Milo: Extract the rietveld information from buildbot.

appengine/cmd/milo/buildbot/build.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 buildbot
 
 import (
         "encoding/json"
         "fmt"
         "io/ioutil"
@@ skipping 323 matching lines @@
                         Repo:        c.Repository,
                         Revision:    c.Revision,
                         Description: c.Comments,
                         Title:       strings.Split(c.Comments, "\n")[0],
                         File:        files,
                 })
         }
         return
 }
 
+// sourcestamp extracts the source stamp from various parts of a buildbot build,
+// including the properties.
+func sourcestamp(c context.Context, b *buildbotBuild) *resp.SourceStamp {
+        ss := &resp.SourceStamp{}
+        rietveld := ""
+        issue := int64(-1)
+        // TODO(hinoka): Gerrit URLs.
+        for _, prop := range b.Properties {
+                key := prop[0].(string)

[nodir, 2016/06/28 21:44:24]

please add a comment to buildbotBuild.Properties that each propetry is a slice
of [propertyName, value, source] where source is optional and where propertyName
and source (if present) are always a string.

otherwise it looks like this will panic too

in general I wish there was a struct buildbotProperty that implements
json.Unmarshaler https://godoc.org/encoding/json#Unmarshaler
this way our code would remain type-safe

[Ryan Tseng, 2016/06/28 21:49:31]

Done.

+                value := prop[1]
+                switch key {
+                case "rietveld":
+                        if v, ok := value.(string); ok {
+                                rietveld = v
+                        } else {
+                                log.Warningf(c, "Field rietveld is not a string: %#v", value)
+                        }
+                case "issue":
+                        if v, ok := value.(float64); ok {
+                                issue = int64(v)
+                        } else {
+                                log.Warningf(c, "Field issue is not a float: %#v", value)
+                        }
+
+                case "got_revision":
+                        if v, ok := value.(string); ok {
+                                ss.Revision = v
+                        } else {
+                                log.Warningf(c, "Field got_revision is not a string: %#v", value)
+                        }
+
+                }
+        }
+        if issue != -1 {
+                if rietveld != "" {
+                        rietveld = strings.TrimRight(rietveld, "/")
+                        ss.Changelist = &resp.Link{
+                                Label: fmt.Sprintf("Issue %d", issue),
+                                URL:   fmt.Sprintf("%s/%d", rietveld, issue),
+                        }
+                } else {
+                        log.Warningf(c, "Found issue but not rietveld property.")
+                }
+        }
+        return ss
+}
+
 func getDebugBuild(c context.Context, builder, buildNum string) (*buildbotBuild, error) {
         fname := fmt.Sprintf("%s.%s.json", builder, buildNum)
         path := filepath.Join("testdata", "buildbot", fname)
         raw, err := ioutil.ReadFile(path)
         if err != nil {
                 return nil, err
         }
         b := &buildbotBuild{}
         return b, json.Unmarshal(raw, b)
 }
 
 // build fetches a buildbot build and translates it into a miloBuild.
 func build(c context.Context, master, builder, buildNum string) (*resp.MiloBuild, error) {
         var b *buildbotBuild
         var err error
         if master == "debug" {
                 b, err = getDebugBuild(c, builder, buildNum)
         } else {
                 b, err = getBuild(c, master, builder, buildNum)
         }
         if err != nil {
                 return nil, err
         }
 
+        // TODO(hinoka): Do all fields concurrently.
         return &resp.MiloBuild{
+                SourceStamp:   sourcestamp(c, b),
                 Summary:       summary(b),
                 Components:    components(b),
                 PropertyGroup: properties(b),
                 Blame:         blame(b),
         }, nil
 }