader.
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type MessageDecoder struct {
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r io.Reader
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@ -803,17 +823,15 @@ func NewMessageDecoder(r io.Reader) *MessageDecoder {
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// Decode reads a message from the decoder's reader.
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func (dec *MessageDecoder) Decode(m *Message) error {
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// Read header bytes.
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var b [messageHeaderSize]byte
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if _, err := io.ReadFull(dec.r, b[:]); err != nil {
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return err
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}
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m.Type = MessageType(binary.BigEndian.Uint16(b[0:2]))
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m.Index = binary.BigEndian.Uint64(b[2:10])
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m.Data = make([]byte, binary.BigEndian.Uint32(b[10:14]))
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m.unmarshalHeader(b[:])
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// Read data.
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if n, err := io.ReadFull(dec.r, m.Data); err != nil {
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warn("io.2", n, len(m.Data), err)
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if _, err := io.ReadFull(dec.r, m.Data); err != nil {
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return err
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}
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@ -94,7 +94,7 @@ func TestBroker_Publish(t *testing.T) {
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// Read out the published message.
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if err := dec.Decode(&m); err != nil {
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t.Fatalf("decode: %s", err)
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} else if !reflect.DeepEqual(&m, &broker.Message{Type: 100, Index: 5, Data: []byte("0000")}) {
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} else if !reflect.DeepEqual(&m, &broker.Message{Type: 100, TopicID: 1, Index: 5, Data: []byte("0000")}) {
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t.Fatalf("unexpected message: %#v", &m)
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}
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@ -299,9 +299,3 @@ func tempfile() string {
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func warn(v ...interface{}) { fmt.Fprintln(os.Stderr, v...) }
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func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr, msg+"\n", v...) }
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func ok(err error) {
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if err != nil {
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panic("unexpected error")
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}
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}
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@ -9,8 +9,9 @@ import (
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"time"
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)
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// ReconnectTimeout is the time to wait between stream disconnects before retrying.
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const ReconnectTimeout = 100 * time.Millisecond
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// DefaultReconnectTimeout is the default time to wait between when a broker
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// stream disconnects and another connection is retried.
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const DefaultReconnectTimeout = 100 * time.Millisecond
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// Client represents a client for the broker's HTTP API.
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// Once opened, the client will stream down all messages that
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@ -20,18 +21,22 @@ type Client struct {
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urls []*url.URL // list of URLs for all known brokers.
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opened bool
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done chan struct{} // disconnection notification
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done chan chan struct{} // disconnection notification
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// Channel streams messages from the broker.
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// Messages can be duplicated so it is important to check the index
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// of the incoming message index to make sure it has not been processed.
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C chan *Message
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// The amount of time to wait before reconnecting to a broker stream.
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ReconnectTimeout time.Duration
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}
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// NewClient returns a new instance of Client.
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func NewClient(name string) *Client {
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return &Client{
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name: name,
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ReconnectTimeout: DefaultReconnectTimeout,
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}
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}
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@ -65,7 +70,7 @@ func (c *Client) Open(urls []*url.URL) error {
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c.C = make(chan *Message, 0)
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// Open the streamer.
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c.done = make(chan struct{})
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c.done = make(chan chan struct{})
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go c.streamer(c.done)
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// Set open flag.
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@ -84,14 +89,16 @@ func (c *Client) Close() error {
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return ErrClientClosed
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}
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// Shutdown streamer.
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ch := make(chan struct{})
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c.done <- ch
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<-ch
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c.done = nil
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// Close message stream.
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close(c.C)
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c.C = nil
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// Shutdown streamer.
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close(c.done)
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c.done = nil
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// Unset open flag.
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c.opened = false
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@ -99,11 +106,12 @@ func (c *Client) Close() error {
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}
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// streamer connects to a broker server and streams the replica's messages.
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func (c *Client) streamer(done chan struct{}) {
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func (c *Client) streamer(done chan chan struct{}) {
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for {
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// Check for the client disconnection.
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select {
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case <-done:
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case ch := <-done:
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close(ch)
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return
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default:
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}
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@ -123,38 +131,57 @@ func (c *Client) streamer(done chan struct{}) {
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}
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// streamFromURL connects to a broker server and streams the replica's messages.
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func (c *Client) streamFromURL(u *url.URL, done chan struct{}) error {
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func (c *Client) streamFromURL(u *url.URL, done chan chan struct{}) error {
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// Set the replica name on the URL and open the stream.
