80 lines
1.3 KiB
Go
80 lines
1.3 KiB
Go
package gateway
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import (
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"time"
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"github.com/pkg/errors"
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)
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var ErrDead = errors.New("no heartbeat replied")
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type Pacemaker struct {
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// Heartrate is the received duration between heartbeats.
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Heartrate time.Duration
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// LastBeat logs the received heartbeats, with the newest one
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// first.
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LastBeat [2]time.Time
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// Any callback that returns an error will stop the pacer.
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Pace func() error
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// Event
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OnDead func() error
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stop chan<- struct{}
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}
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func (p *Pacemaker) Echo() {
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// Swap our received heartbeats
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p.LastBeat[0], p.LastBeat[1] = time.Now(), p.LastBeat[0]
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}
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// Dead, if true, will have Pace return an ErrDead.
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func (p *Pacemaker) Dead() bool {
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if p.LastBeat[0].IsZero() || p.LastBeat[1].IsZero() {
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return false
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}
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return p.LastBeat[0].Sub(p.LastBeat[1]) > p.Heartrate*2
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}
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func (p *Pacemaker) Stop() {
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close(p.stop)
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}
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// Start beats until it's dead.
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func (p *Pacemaker) Start() error {
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tick := time.NewTicker(p.Heartrate)
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defer tick.Stop()
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stop := make(chan struct{})
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p.stop = stop
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for {
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if err := p.Pace(); err != nil {
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return err
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}
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if p.Dead() {
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if err := p.OnDead(); err != nil {
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return err
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}
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}
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select {
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case <-stop:
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return nil
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case <-tick.C:
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continue
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}
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}
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}
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func (p *Pacemaker) StartAsync() (death <-chan error) {
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var ch = make(chan error)
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go func() {
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ch <- p.Start()
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}()
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return ch
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}
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