middleware.go

package main

import "time"

var metrics chan string

const (
	THRESHOLD   int = 100
	BUFFER_SIZE int = 1000
)

func init() {
	metrics = make(chan string, BUFFER_SIZE)
}

func processMetrics() {
	var buf []string
	t := time.NewTicker(1 * time.Second)
	for {
		select {
		case s := <-metrics:
			buf = append(buf, s)
			if len(buf) >= THRESHOLD {
				// flush the buffer
				buf = nil
			}
		case <-t.C:
			if len(buf) > 0 {
				// flush the buffer
				buf = nil
			}
		}
	}
}

func main() {
	go processMetrics()
	for {
		// metric collector will be blocking when channel is full
		metrics <- "some metrics"
	}
	
	for {
		// metric collector will be blocking when channel is full
		select {
			case metrics <- "some metrics":
			default:
			fmt.Println("metrics are discarding now, but no influence to service")
		}
	}
}