func (c *Channel) Watch(accepts ...int32) {
	c.mutex.Lock()
	for _, op := range accepts {
		c.watchOps[op] = struct{}{}
	}
	c.mutex.Unlock()
}
Watch watch a operation.
package comet
import (
	"sync"
	"github.com/tsingson/ex-goim/api/comet/grpc"
	"github.com/tsingson/ex-goim/pkg/bufio"
)
type Channel struct {
	Room     *Room
	CliProto Ring
	signal   chan *grpc.Proto
	Writer   bufio.Writer
	Reader   bufio.Reader
	Next     *Channel
	Prev     *Channel
	Mid      int64  
	Key      string
	IP       string
	watchOps map[int32]struct{}
	mutex    sync.RWMutex
}
func NewChannel(cli, svr int) *Channel {
	c := new(Channel)
	c.CliProto.Init(cli)
	c.signal = make(chan *grpc.Proto, svr)
	c.watchOps = make(map[int32]struct{})
	return c
}