Merge pull request #120 from benburkert/simplify-newserver

redoctober: simplify the NewServer signature

redoctober.go

@@ -17,10 +17,11 @@ import (
 	"net"
 	"net/http"
 	"os"
-	"runtime"
 	"strings"
 	"time"
 
+	"golang.org/x/net/netutil"
+
 	"github.com/cloudflare/redoctober/core"
 	"github.com/coreos/go-systemd/activation"
 )
@@ -56,29 +57,33 @@ type userRequest struct {
 	// called to handle this request)
 }
 
-// queueRequest handles a single request receive on the JSON API for
-// one of the functions named in the functions map above. It reads the
-// request and sends it to the goroutine started in main() below for
-// processing and then waits for the response.
-func queueRequest(process chan<- userRequest, requestType string, w http.ResponseWriter, r *http.Request) {
+// processRequest handles a single request receive on the JSON API for
+// one of the functions named in the functions map above.
+func processRequest(requestType string, w http.ResponseWriter, r *http.Request) {
+	header := w.Header()
+	header.Set("Content-Type", "application/json")
+	header.Set("Strict-Transport-Security", "max-age=86400; includeSubDomains; preload")
+
+	fn, ok := functions[requestType]
+	if !ok {
+		http.Error(w, "Unknown request", http.StatusInternalServerError)
+		return
+	}
+
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
-	response := make(chan []byte)
-	process <- userRequest{rt: requestType, in: body, resp: response}
-
-	if resp, ok := <-response; ok {
-		header := w.Header()
-		header.Set("Content-Type", "application/json")
-		header.Set("Strict-Transport-Security", "max-age=86400; includeSubDomains; preload")
-
-		w.Write(resp)
-	} else {
-		http.Error(w, "Unknown request", http.StatusInternalServerError)
+	resp, err := fn(body)
+	if err != nil {
+		log.Printf("http.main failed: %s: %s", requestType, err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
 	}
+
+	w.Write(resp)
 }
 
 // NewServer starts an HTTPS server the handles the redoctober JSON
@@ -88,7 +93,7 @@ func queueRequest(process chan<- userRequest, requestType string, w http.Respons
 //
 // Returns a valid http.Server handling redoctober JSON requests (and
 // its associated listener) or an error
-func NewServer(process chan<- userRequest, staticPath, addr, caPath string, certPaths, keyPaths []string, useSystemdSocket bool) (*http.Server, net.Listener, error) {
+func NewServer(staticPath, addr, caPath string, certPaths, keyPaths []string, useSystemdSocket bool) (*http.Server, net.Listener, error) {
 	config := &tls.Config{
 		PreferServerCipherSuites: true,
 		SessionTicketsDisabled:   true,
@@ -155,7 +160,7 @@ func NewServer(process chan<- userRequest, staticPath, addr, caPath string, cert
 		requestType := current
 		mux.HandleFunc(requestType, func(w http.ResponseWriter, r *http.Request) {
 			log.Printf("http.server: endpoint=%s remote=%s", requestType, r.RemoteAddr)
-			queueRequest(process, requestType, w, r)
+			processRequest(requestType, w, r)
 		})
 	}
 
@@ -170,6 +175,11 @@ func NewServer(process chan<- userRequest, staticPath, addr, caPath string, cert
 		TLSConfig: config,
 	}
 
+	// The core package is not safe to be shared across goroutines so
+	// this supervisor goroutine reads requests from the process
+	// channel and dispatches them to core for processes.
+	lstnr = netutil.LimitListener(lstnr, 1)
+
 	return &srv, lstnr, nil
 }
 
@@ -243,37 +253,7 @@ func main() {
 		log.Fatalf(err.Error())
 	}
 
-	runtime.GOMAXPROCS(runtime.NumCPU())
-
-	// The core package is not safe to be shared across goroutines so
-	// this supervisor goroutine reads requests from the process
-	// channel and dispatches them to core for processes.
-
-	process := make(chan userRequest)
-	go func() {
-		for {
-			req := <-process
-			if f, ok := functions[req.rt]; ok {
-				r, err := f(req.in)
-				if err == nil {
-					req.resp <- r
-				} else {
-					log.Printf("http.main failed: %s: %s", req.rt, err)
-				}
-			} else {
-				log.Printf("http.main: request=%s function is not supported", req.rt)
-			}
-
-			// Note that if an error occurs no message is sent down
-			// the channel and then channel is closed. The
-			// queueRequest function will see this as indication of an
-			// error.
-
-			close(req.resp)
-		}
-	}()
-
-	s, l, err := NewServer(process, *staticPath, *addr, *caPath, certPaths, keyPaths, *useSystemdSocket)
+	s, l, err := NewServer(*staticPath, *addr, *caPath, certPaths, keyPaths, *useSystemdSocket)
 	if err != nil {
 		log.Fatalf("Error starting redoctober server: %s\n", err)
 	}