Make HTTP middleware easier to use

appengine/cmd/dm/distributor/tq_handler.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package distributor
 
 import (
         "net/http"
         "net/url"
         "strings"
 
-        "github.com/julienschmidt/httprouter"
         "github.com/luci/luci-go/appengine/tumble"
         "github.com/luci/luci-go/common/logging"
-        "golang.org/x/net/context"
+        "github.com/luci/luci-go/server/router"
 )
 
 const handlerPattern = "/tq/distributor/:cfgName"
 
 func handlerPath(cfgName string) string {
         return strings.Replace(handlerPattern, ":cfgName", url.QueryEscape(cfgName), 1)
 }
 
 // TaskQueueHandler is the http handler that routes taskqueue tasks made with
 // Config.EnqueueTask to a distributor's HandleTaskQueueTask method.
 //
-// This requires that c already have a Registry installed via the WithRegistry
-// method.
-func TaskQueueHandler(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
+// This requires that ctx.Context already have a Registry installed via the
+// WithRegistry method.
+func TaskQueueHandler(ctx *router.Context) {
+        c, rw, r, p := ctx.Context, ctx.Writer, ctx.Request, ctx.Params
         defer r.Body.Close()
 
         cfgName := p.ByName("cfgName")
         dist, _, err := GetRegistry(c).MakeDistributor(c, cfgName)
         if err != nil {
                 logging.Fields{"error": err, "cfg": cfgName}.Errorf(c, "Failed to make distributor")
                 http.Error(rw, "bad distributor", http.StatusBadRequest)
                 return
         }
         notifications, err := dist.HandleTaskQueueTask(r)
@@ skipping 11 matching lines @@
                 }
                 err = tumble.AddToJournal(c, muts...)
                 if err != nil {
                         logging.Fields{"error": err, "cfg": cfgName}.Errorf(c, "Failed to handle notifications")
                         http.Error(rw, "failure to handle notifications", http.StatusInternalServerError)
                         return
                 }
         }
         rw.WriteHeader(http.StatusOK)
 }