sync: cache image URLs for main homepage performance

gitea/apiclient.go

@@ -68,7 +68,6 @@ func (ac *APIClient) PopulateCommitInfo(ctx context.Context, rr *Repo) error {
 
 func (ac *APIClient) PopulateTopics(ctx context.Context, rr *Repo) error {
 	t, err := ac.topicsForRepo(ctx, rr.Name)
-
 	if err != nil {
 		return err
 	}
@@ -77,6 +76,16 @@ func (ac *APIClient) PopulateTopics(ctx context.Context, rr *Repo) error {
 	return nil
 }
 
+func (ac *APIClient) PopulateImages(ctx context.Context, rr *Repo) error {
+	img, err := ac.ImageFilesForRepo(ctx, rr.Name)
+	if err != nil {
+		return err
+	}
+
+	rr.Images = img
+	return nil
+}
+
 func (ac *APIClient) apiRequest(ctx context.Context, endpoint string, target interface{}) error {
 	err := ac.apiSem.Acquire(ctx, 1)
 	if err != nil {
@@ -248,7 +257,7 @@ func (ac *APIClient) filesInDirectory(ctx context.Context, repo, dir string) ([]
 	return ret, nil
 }
 
-// imageFilesForRepo finds documentation images for the repository.
+// ImageFilesForRepo finds documentation images for the repository.
 // It searches the top-level directory and the dist/ and doc/ subdirectories.
 func (ac *APIClient) ImageFilesForRepo(ctx context.Context, repo string) ([]ReaddirEntry, error) {
 

gitea/types.go

@@ -13,8 +13,10 @@ type Repo struct {
 
 	// NewestCommit is populated via PopulateCommitInfo().
 	NewestCommit time.Time
-	// Topics is populated via topicsForRepo().
+	// Topics is populated via PopulateTopics().
 	Topics []string
+	// Images are populated via PopulateImages().
+	Images []ReaddirEntry
 }
 
 type ContentsResponse struct {

page_imageredir.go

@@ -1,19 +1,22 @@
 package main
 
 import (
-	"fmt"
 	"net/http"
 )
 
 func (this *Application) Bannerpage(w http.ResponseWriter, r *http.Request, repoName string) {
-	ctx := r.Context()
 
-	images, err := this.gitea.ImageFilesForRepo(ctx, repoName)
-	if err != nil {
-		this.internalError(w, r, fmt.Errorf("listing images: %w", err))
+	this.reposMut.RLock()
+	defer this.reposMut.RUnlock()
+
+	ridx, ok := this.reposAlphabeticalOrder[repoName]
+	if !ok {
+		w.Header().Set(`Location`, `/static/no_image.png`)
+		w.WriteHeader(301)
 		return
 	}
 
+	images := this.reposCache[ridx].Images
 	if len(images) == 0 {
 		w.Header().Set(`Location`, `/static/no_image.png`)
 		w.WriteHeader(301)