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alert.go
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alert.go
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package ucp
import (
"bufio"
"sync"
"time"
)
type alert struct {
AdC []byte
PID []byte
}
func (a alert) Code() []byte {
return []byte(opAlert)
}
func (a alert) Type() []byte {
return []byte(operationType)
}
// ping returns a []byte to send as a keep-alive
func ping(transRefNum []byte, user string) []byte {
a := alert{
AdC: []byte(user),
PID: []byte(pcAppOverTcpIp),
}
buf := preparePacket(transRefNum, a)
return buf
}
// sendAlert writes an alert packet to the socket every alertInterval.
func sendAlert(transRefNum []byte, user string, writer *bufio.Writer, wg *sync.WaitGroup,
closeChan chan struct{}, alertInterval time.Duration, mu *sync.Mutex, logger Logger) {
wg.Add(1)
ticker := time.NewTicker(alertInterval)
go func() {
defer wg.Done()
for {
select {
case <-closeChan:
ticker.Stop()
logger.Printf("stopped ticker\n")
logger.Printf("sendAlert terminated\n")
return
case <-ticker.C:
mu.Lock()
if _, err := writer.Write(ping(transRefNum, user)); err != nil {
logger.Printf("error writing ping: %v\n", err)
}
if err := writer.Flush(); err != nil {
logger.Printf("error flushing ping: %v\n", err)
}
mu.Unlock()
}
}
}()
}