cmd/gerritbot: post proper display name of message author to GitHub

Gerrit's NoteDB git-based metadata format changed recently to display
"Gerrit User 1234" as the display name for meta commit authors. Use
the Gerrit REST API to retrieve the proper display name and cache the
result to prevent superfluous API calls.

Also updates the maintner doc for the Author property of GerritMessage
to reflect NoteDB's format.

Fixes golang/go#28663

Change-Id: I549474ad139e48c736d715414e82b6db83a9fdf3
Reviewed-on: https://go-review.googlesource.com/c/148560
Reviewed-by: Brad Fitzpatrick <[email protected]>

Author: andybons

cmd/gerritbot/gerritbot.go

@@ -21,6 +21,7 @@ import (
 	"os/user"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -246,15 +247,19 @@ type bot struct {
 	// CLs that have been created/updated on Gerrit for GitHub PRs but are not yet
 	// reflected in the maintner corpus yet.
 	pendingCLs map[string]string // GitHub owner/repo#n -> Commit message from PR
+
+	// Cache of Gerrit Account IDs to AccountInfo structs.
+	cachedGerritAccounts map[int]*gerrit.AccountInfo // 1234 -> Detailed Account Info
 }
 
 func newBot(githubClient *github.Client, gerritClient *gerrit.Client) *bot {
 	return &bot{
-		githubClient: githubClient,
-		gerritClient: gerritClient,
-		importedPRs:  map[string]*maintner.GerritCL{},
-		pendingCLs:   map[string]string{},
-		cachedPRs:    map[string]*cachedPullRequest{},
+		githubClient:         githubClient,
+		gerritClient:         gerritClient,
+		importedPRs:          map[string]*maintner.GerritCL{},
+		pendingCLs:           map[string]string{},
+		cachedPRs:            map[string]*cachedPullRequest{},
+		cachedGerritAccounts: map[int]*gerrit.AccountInfo{},
 	}
 }
 
@@ -371,7 +376,7 @@ func prShortLink(pr *github.PullRequest) string {
 // imported. If the Gerrit change associated with a PR has been merged, the PR
 // is closed. Those that have no associated open or merged Gerrit changes will
 // result in one being created.
-// b's RWMutex read-write lock must be held.
+// b.RWMutex must be Lock'ed.
 func (b *bot) processPullRequest(ctx context.Context, pr *github.PullRequest) error {
 	log.Printf("Processing PR %s ...", pr.GetHTMLURL())
 	shortLink := prShortLink(pr)
@@ -428,24 +433,72 @@ func (b *bot) processPullRequest(ctx context.Context, pr *github.PullRequest) er
 	return nil
 }
 
+// gerritMessageAuthorID returns the Gerrit Account ID of the author of m.
+func gerritMessageAuthorID(m *maintner.GerritMessage) (int, error) {
+	email := m.Author.Email()
+	if strings.Index(email, "@") == -1 {
+		return -1, fmt.Errorf("message author email %q does not contain '@' character", email)
+	}
+	i, err := strconv.Atoi(strings.Split(email, "@")[0])
+	if err != nil {
+		return -1, fmt.Errorf("strconv.Atoi: %v (email: %q)", err, email)
+	}
+	return i, nil
+}
+
+// gerritMessageAuthorName returns a message author's display name. To prevent a
+// thundering herd of redundant comments created by posting a different message
+// via postGitHubMessageNoDup in syncGerritCommentsToGitHub, it will only return
+// the correct display name for messages posted after a hard-coded date.
+// b.RWMutex must be Lock'ed.
+func (b *bot) gerritMessageAuthorName(ctx context.Context, m *maintner.GerritMessage) (string, error) {
+	t := time.Date(2018, time.November, 9, 0, 0, 0, 0, time.UTC)
+	if m.Date.Before(t) {
+		return m.Author.Name(), nil
+	}
+	id, err := gerritMessageAuthorID(m)
+	if err != nil {
+		return "", fmt.Errorf("gerritMessageAuthorID: %v", err)
+	}
+	account := b.cachedGerritAccounts[id]
+	if account != nil {
+		return account.Name, nil
+	}
+	ai, err := b.gerritClient.GetAccountInfo(ctx, strconv.Itoa(id))
+	if err != nil {
+		return "", fmt.Errorf("b.gerritClient.GetAccountInfo: %v", err)
+	}
+	b.cachedGerritAccounts[id] = &ai
+	return ai.Name, nil
+}
+
+// b.RWMutex must be Lock'ed.
 func (b *bot) syncGerritCommentsToGitHub(ctx context.Context, pr *github.PullRequest, cl *maintner.GerritCL) error {
 	if *dryRun {
 		log.Printf("[dry run] would sync Gerrit comments to %v", prShortLink(pr))
 		return nil
 	}
 	repo := pr.GetBase().GetRepo()
 	for _, m := range cl.Messages {
-		if m.Author.Email() == cl.Owner().Email() {
+		id, err := gerritMessageAuthorID(m)
+		if err != nil {
+			return fmt.Errorf("gerritMessageAuthorID: %v", err)
+		}
+		if id == cl.OwnerID() {
 			continue
 		}
+		authorName, err := b.gerritMessageAuthorName(ctx, m)
+		if err != nil {
+			return fmt.Errorf("b.gerritMessageAuthorName: %v", err)
+		}
 		msg := fmt.Sprintf(`Message from %s:
 
 %s
 
 ---
 Please don’t reply on this GitHub thread. Visit [golang.org/cl/%d](https://go-review.googlesource.com/c/%s/+/%d#message-%s).
 After addressing review feedback, remember to [publish your drafts](https://github.com/golang/go/wiki/GerritBot#i-left-a-reply-to-a-comment-in-gerrit-but-no-one-but-me-can-see-it)!`,
-			m.Author.Name(), m.Message, cl.Number, cl.Project.Project(), cl.Number, m.Meta.Hash.String())
+			authorName, m.Message, cl.Number, cl.Project.Project(), cl.Number, m.Meta.Hash.String())
 		if err := b.postGitHubMessageNoDup(ctx, repo.GetOwner().GetLogin(), repo.GetName(), pr.GetNumber(), msg); err != nil {
 			return fmt.Errorf("postGitHubMessageNoDup: %v", err)
 		}
@@ -696,7 +749,7 @@ func reposRoot() string {
 }
 
 // getFullPR retrieves a Pull Request via GitHub’s API.
-// b's RWMutex read-write lock must be held.
+// b.RWMutex must be Lock'ed.
 func (b *bot) getFullPR(ctx context.Context, owner, repo string, number int) (*github.PullRequest, error) {
 	shortLink := githubShortLink(owner, repo, number)
 	cpr := b.cachedPRs[shortLink]

maintner/gerrit.go

@@ -335,9 +335,9 @@ type GerritMessage struct {
 	// the git commit).
 	Date time.Time
 
-	// Author returns the author of the commit. This takes the form "Kevin Burke
-	// <13437@62eb7196-b449-3ce5-99f1-c037f21e1705>", where the number before
-	// the '@' sign is your Gerrit user ID, and the UUID after the '@' sign
+	// Author returns the author of the commit. This takes the form "Gerrit User
+	// 13437 <13437@62eb7196-b449-3ce5-99f1-c037f21e1705>", where the number
+	// before the '@' sign is your Gerrit user ID, and the UUID after the '@' sign
 	// seems to be the same for all commits for the same Gerrit server, across
 	// projects.
 	//