agent/tcs/handler/handler.go
func ackPublishMetricHandler(timer *time.Timer) func(*ecstcs.AckPublishMetric) {
	return func(*ecstcs.AckPublishMetric) {
		seelog.Debug("Received AckPublishMetric from tcs")
		timer.Reset(retry.AddJitter(defaultHeartbeatTimeout, defaultHeartbeatJitter))
	}
}
func ackPublishMetricHandler(timer *time.Timer) func(*ecstcs.AckPublishMetric) {
	return func(*ecstcs.AckPublishMetric) {
		seelog.Debug("Received AckPublishMetric from tcs")
		timer.Reset(retry.AddJitter(defaultHeartbeatTimeout, defaultHeartbeatJitter))
	}
}
// ackPublishMetricHandler consumes the ack message from the backend. THe backend sends
// the ack each time it processes a metric message.