Make HTTP middleware easier to use

appengine/tumble/service.go

 // Copyright 2015 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 tumble
 
 import (
         "fmt"
         "net/http"
         "strconv"
         "sync"
         "time"
 
-        "github.com/julienschmidt/httprouter"
         "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/info"
         "github.com/luci/luci-go/appengine/gaemiddleware"
         "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/parallel"
+        "github.com/luci/luci-go/server/router"
         "golang.org/x/net/context"
 )
 
 const transientHTTPHeader = "X-LUCI-Tumble-Transient"
 
 // Service is an instance of a Tumble service. It installs its handlers into an
 // HTTP router and services Tumble request tasks.
 type Service struct {
         // Middleware is an optional function which allows your application to add
         // application-specific resources to the context used by ProcessShardHandler.
         //
         // Context will already be setup with BaseProd.
         Middleware func(context.Context) context.Context
 
         // Namespaces is a function that returns the datastore namespaces that Tumble
         // will poll.
         //
         // If nil, Tumble will be executed against all namespaces registered in the
         // datastore.
         Namespaces func(context.Context) ([]string, error)
 }
 
 // InstallHandlers installs http handlers.
-func (s *Service) InstallHandlers(r *httprouter.Router) {
+func (s *Service) InstallHandlers(r *router.Router) {
+        mc := append(gaemiddleware.BaseProd(), gaemiddleware.RequireCron)
         // GET so that this can be invoked from cron
-        r.GET(fireAllTasksURL,
-                gaemiddleware.BaseProd(gaemiddleware.RequireCron(s.FireAllTasksHandler)))
-
-        r.POST(processShardPattern,
-                gaemiddleware.BaseProd(gaemiddleware.RequireTaskQueue(baseName, s.ProcessShardHandler)))
+        r.GET(fireAllTasksURL, mc, s.FireAllTasksHandler)
+        r.POST(processShardPattern, append(mc, gaemiddleware.RequireTaskQueue(baseName)), s.ProcessShardHandler)
 }
 
-// FireAllTasksHandler is a http handler suitable for installation into
-// a httprouter. It expects `logging` and `luci/gae` services to be installed
-// into the context.
+// FireAllTasksHandler is an HTTP handler that expects `logging` and `luci/gae`
+// services to be installed into the context.
 //
 // FireAllTasksHandler verifies that it was called within an Appengine Cron
 // request, and then invokes the FireAllTasks function.
-func (s *Service) FireAllTasksHandler(c context.Context, rw http.ResponseWriter, r *http.Request, _ httprouter.Params) {
-        if err := s.FireAllTasks(c); err != nil {
-                rw.WriteHeader(http.StatusInternalServerError)
-                fmt.Fprintf(rw, "fire_all_tasks failed: %s", err)
+func (s *Service) FireAllTasksHandler(c *router.Context) {
+        if err := s.FireAllTasks(c.Context); err != nil {
+                c.Writer.WriteHeader(http.StatusInternalServerError)
+                fmt.Fprintf(c.Writer, "fire_all_tasks failed: %s", err)
         } else {
-                rw.Write([]byte("ok"))
+                c.Writer.Write([]byte("ok"))
         }
 }
 
 // FireAllTasks searches for work in all namespaces, and fires off a process
 // task for any shards it finds that have at least one Mutation present to
 // ensure that no work languishes forever. This may not be needed in
 // a constantly-loaded system with good tumble key distribution.
 func (s *Service) FireAllTasks(c context.Context) error {
         cfg := getConfig(c)
         shards := make(map[taskShard]struct{}, cfg.NumShards)
@@ skipping 95 matching lines @@
                         return
                 }
         } else {
                 // Namespacing is disabled, use a single empty string. Process will
                 // interpret this as a signal to not use namesapces.
                 namespaces = []string{""}
         }
         return
 }
 
-// ProcessShardHandler is a http handler suitable for installation into
-// a httprouter. It expects `logging` and `luci/gae` services to be installed
-// into the context.
+// ProcessShardHandler is an HTTP handler that expects `logging` and `luci/gae`
+// services to be installed into the context.
 //
 // ProcessShardHandler verifies that its being run as a taskqueue task and that
 // the following parameters exist and are well-formed:
 //   * timestamp: decimal-encoded UNIX/UTC timestamp in seconds.
 //   * shard_id: decimal-encoded shard identifier.
 //
 // ProcessShardHandler then invokes ProcessShard with the parsed parameters.
-func (s *Service) ProcessShardHandler(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func (s *Service) ProcessShardHandler(ctx *router.Context) {
+        c, rw, p := ctx.Context, ctx.Writer, ctx.Params
+
         if s.Middleware != nil {
                 c = s.Middleware(c)
         }
 
         tstampStr := p.ByName("timestamp")
         sidStr := p.ByName("shard_id")
 
         tstamp, err := strconv.ParseInt(tstampStr, 10, 64)
         if err != nil {
                 logging.Errorf(c, "bad timestamp %q", tstampStr)
@@ skipping 54 matching lines @@
         }
 
         namespaces := make([]string, 0, len(namespaceKeys))
         for _, nk := range namespaceKeys {
                 if ns := nk.StringID(); ns != "" {
                         namespaces = append(namespaces, ns)
                 }
         }
         return namespaces, nil
 }