// _[Rate limiting](http://en.wikipedia.org/wiki/Rate_limiting)_ // is an important mechanism for controlling resource // utilization and maintaining quality of service. Go // elegantly supports rate limiting with goroutines, // channels, and [tickers](tickers). // 流量控制是控制资源利用率和保持服务质量的一个重要机制。 // go语言用goroutin，channel和 tickers优美的支持了流量控制。
package main
import"time" import"fmt"
func main() {
// First we'll look at basic rate limiting. Suppose // we want to limit our handling of incoming requests. // We'll serve these requests off a channel of the // same name. // 首先我们看看基本的流量控制。假设我们需要限制在处理的请求。 // 我们会为这些请求的采用相同channel。 requests := make(chanint, 5) for i := 1; i <= 5; i++ { requests <- i } close(requests)
// This `limiter` channel will receive a value // every 200 milliseconds. This is the regulator in // our rate limiting scheme. // 这个限流的channel将会每200毫秒收到一个值。 // 这是一个调节我们限制速率的一个方案。 limiter := time.Tick(time.Millisecond * 200)
// By blocking on a receive from the `limiter` channel // before serving each request, we limit ourselves to // 1 request every 200 milliseconds. // 在服务每个请求之前,阻塞`limiter`,以此, // 我们限制每200ms1个请求. for req := range requests { <-limiter fmt.Println("request", req, time.Now()) }
// We may want to allow short bursts of requests in // our rate limiting scheme while preserving the // overall rate limit. We can accomplish this by // buffering our limiter channel. This `burstyLimiter` // channel will allow bursts of up to 3 events. // 我们也许想有一个短小并发在限流里面，但是整体上是限流的。 // 这可以通过有缓冲限制的channel来实现。 // burstyLimiter channel 将只允许最多3个并发事件。 burstyLimiter := make(chan time.Time, 3)
// Fill up the channel to represent allowed bursting. // 填充表示允许并发的 channel。 for i := 0; i < 3; i++ { burstyLimiter <- time.Now() }
// Every 200 milliseconds we'll try to add a new // value to `burstyLimiter`, up to its limit of 3. // 每200毫秒我们试着添加新的值到burstyLimiter，最多3个。 gofunc() { for t := range time.Tick(time.Millisecond * 200) { burstyLimiter <- t } }()
// Now simulate 5 more incoming requests. The first // 3 of these will benefit from the burst capability // of `burstyLimiter`. // 现在模拟5个请求。前三个将受益于有并发能力的burstyLimiter。 burstyRequests := make(chanint, 5) for i := 1; i <= 5; i++ { burstyRequests <- i } close(burstyRequests) for req := range burstyRequests { <-burstyLimiter fmt.Println("request", req, time.Now()) } }
