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dial.go
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dial.go
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package websocket
import (
"context"
"fmt"
"net/http"
"time"
"github.com/gorilla/websocket"
"github.com/shenghui0779/yiigo/hash"
"golang.org/x/sync/singleflight"
)
var dialer = websocket.DefaultDialer
// SetDialer 设置 websocket dialer
func SetDialer(d *websocket.Dialer) {
dialer = d
}
// DialConn websocket拨号连接,支持(读/写)失败重连
type DialConn struct {
key string
addr string
header http.Header
conn *websocket.Conn
mutex singleflight.Group
}
func (c *DialConn) reconnect() error {
// 并发安全,多次请求只会重连一次
ch := c.mutex.DoChan(c.key, func() (interface{}, error) {
// 创建新连接
conn, _, err := dialer.Dial(c.addr, c.header)
if err != nil {
return false, err
}
// 关闭原连接
c.conn.Close()
// 设置新连接
c.conn = conn
return true, nil
})
// 设置超时,以防阻塞
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
select {
case <-ctx.Done(): // 超时
c.mutex.Forget(c.key)
return ctx.Err()
case r := <-ch:
if r.Err != nil {
c.mutex.Forget(c.key)
return r.Err
}
if !r.Shared {
// 2秒后清除缓存
go func() {
time.Sleep(2 * time.Second)
c.mutex.Forget(c.key)
}()
}
}
return nil
}
// Read 读消息,若失败会尝试重连 (reconnectTimeout<=0 表示重连不超时)
func (c *DialConn) Read(reconnectTimeout time.Duration, handler func(msg *Message)) error {
for {
t, b, err := c.conn.ReadMessage()
if err == nil {
handler(NewMessage(t, b))
continue
}
var cancel context.CancelFunc
ctx := context.Background()
if reconnectTimeout > 0 {
ctx, cancel = context.WithTimeout(ctx, reconnectTimeout)
}
// 尝试重连
for {
select {
case <-ctx.Done():
if cancel != nil {
cancel()
}
return fmt.Errorf("websocket reconnect timeout: %w", ctx.Err())
default:
}
// 500毫秒后尝试重连
time.Sleep(500 * time.Millisecond)
if err = c.reconnect(); err == nil {
if cancel != nil {
cancel()
}
break
}
}
}
}
// Write 写消息,若失败会尝试重连 (reconnectTimeout<=0 表示重连不超时)
func (c *DialConn) Write(reconnectTimeout time.Duration, msg *Message) error {
for {
err := c.conn.WriteMessage(msg.T(), msg.V())
if err == nil {
return nil
}
var cancel context.CancelFunc
ctx := context.Background()
if reconnectTimeout > 0 {
ctx, cancel = context.WithTimeout(ctx, reconnectTimeout)
}
// 尝试重连
for {
select {
case <-ctx.Done():
if cancel != nil {
cancel()
}
return fmt.Errorf("websocket reconnect timeout: %w", ctx.Err())
default:
}
// 500毫秒后尝试重连
time.Sleep(500 * time.Millisecond)
if err = c.reconnect(); err == nil {
if cancel != nil {
cancel()
}
break
}
}
}
}
// Close 关闭连接
func (c *DialConn) Close() error {
return c.conn.Close()
}
// Dial 创建一个websocket拨号连接
func Dial(ctx context.Context, addr string, header http.Header) (*DialConn, error) {
conn, _, err := dialer.DialContext(ctx, addr, header)
if err != nil {
return nil, err
}
return &DialConn{
key: hash.MD5(addr),
addr: addr,
header: header,
conn: conn,
}, nil
}