NOTE: a new and improved implementation is available at https://github.com/go-chi/stampede

Just a little bit of performance enhancing middleware -- HTTP Coala (aka Coalescer).

HTTP Coala is a middleware handler that routes multiple requests for the same URI (and routed methods) to be processed as a single request. I don't recommend it for every web service or handler chain, but for the computationally expensive handlers that always yield the same response, HTTP Coala will give you a speed boost.

It's common among HTTP reverse proxy cache servers such as nginx, Squid or Varnish - they all call it something else but works similarly.

• https://www.varnish-cache.org/docs/3.0/tutorial/handling_misbehaving_servers.html
• http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_lock
• http://wiki.squid-cache.org/Features/CollapsedForwarding

Example with goji

// from _example/main.go ....
func main() {
	r := chi.NewRouter()

	r.Use(middleware.Logger)
	r.Use(httpcoala.Route("HEAD", "GET")) // or, Route("*")
	// r.Use(otherMiddleware)

	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(100 * time.Millisecond) // expensive op
		w.WriteHeader(200)
		w.Write([]byte("hi"))
	})

	http.ListenAndServe(":1111", r)
}

as well, look at httpcoala_test.go

For a naive benchmark on my local Macbook pro, I used wrk with -c 100 and -t 100 on a web service that downloads an image and returns a resized version.

Without httpcoala middleware, Requests/sec:   7081.09
   With httpcoala middleware, Requests/sec:  18373.87

• Allow a request key to be passed that determines when to coalesce requests. It would allow for more control such as grouping by a query param or header.

Brought to you by the Pressly Go team - www.pressly.com / https://github.com/pressly

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