Currently I am working on an application that can take anywhere from a few seconds to 1 hour + to process. Because of this using a channel to block requests while others are processing seems like a good fit. The following is an example of what Im trying to accomplish, however I am having an issue as it seems like my program is stalling when trying to add data into said channel (see below).
package main
import (
"net/http"
"github.com/gorilla/mux"
)
type Request struct {
Id string
}
func ConstructRequest(id string) Request {
return Request{Id: id}
}
var requestChannel chan Request // <- Create var for channel
func init() {
r := mux.NewRouter()
r.HandleFunc("/request/{id:[0-9]+}", ProcessRequest).Methods("GET")
http.Handle("/", r)
}
func main() {
// start server
http.ListenAndServe(":4000", nil)
requestChannel = make(chan Request) // <- Make channel and assign to var
go func() {
for {
request, ok := <-requestChannel
if !ok{
return
}
fmt.Println(request.Id)
}
}()
}
func ProcessRequest(w http.ResponseWriter, r *http.Request) {
params := mux.Vars(r)
newRequest := api.ConstructRequest(params["id"])
requestChannel <- newRequest // <- it is stopping here, not adding the value to the channel
w.Write([]byte("Received request"))
}
Your channel is not initialised and, per specification, send on a nil channel blocks forever. This is because http.ListenAndServe is a blocking operation, so neither requestChannel = make(chan Request) nor your go func() is being called.
Moving http.ListenAndServe to the end of the main block should fix the problem.