Pre-compiling regexp to make JSONP a bit faster

Author: paulbellamy

jsonp.go

@@ -6,11 +6,13 @@ import (
 	"strings"
 )
 
+var jsonp_valid_callback_matcher *regexp.Regexp = regexp.MustCompile("^[a-zA-Z_$][a-zA-Z_0-9$]*([.]?[a-zA-Z_$][a-zA-Z_0-9$]*)*$")
+
 func JSONP(env Env, app App) (Status, Headers, Body) {
 	callback := env.Request().FormValue("callback")
 
 	if callback != "" {
-		if matched, err := regexp.MatchString("^[a-zA-Z_$][a-zA-Z_0-9$]*([.]?[a-zA-Z_$][a-zA-Z_0-9$]*)*$", callback); !matched || err != nil {
+		if !jsonp_valid_callback_matcher.MatchString(callback) {
 			return 400, Headers{"Content-Type": []string{"text/plain"}, "Content-Length": []string{"11"}}, "Bad Request"
 		}
 	}

jsonp_test.go

@@ -161,3 +161,51 @@ func BenchmarkJSONP(b *testing.B) {
 	}
 	b.StopTimer()
 }
+
+func BenchmarkNonJSONP(b *testing.B) {
+	b.StopTimer()
+
+	nonJsonpStack := new(Stack)
+	nonJsonpStack.Middleware(JSONP)
+	nonJsonpApp := nonJsonpStack.Compile(nonJsonServer)
+
+	request, _ := http.NewRequest("GET", "http://localhost:3000/?callback=parseResponse", nil)
+
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+    nonJsonpApp(Env{"mango.request": &Request{request}})
+	}
+	b.StopTimer()
+}
+
+func BenchmarkJSONPNoCallback(b *testing.B) {
+	b.StopTimer()
+
+	jsonpStack := new(Stack)
+	jsonpStack.Middleware(JSONP)
+	jsonpApp := jsonpStack.Compile(jsonServer)
+
+	request, _ := http.NewRequest("GET", "http://localhost:3000/", nil)
+
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		jsonpApp(Env{"mango.request": &Request{request}})
+	}
+	b.StopTimer()
+}
+
+func BenchmarkJSONPInvalidCallback(b *testing.B) {
+	b.StopTimer()
+
+	jsonpStack := new(Stack)
+	jsonpStack.Middleware(JSONP)
+	jsonpApp := jsonpStack.Compile(jsonServer)
+
+	request, _ := http.NewRequest("GET", "http://localhost:3000/?callback=invalid(callback)", nil)
+
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		jsonpApp(Env{"mango.request": &Request{request}})
+	}
+	b.StopTimer()
+}