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outlet.go
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outlet.go
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package channel
import (
"sync"
"sync/atomic"
"github.com/elastic/beats/filebeat/util"
)
// Outlet struct is used to be passed to an object which needs an outlet
//
// The difference between signal and done channel is as following:
// - signal channel can be added through SetSignal and is used to
// interrupt events sent through OnEventSignal-
// - done channel is used to close and stop the outlet
//
// If SetSignal is used, it must be ensure that there is only one event producer.
type Outlet struct {
wg *sync.WaitGroup // Use for counting active events
done <-chan struct{}
signal <-chan struct{}
channel chan *util.Data
isOpen int32 // atomic indicator
}
func NewOutlet(
done <-chan struct{},
c chan *util.Data,
wg *sync.WaitGroup,
) *Outlet {
return &Outlet{
done: done,
channel: c,
wg: wg,
isOpen: 1,
}
}
// SetSignal sets the signal channel for OnEventSignal
// If SetSignal is used, it must be ensure that only one producer exists.
func (o *Outlet) SetSignal(signal <-chan struct{}) {
o.signal = signal
}
func (o *Outlet) OnEvent(data *util.Data) bool {
open := atomic.LoadInt32(&o.isOpen) == 1
if !open {
return false
}
if o.wg != nil {
o.wg.Add(1)
}
select {
case <-o.done:
if o.wg != nil {
o.wg.Done()
}
atomic.StoreInt32(&o.isOpen, 0)
return false
case o.channel <- data:
return true
}
}
// OnEventSignal can be stopped by the signal that is set with SetSignal
// This does not close the outlet. Only OnEvent does close the outlet.
// If OnEventSignal is used, it must be ensured that only one producer is used.
func (o *Outlet) OnEventSignal(data *util.Data) bool {
open := atomic.LoadInt32(&o.isOpen) == 1
if !open {
return false
}
if o.wg != nil {
o.wg.Add(1)
}
select {
case <-o.signal:
if o.wg != nil {
o.wg.Done()
}
o.signal = nil
return false
case o.channel <- data:
return true
}
}
func (o *Outlet) Copy() Outleter {
return NewOutlet(o.done, o.channel, o.wg)
}