add rate limiter

Author: github-vincent-miszczak

README.md

@@ -18,10 +18,13 @@ Usage of ./whisper-to-graphite:
     	Hostname/IP of the graphite server (default "127.0.0.1")
   -port int
     	graphite Port (default 2003)
+  -pps int
+    	Number of maximum points per second to send (0 means rate limiter is disabled)
   -protocol string
     	Protocol to use to transfer graphite data (tcp/udp/nop) (default "tcp")
   -workers int
-        Workers to run in parallel (default 5)
+    	Workers to run in parallel (default 5)
+
 ```
 
 Assuming you don't want to use this as testcase for your IO subsystem,

dump.go

@@ -3,17 +3,65 @@ package main
 import (
 	"errors"
 	"flag"
-	"github.com/bzed/go-whisper"
-	"github.com/marpaia/graphite-golang"
 	"log"
 	"math"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"sync"
+	"time"
+
+	"github.com/bzed/go-whisper"
+	"github.com/marpaia/graphite-golang"
 )
 
+type rateLimiter struct {
+	pointsPerSecond int64
+	currentPoints   int64
+	full            chan bool
+	lock            *sync.Mutex
+	enabled         bool
+}
+
+func newRateLimiter(pointsPerSecond int64) *rateLimiter {
+	rl := new(rateLimiter)
+	rl.pointsPerSecond = pointsPerSecond
+	rl.currentPoints = 0
+	rl.full = make(chan bool)
+	rl.lock = new(sync.Mutex)
+	if pointsPerSecond == 0 {
+		rl.enabled = false
+	} else {
+		rl.enabled = true
+		go func() {
+			for {
+				time.Sleep(1 * time.Second)
+				select {
+				case <-rl.full:
+				default:
+				}
+			}
+		}()
+		return rl
+	}
+	return rl
+}
+
+func (rl *rateLimiter) limit(n int64) {
+	if !rl.enabled {
+		return
+	}
+	rl.lock.Lock()
+	defer rl.lock.Unlock()
+
+	rl.currentPoints += n
+	if rl.currentPoints >= rl.pointsPerSecond {
+		rl.full <- true
+		rl.currentPoints = 0
+	}
+}
+
 func convertFilename(filename string, baseDirectory string) (string, error) {
 	absFilename, err := filepath.Abs(filename)
 	if err != nil {
@@ -48,6 +96,7 @@ func sendWhisperData(
 	graphiteConn *graphite.Graphite,
 	fromTs int,
 	toTs int,
+	rateLimiter *rateLimiter,
 ) error {
 	metricName, err := convertFilename(filename, baseDirectory)
 	if err != nil {
@@ -75,6 +124,7 @@ func sendWhisperData(
 		metrics = append(metrics, graphite.NewMetric(metricName, v, int64(interval)))
 
 	}
+	rateLimiter.limit(int64(len(metrics)))
 	err = graphiteConn.SendMetrics(metrics)
 	if err != nil {
 		return err
@@ -107,8 +157,8 @@ func worker(ch chan string,
 	graphitePort int,
 	graphiteProtocol string,
 	fromTs int,
-	toTs int) {
-
+	toTs int,
+	rateLimiter *rateLimiter) {
 	defer wg.Done()
 
 	graphiteConn, err := graphite.GraphiteFactory(graphiteProtocol, graphiteHost, graphitePort, "")
@@ -121,7 +171,7 @@ func worker(ch chan string,
 		case path := <-ch:
 			{
 
-				err := sendWhisperData(path, baseDirectory, graphiteConn, fromTs, toTs)
+				err := sendWhisperData(path, baseDirectory, graphiteConn, fromTs, toTs, rateLimiter)
 				if err != nil {
 					log.Println("Failed: " + path)
 					log.Println(err)
@@ -170,6 +220,10 @@ func main() {
 		"to",
 		2147483647,
 		"Ending timestamp to dump data up to")
+	pointsPerSecond := flag.Int64(
+		"pps",
+		0,
+		"Number of maximum points per second to send (0 means rate limiter is disabled)")
 	flag.Parse()
 
 	if !(*graphiteProtocol == "tcp" ||
@@ -181,9 +235,10 @@ func main() {
 	quit := make(chan int)
 	var wg sync.WaitGroup
 
+	rl := newRateLimiter(*pointsPerSecond)
 	wg.Add(*workers)
 	for i := 0; i < *workers; i++ {
-		go worker(ch, quit, &wg, *baseDirectory, *graphiteHost, *graphitePort, *graphiteProtocol, *fromTs, *toTs)
+		go worker(ch, quit, &wg, *baseDirectory, *graphiteHost, *graphitePort, *graphiteProtocol, *fromTs, *toTs, rl)
 	}
 	go findWhisperFiles(ch, quit, *directory)
 	wg.Wait()