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sse.go
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sse.go
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package zhttp
import (
"bytes"
"context"
"net/http"
"strconv"
"strings"
"time"
"github.com/sohaha/zlsgo/zerror"
"github.com/sohaha/zlsgo/zstring"
)
type (
SSEEngine struct {
ctx context.Context
eventCh chan *SSEEvent
errCh chan error
ctxCancel context.CancelFunc
verifyHeader func(http.Header) bool
method string
retryNum int
readyState int
}
SSEEvent struct {
ID string
Event string
Undefined []byte
Data []byte
}
)
var (
delim = []byte{':'} // []byte{':', ' '}
ping = []byte("ping")
dataEnd = byte('\n')
)
func (sse *SSEEngine) Event() <-chan *SSEEvent {
return sse.eventCh
}
func (sse *SSEEngine) Close() {
sse.ctxCancel()
}
func (sse *SSEEngine) Done() <-chan struct{} {
return sse.ctx.Done()
}
func (sse *SSEEngine) Error() <-chan error {
return sse.errCh
}
func (sse *SSEEngine) ResetMethod(method string) {
sse.method = method
}
func (sse *SSEEngine) ResetRetryNum(n int) {
sse.retryNum = n
}
func (sse *SSEEngine) VerifyHeader(fn func(http.Header) bool) {
sse.verifyHeader = fn
}
func (sse *SSEEngine) OnMessage(fn func(*SSEEvent, error)) {
for {
select {
case <-sse.Done():
return
case err := <-sse.Error():
fn(nil, err)
case v := <-sse.Event():
fn(v, nil)
}
}
}
func SSE(url string, v ...interface{}) *SSEEngine {
return std.SSE(url, v...)
}
func (e *Engine) sseReq(method, url string, v ...interface{}) (*Res, error) {
r, err := e.Do(method, url, v...)
if err != nil {
return nil, err
}
statusCode := r.resp.StatusCode
if statusCode == http.StatusNoContent {
return nil, nil
}
if statusCode != http.StatusOK {
return nil, zerror.With(zerror.New(zerror.ErrCode(statusCode), r.String()), "status code is "+strconv.Itoa(statusCode))
}
return r, nil
}
func (e *Engine) SSE(url string, v ...interface{}) (sse *SSEEngine) {
var (
retry = 3000
currEvent = &SSEEvent{}
)
ctx, cancel := context.WithCancel(context.TODO())
sse = &SSEEngine{
readyState: 0,
ctx: ctx,
method: "POST",
retryNum: -1,
ctxCancel: cancel,
eventCh: make(chan *SSEEvent),
errCh: make(chan error),
verifyHeader: func(h http.Header) bool {
return strings.Contains(h.Get("Content-Type"), "text/event-stream")
},
}
lastID := ""
go func() {
for {
if sse.ctx.Err() != nil {
break
}
data := v
if lastID != "" {
data = append(data, Header{"Last-Event-ID": lastID})
}
data = append(data, Header{"Accept": "text/event-stream"})
data = append(data, Header{"Connection": "keep-alive"})
data = append(data, sse.ctx)
r, err := e.sseReq(sse.method, url, data...)
if err == nil {
if r != nil {
if sse.verifyHeader != nil && !sse.verifyHeader(r.Response().Header) {
sse.eventCh <- &SSEEvent{
Undefined: r.Bytes(),
}
r = nil
}
}
if r == nil {
sse.readyState = 2
cancel()
return
}
sse.readyState = 1
isPing := false
_ = r.Stream(func(line []byte, eof bool) error {
i := len(line)
if i == 1 && line[0] == dataEnd {
if !isPing {
sse.eventCh <- currEvent
currEvent = &SSEEvent{}
isPing = false
} else {
currEvent = &SSEEvent{}
}
return nil
}
if i < 2 {
return nil
}
spl := bytes.SplitN(line, delim, 2)
if len(spl) < 2 {
currEvent.Undefined = line
return nil
}
if len(spl[0]) == 0 {
isPing = bytes.Equal(ping, bytes.TrimSpace(spl[1]))
if !isPing {
currEvent.Undefined = spl[1]
}
return nil
}
val := bytes.TrimSuffix(spl[1], []byte{'\n'})
val = bytes.TrimPrefix(val, []byte{' '})
switch zstring.Bytes2String(spl[0]) {
case "id":
lastID = zstring.Bytes2String(val)
currEvent.ID = lastID
case "event":
currEvent.Event = zstring.Bytes2String(val)
case "data":
if len(currEvent.Data) > 0 {
sse.eventCh <- currEvent
currEvent = &SSEEvent{}
isPing = false
}
currEvent.Data = append(currEvent.Data, val...)
case "retry":
if t, err := strconv.Atoi(zstring.Bytes2String(val)); err == nil {
retry = t
}
}
if eof && !isPing {
sse.eventCh <- currEvent
currEvent = &SSEEvent{}
}
return nil
})
if sse.retryNum >= 0 {
if sse.retryNum == 0 {
cancel()
return
}
sse.retryNum--
}
} else {
sse.errCh <- err
}
sse.readyState = 0
time.Sleep(time.Millisecond * time.Duration(retry))
}
}()
return
}