Milo: Add ?limit= support to builders

milo/appengine/buildbucket/html.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 buildbucket
 
 import (
-        "fmt"
         "net/http"
-        "strconv"
 
         "github.com/julienschmidt/httprouter"
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/milo/appengine/settings"
         "github.com/luci/luci-go/milo/common/miloerror"
         "github.com/luci/luci-go/server/templates"
 )
 
 // TODO(nodir): move this value to luci-config.
@@ skipping 24 matching lines @@
         }
 
         builder := p.ByName("builder")
         if builder == "" {
                 return nil, &miloerror.Error{
                         Message: "No builder",
                         Code:    http.StatusBadRequest,
                 }
         }
 
-        // numbuilds is a name of buildbot's query string parameter for specifying
+        // limit is a name of the query string parameter for specifying
         // maximum number of builds to show.
-        // We are retaining the parameter name for user convenience.
-        numBuildsStr := r.FormValue("numbuilds")
-        numBuilds := -1
-        if numBuildsStr != "" {
-                var err error
-                numBuilds, err = strconv.Atoi(numBuildsStr)
-                if err != nil {
-                        return nil, &miloerror.Error{
-                                Message: fmt.Sprintf("numbuilds parameter value %q is not a number: %s", numBuildsStr, err),
-                                Code:    http.StatusBadRequest,
-                        }
-                }
-        }
-
-        result, err := builderImpl(c, server, bucket, builder, numBuilds)
+        limit, err := settings.GetLimit(r)
         if err != nil {
                 return nil, err
         }
+
+        result, err := builderImpl(c, server, bucket, builder, limit)
+        if err != nil {
+                return nil, err
+        }
 
         // Render into the template
         args := &templates.Args{
                 "Builder": result,
         }
         return args, nil
 }