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u.RawQuery = url.Values{"name": {c.name}}.Encode()
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resp, err := http.Get(u.String())
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if err != nil {
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time.Sleep(ReconnectTimeout)
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time.Sleep(c.ReconnectTimeout)
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return nil
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}
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defer func() { _ = resp.Body.Close() }()
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// Ensure that we received a 200 OK from the server before streaming.
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if resp.StatusCode != http.StatusOK {
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warn("status:", resp.StatusCode)
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time.Sleep(c.ReconnectTimeout)
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return nil
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}
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// Continuously decode messages from request body.
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// Continuously decode messages from request body in a separate goroutine.
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errNotify := make(chan error, 0)
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go func() {
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dec := NewMessageDecoder(resp.Body)
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for {
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// Decode message from the stream.
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m := &Message{}
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if err := dec.Decode(m); err != nil {
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return err
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errNotify <- err
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return
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}
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// Send message to channel.
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// Write message to streaming channel.
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c.C <- m
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}
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}()
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// Check for notification of disconnect.
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// Check for the client disconnect or error from the stream.
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select {
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case <-done:
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return errDone
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case ch := <-done:
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// Close body.
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resp.Body.Close()
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// Clear message buffer.
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select {
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case <-c.C:
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default:
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}
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// Notify the close function and return marker error.
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close(ch)
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return errDone
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case err := <-errNotify:
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return err
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}
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}
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@ -3,18 +3,27 @@ package broker_test
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import (
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"net/url"
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"testing"
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"time"
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"github.com/influxdb/influxdb/broker"
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)
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// Ensure the client name can be retrieved.
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func TestClient_Name(t *testing.T) {
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c := NewClient("node0")
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defer c.Close()
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if name := c.Name(); name != "node0" {
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t.Fatalf("unexpected name: %s", name)
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}
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}
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// Ensure that a client can open a connect to the broker.
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func TestClient_Open(t *testing.T) {
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c := NewClient("node0")
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defer c.Close()
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// Create replica on broker.
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b := c.Handler.Broker
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ok(b.CreateReplica("node0"))
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c.Handler.Broker.CreateReplica("node0")
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// Open client to broker.
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u, _ := url.Parse(c.Handler.HTTPServer.URL)
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@ -22,7 +31,7 @@ func TestClient_Open(t *testing.T) {
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t.Fatalf("unexpected error: %s", err)
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}
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// Receive a set of messages from the stream.
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// Receive a message from the stream.
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if m := <-c.C; m.Type != broker.CreateReplicaMessageType {
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t.Fatalf("unexpected message type: %x", m.Type)
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}
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@ -33,6 +42,49 @@ func TestClient_Open(t *testing.T) {
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}
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}
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// Ensure that opening an already open client returns an error.
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func TestClient_Open_ErrClientOpen(t *testing.T) {
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c := NewClient("node0")
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defer c.Close()
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// Open client to broker.
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u, _ := url.Parse(c.Handler.HTTPServer.URL)
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c.Open([]*url.URL{u})
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if err := c.Open([]*url.URL{u}); err != broker.ErrClientOpen {
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t.Fatalf("unexpected error: %s", err)
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}
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}
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// Ensure that opening a client without a broker URL returns an error.
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func TestClient_Open_ErrBrokerURLRequired(t *testing.T) {
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c := NewClient("node0")
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defer c.Close()
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if err := c.Open([]*url.URL{}); err != broker.ErrBrokerURLRequired {
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t.Fatalf("unexpected error: %s", err)
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}
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}
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// Ensure that a client can close while a message is pending.
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func TestClient_Close(t *testing.T) {
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c := NewClient("node0")
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defer c.Close()
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// Create replica on broker.
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c.Handler.Broker.CreateReplica("node0")
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// Open client to broker.
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u, _ := url.Parse(c.Handler.HTTPServer.URL)
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if err := c.Open([]*url.URL{u}); err != nil {
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t.Fatalf("unexpected error: %s", err)
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}
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time.Sleep(10 * time.Millisecond)
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// Close connection to the broker.
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if err := c.Client.Close(); err != nil {
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t.Fatalf("unexpected error: %s", err)
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}
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}
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// Client represents a test wrapper for the broker client.
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type Client struct {
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*broker.Client
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