rate_limiter.go

package main

import (
    "fmt"
    "math/rand"
    "sync"
    "time"
)

func main() {
    count := 50
    ch := make(chan int, count)
    RPCCall := MakeRPCCall()
    wg := sync.WaitGroup{}
    for i := 0; i < count; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            ch <- RPCCall()
        }()
    }

    wg.Wait()
    close(ch)
    for value := range ch {
        fmt.Println(value)
    }
}

const rateLimit = 10

func MakeRPCCall() func() int {
    jobs := make(chan struct{}, rateLimit)
    go func() {
        for {
            time.Sleep(time.Second)
            chanLen := len(jobs)
            if chanLen > rateLimit {
                chanLen = rateLimit
            }
            for i := 0; i < chanLen; i++ {
                <-jobs
            }
        }
    }()
    return func() int {
        jobs <- struct{}{}
        return rand.Int()
    }
}