stopwatch

README

Stopwatch

A small library to measure latency of things.

It can measure:

1. Arbitrary closure's latency.

2. Request latency via middleware pattern.

Five Minutes Tutorial

1. Closure

package main

import (
    "fmt"
    "github.com/didip/stopwatch"
)

func main() {
    a := 1
    f := func() {
        for i := 1; i <= 10; i++ {
            a = a + 1
        }
    }

    latency := stopwatch.Measure(f)

    fmt.Printf("Latency in nanoseconds: %v, Result: %v\n", latency, a)
}

2. Middleware

package main

import (
    "fmt"
    "github.com/didip/stopwatch"
    "net/http"
)

func HelloHandler(w http.ResponseWriter, req *http.Request) {
    w.Write([]byte("Hello, World!"))
}

func main() {
    // 1. Create a channel to receive latency result
    helloHandlerLatencyChan := make(chan int64)

    // 2. Pull latency result asynchronously.
    go func() {
        for {
            select {
            case latency := <-helloHandlerLatencyChan:
                fmt.Printf("Latency of HelloHandler in nanoseconds: %v\n", latency)
            }
        }
    }()

    fmt.Println("Starting HTTP server on :12345")
    http.Handle("/", stopwatch.LatencyFuncHandler(helloHandlerLatencyChan, []string{"GET"}, HelloHandler))
    http.ListenAndServe(":12345", nil)
}

My other Go libraries

• Tollbooth: Simple middleware to rate-limit HTTP requests.

• Gomet: Simple HTTP client & server long poll library for Go. Useful for receiving live updates without needing Websocket.

Documentation

Index

• func LatencyFuncHandler(resultChan chan int64, methods []string, ...) http.Handler
• func LatencyHandler(resultChan chan int64, methods []string, next http.Handler) http.Handler
• func Measure(f func()) int64

Functions

func LatencyFuncHandler

func LatencyFuncHandler(resultChan chan int64, methods []string, nextFunc func(http.ResponseWriter, *http.Request)) http.Handler

LatencyFuncHandler is a middleware that measures latency given request handler function.

func LatencyHandler

func LatencyHandler(resultChan chan int64, methods []string, next http.Handler) http.Handler

LatencyHandler is a middleware that measures latency given http.Handler struct.

func Measure

func Measure(f func()) int64

Measure latency in nanoseconds