/
websocket.go
281 lines (234 loc) · 5.03 KB
/
websocket.go
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package transport
import (
"encoding/json"
"fmt"
"net/http"
"sync"
"sync/atomic"
"time"
"github.com/boolw/go-web3/jsonrpc/codec"
"github.com/gorilla/websocket"
)
func newWebsocket(url string) (Transport, error) {
wsConn, _, err := websocket.DefaultDialer.Dial(url, http.Header{})
if err != nil {
return nil, err
}
codec := &websocketCodec{
conn: wsConn,
}
return newStream(codec)
}
// ErrTimeout happens when the websocket requests times out
var ErrTimeout = fmt.Errorf("timeout")
type ackMessage struct {
buf []byte
err error
}
type callback func(b []byte, err error)
type stream struct {
seq uint64
codec Codec
// call handlers
handlerLock sync.Mutex
handler map[uint64]callback
// subscriptions
subsLock sync.Mutex
subs map[string]func(b []byte)
closeCh chan struct{}
timer *time.Timer
}
func newStream(codec Codec) (*stream, error) {
w := &stream{
codec: codec,
closeCh: make(chan struct{}),
handler: map[uint64]callback{},
subs: map[string]func(b []byte){},
}
go w.listen()
return w, nil
}
// Close implements the the transport interface
func (s *stream) Close() error {
close(s.closeCh)
return s.codec.Close()
}
func (s *stream) incSeq() uint64 {
return atomic.AddUint64(&s.seq, 1)
}
func (s *stream) isClosed() bool {
select {
case <-s.closeCh:
return true
default:
return false
}
}
func (s *stream) listen() {
buf := []byte{}
for {
var err error
buf, err = s.codec.Read(buf[:0])
if err != nil {
if !s.isClosed() {
// log error
}
return
}
var resp codec.Response
if err = json.Unmarshal(buf, &resp); err != nil {
return
}
if resp.ID != 0 {
go s.handleMsg(resp)
} else {
// handle subscription
var respSub codec.Request
if err = json.Unmarshal(buf, &respSub); err != nil {
return
}
if respSub.Method == "eth_subscription" {
go s.handleSubscription(respSub)
}
}
}
}
func (s *stream) handleSubscription(response codec.Request) {
var sub codec.Subscription
if err := json.Unmarshal(response.Params, &sub); err != nil {
panic(err)
}
s.subsLock.Lock()
callback, ok := s.subs[sub.ID]
s.subsLock.Unlock()
if !ok {
return
}
// call the callback function
callback(sub.Result)
}
func (s *stream) handleMsg(response codec.Response) {
s.handlerLock.Lock()
callback, ok := s.handler[response.ID]
if !ok {
s.handlerLock.Unlock()
return
}
// delete handler
delete(s.handler, response.ID)
s.handlerLock.Unlock()
if response.Error != nil {
callback(nil, response.Error)
} else {
callback(response.Result, nil)
}
}
func (s *stream) setHandler(id uint64, ack chan *ackMessage) {
callback := func(b []byte, err error) {
select {
case ack <- &ackMessage{b, err}:
default:
}
}
s.handlerLock.Lock()
s.handler[id] = callback
s.handlerLock.Unlock()
s.timer = time.AfterFunc(5*time.Second, func() {
s.handlerLock.Lock()
delete(s.handler, id)
s.handlerLock.Unlock()
select {
case ack <- &ackMessage{nil, ErrTimeout}:
default:
}
})
}
// Call implements the transport interface
func (s *stream) Call(method string, out interface{}, params ...interface{}) error {
seq := s.incSeq()
request := codec.Request{
ID: seq,
Method: method,
Jsonrpc: "2.0",
}
if len(params) > 0 {
data, err := json.Marshal(params)
if err != nil {
return err
}
request.Params = data
}
ack := make(chan *ackMessage)
s.setHandler(seq, ack)
raw, err := json.Marshal(request)
if err != nil {
return err
}
if err := s.codec.Write(raw); err != nil {
return err
}
resp := <-ack
if resp.err != nil {
return resp.err
}
if err := json.Unmarshal(resp.buf, out); err != nil {
return err
}
return nil
}
func (s *stream) unsubscribe(id string) error {
s.subsLock.Lock()
defer s.subsLock.Unlock()
if _, ok := s.subs[id]; !ok {
return fmt.Errorf("subscription %s not found", id)
}
delete(s.subs, id)
var result bool
if err := s.Call("eth_unsubscribe", &result, id); err != nil {
return err
}
if !result {
return fmt.Errorf("failed to unsubscribe")
}
return nil
}
func (s *stream) setSubscription(id string, callback func(b []byte)) {
s.subsLock.Lock()
defer s.subsLock.Unlock()
s.subs[id] = callback
}
// Subscribe implements the PubSubTransport interface
func (s *stream) Subscribe(method string, callback func(b []byte)) (func() error, error) {
var out string
if err := s.Call("eth_subscribe", &out, method); err != nil {
return nil, err
}
s.setSubscription(out, callback)
cancel := func() error {
return s.unsubscribe(out)
}
return cancel, nil
}
type websocketCodec struct {
conn *websocket.Conn
}
func (w *websocketCodec) Close() error {
return w.conn.Close()
}
func (w *websocketCodec) Write(b []byte) error {
return w.conn.WriteMessage(websocket.TextMessage, b)
}
func (w *websocketCodec) Read(b []byte) ([]byte, error) {
_, buf, err := w.conn.ReadMessage()
if err != nil {
return nil, err
}
b = append(b, buf...)
return b, nil
}
// Codec is the codec to write and read messages
type Codec interface {
Read([]byte) ([]byte, error)
Write([]byte) error
Close() error
}