Make HTTP middleware easier to use

appengine/cmd/milo/buildbot/pubsub.go

Index: appengine/cmd/milo/buildbot/pubsub.go
diff --git a/appengine/cmd/milo/buildbot/pubsub.go b/appengine/cmd/milo/buildbot/pubsub.go
index 3dd09904647f2c09db8605c633b029571b59e1f0..612a0ce899d95fd9f41e1b51cf6874fbfcac687a 100644
--- a/appengine/cmd/milo/buildbot/pubsub.go
+++ b/appengine/cmd/milo/buildbot/pubsub.go
@@ -9,15 +9,14 @@ import (
 	"compress/gzip"
 	"encoding/base64"
 	"encoding/json"
-	"net/http"
 	"time"
 
 	"github.com/luci/gae/service/datastore"
 	"github.com/luci/luci-go/common/clock"
 	"github.com/luci/luci-go/common/iotools"
 	log "github.com/luci/luci-go/common/logging"
+	"github.com/luci/luci-go/server/router"
 
-	"github.com/julienschmidt/httprouter"
 	"golang.org/x/net/context"
 )
 
@@ -139,33 +138,37 @@ func unmarshal(
 }
 
 // PubSubHandler is a webhook that stores the builds coming in from pubsub.
-func PubSubHandler(
-	c context.Context, h http.ResponseWriter, r *http.Request, p httprouter.Params) {
-	msg := pubSubSubscription{}
+func PubSubHandler(ctx *router.Context) {
+	c, h, r := ctx.Context, ctx.Writer, ctx.Request
 	defer r.Body.Close()
+	msg := pubSubSubscription{}
 	dec := json.NewDecoder(r.Body)
 	if err := dec.Decode(&msg); err != nil {
 		log.WithError(err).Errorf(
 			c, "Could not decode message.  %s", err)
 		h.WriteHeader(200) // This is a hard failure, we don't want PubSub to retry.
+		ctx.Abort()
 		return
 	}
 	if msg.Subscription != subName {
 		log.Errorf(
 			c, "Subscription name %s does not match %s", msg.Subscription, subName)
 		h.WriteHeader(200)
+		ctx.Abort()
 		return
 	}
 	bbMsg, err := msg.GetData()
 	if err != nil {
 		log.WithError(err).Errorf(c, "Could not decode message %s", err)
 		h.WriteHeader(200)
+		ctx.Abort()
 		return
 	}
 	builds, master, err := unmarshal(c, bbMsg)
 	if err != nil {
 		log.WithError(err).Errorf(c, "Could not unmarshal message %s", err)
 		h.WriteHeader(200)
+		ctx.Abort()
 		return
 	}
 	log.Infof(c, "There are %d builds and master %s", len(builds), master.Name)
@@ -177,6 +180,7 @@ func PubSubHandler(
 		if build.Master == "" {
 			log.Errorf(c, "Invalid message, missing master name")
 			h.WriteHeader(200)
+			ctx.Abort()
 			return
 		}
 		existingBuild := &buildbotBuild{
@@ -195,6 +199,7 @@ func PubSubHandler(
 			log.WithError(err).Errorf(c, "Could not save build in datastore %s", err)
 			// This is transient, we do want PubSub to retry.
 			h.WriteHeader(500)
+			ctx.Abort()
 			return
 		}
 	}
@@ -206,6 +211,7 @@ func PubSubHandler(
 				c, "Could not save master in datastore %s", err)
 			// This is transient, we do want PubSub to retry.
 			h.WriteHeader(500)
+			ctx.Abort()
 			return
 		}
 	}