forgejo/modules/eventsource/event.go

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// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package eventsource
import (
"bytes"
"fmt"
"io"
"strings"
"time"
jsoniter "github.com/json-iterator/go"
)
func wrapNewlines(w io.Writer, prefix []byte, value []byte) (sum int64, err error) {
if len(value) == 0 {
return
}
n := 0
last := 0
for j := bytes.IndexByte(value, '\n'); j > -1; j = bytes.IndexByte(value[last:], '\n') {
n, err = w.Write(prefix)
sum += int64(n)
if err != nil {
return
}
n, err = w.Write(value[last : last+j+1])
sum += int64(n)
if err != nil {
return
}
last += j + 1
}
n, err = w.Write(prefix)
sum += int64(n)
if err != nil {
return
}
n, err = w.Write(value[last:])
sum += int64(n)
if err != nil {
return
}
n, err = w.Write([]byte("\n"))
sum += int64(n)
return
}
// Event is an eventsource event, not all fields need to be set
type Event struct {
// Name represents the value of the event: tag in the stream
Name string
// Data is either JSONified []byte or interface{} that can be JSONd
Data interface{}
// ID represents the ID of an event
ID string
// Retry tells the receiver only to attempt to reconnect to the source after this time
Retry time.Duration
}
// WriteTo writes data to w until there's no more data to write or when an error occurs.
// The return value n is the number of bytes written. Any error encountered during the write is also returned.
func (e *Event) WriteTo(w io.Writer) (int64, error) {
sum := int64(0)
nint := 0
n, err := wrapNewlines(w, []byte("event: "), []byte(e.Name))
sum += n
if err != nil {
return sum, err
}
if e.Data != nil {
var data []byte
switch v := e.Data.(type) {
case []byte:
data = v
case string:
data = []byte(v)
default:
var err error
json := jsoniter.ConfigCompatibleWithStandardLibrary
data, err = json.Marshal(e.Data)
if err != nil {
return sum, err
}
}
n, err := wrapNewlines(w, []byte("data: "), data)
sum += n
if err != nil {
return sum, err
}
}
n, err = wrapNewlines(w, []byte("id: "), []byte(e.ID))
sum += n
if err != nil {
return sum, err
}
if e.Retry != 0 {
nint, err = fmt.Fprintf(w, "retry: %d\n", int64(e.Retry/time.Millisecond))
sum += int64(nint)
if err != nil {
return sum, err
}
}
nint, err = w.Write([]byte("\n"))
sum += int64(nint)
return sum, err
}
func (e *Event) String() string {
buf := new(strings.Builder)
_, _ = e.WriteTo(buf)
return buf.String()
}