// Reads from a queue and writes to writer until the queue channel
// is closed. Signals to a WaitGroup when done.
func write(queue chan []byte, writer *syslog.Writer, wg *sync.WaitGroup) {
defer wg.Done()
fmt.Println("writer started")
var totalWrites int64 = 0
var cumuWriteDuration int64 = 0
for line := range queue {
start := time.Now()
writer.Write(line)
//var _ = line
totalWrites++
cumuWriteDuration += time.Now().Sub(start).Nanoseconds() / 1000
}
fmt.Println("writer shutting down")
avgWriteDuration := float64(cumuWriteDuration) / float64(totalWrites)
fmt.Println("total lines written: ", totalWrites)
fmt.Printf("avg write duration (us): %.3v\n", avgWriteDuration)
}
func (this *Server) StartDrainer(address string, filter EntryFilter) *Drainer {
c := make(chan Entry)
listener := &Listener{
Channel: c,
Filter: filter,
LastEntry: time.Now(),
}
this.AddListener <- listener
drainer := &Drainer{
Address: address,
Filter: filter,
server: this,
listener: listener,
terminate: make(chan bool, 1),
}
go func() {
var w *syslog.Writer
var err error
for entry := range Throttle(c, 100) {
for {
// If we terminated give up
select {
case <-drainer.terminate:
return
default:
}
// Connect
if w == nil {
log.Printf("connecting to syslog://%v\n", address)
w, err = syslog.Dial("tcp", address, syslog.LOG_INFO, "")
if err != nil {
w = nil
time.Sleep(time.Second * 5)
continue
}
}
// Send the message
_, err = w.Write(entry.Line())
if err != nil {
w.Close()
w = nil
time.Sleep(time.Second * 5)
continue
}
// Successfully sent the message so break
break
}
}
}()
return drainer
}
// New syslog TCP output.
//
// If the network is empty, the local syslog daemon will be used.
func NewSyslogOutput(network, raddr string, priority syslog.Priority, tag string) (Output, error) {
desc := "syslog"
if network != "" {
desc = fmt.Sprintf("syslog at %s://%s", network, raddr)
}
failing := false
var w *syslog.Writer
dial := func() error {
var err error
w, err = syslog.Dial(network, raddr, priority, tag)
if err != nil {
if !failing {
failing = true
fmt.Fprintf(os.Stderr, "Failed to connect to %s: %s\n", desc, err)
}
w = nil
return err
} else if failing {
fmt.Fprintf(os.Stderr, "Connected to %s\n", desc)
failing = false
}
return nil
}
return newDrainingOutput(10240, func(lines [][]byte) error {
// Connect if a connection does not already exist.
if w == nil {
if err := dial(); err != nil {
return err
}
}
// Send data.
first := true
for _, l := range lines {
if len(l) == 0 {
continue
}
n, err := w.Write(l)
// If the first send fails without sending any data, let's attempt
// to reconnect.
if first {
first = false
if n == 0 && err != nil {
fmt.Fprintf(os.Stderr, "Failed to send data to %s: %s - reconnecting...\n", desc, err)
if err = dial(); err != nil {
return err
}
}
}
// Update the payload and handle any errors.
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to send data to %s: %s\n", desc, err)
failing = true
w.Close()
w = nil
return err
}
}
return nil
}, func() {
if w != nil {
w.Close()
}
})
}