perf: optimize converting releases to feed items (#7221)

- `releasesToFeedItems` is called to convert release structs to feed items, which is then used to render RSS or Atom feeds.
- Optimize the loading of attributes for the releases, introduce `ReleaseList` type which uses caching to load repository and publishers. It also no longer loads release attachments and downloads counts as that is not used in feed items.
- Optimize the composing of meta by introducing caching, this operation is especially slow when the owner is an organization.
- Add unit test (ensures new `LoadAttributes` works correctly).
- Add integration test (ensures that feed output is still as expected).

Loading https://codeberg.org/forgejo/forgejo/releases.rss reduced from ~15s to ~1s. (It is currently is deployed on codeberg.org)

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7221
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

models/repo/release_list.go

@@ -0,0 +1,45 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package repo
+
+import (
+	"context"
+
+	user_model "code.gitea.io/gitea/models/user"
+)
+
+type ReleaseList []*Release
+
+// LoadAttributes loads the repository and publisher for the releases.
+func (r ReleaseList) LoadAttributes(ctx context.Context) error {
+	repoCache := make(map[int64]*Repository)
+	userCache := make(map[int64]*user_model.User)
+
+	for _, release := range r {
+		var err error
+		repo, ok := repoCache[release.RepoID]
+		if !ok {
+			repo, err = GetRepositoryByID(ctx, release.RepoID)
+			if err != nil {
+				return err
+			}
+			repoCache[release.RepoID] = repo
+		}
+		release.Repo = repo
+
+		publisher, ok := userCache[release.PublisherID]
+		if !ok {
+			publisher, err = user_model.GetUserByID(ctx, release.PublisherID)
+			if err != nil {
+				if !user_model.IsErrUserNotExist(err) {
+					return err
+				}
+				publisher = user_model.NewGhostUser()
+			}
+			userCache[release.PublisherID] = publisher
+		}
+		release.Publisher = publisher
+	}
+	return nil
+}

models/repo/release_list_test.go

@@ -0,0 +1,42 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package repo
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReleaseListLoadAttributes(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	releases := ReleaseList{&Release{
+		RepoID:      1,
+		PublisherID: 1,
+	}, &Release{
+		RepoID:      2,
+		PublisherID: 2,
+	}, &Release{
+		RepoID:      1,
+		PublisherID: 2,
+	}, &Release{
+		RepoID:      2,
+		PublisherID: 1,
+	}}
+
+	require.NoError(t, releases.LoadAttributes(t.Context()))
+
+	assert.EqualValues(t, 1, releases[0].Repo.ID)
+	assert.EqualValues(t, 1, releases[0].Publisher.ID)
+	assert.EqualValues(t, 2, releases[1].Repo.ID)
+	assert.EqualValues(t, 2, releases[1].Publisher.ID)
+	assert.EqualValues(t, 1, releases[2].Repo.ID)
+	assert.EqualValues(t, 2, releases[2].Publisher.ID)
+	assert.EqualValues(t, 2, releases[3].Repo.ID)
+	assert.EqualValues(t, 1, releases[3].Publisher.ID)
+}

routers/web/feed/convert.go

@@ -298,14 +298,14 @@ func GetFeedType(name string, req *http.Request) (bool, string, string) {
 	return false, name, ""
 }
 
-// feedActionsToFeedItems convert gitea's Repo's Releases to feeds Item
-func releasesToFeedItems(ctx *context.Context, releases []*repo_model.Release) (items []*feeds.Item, err error) {
-	for _, rel := range releases {
-		err := rel.LoadAttributes(ctx)
-		if err != nil {
+// feedActionsToFeedItems convert repository releases into feed items.
+func releasesToFeedItems(ctx *context.Context, releases repo_model.ReleaseList) (items []*feeds.Item, err error) {
+	if err := releases.LoadAttributes(ctx); err != nil {
 		return nil, err
 	}
 
+	composeCache := make(map[int64]map[string]string)
+	for _, rel := range releases {
 		var title string
 		var content template.HTML
 
@@ -315,13 +315,19 @@ func releasesToFeedItems(ctx *context.Context, releases []*repo_model.Release) (
 			title = rel.Title
 		}
 
+		metas, ok := composeCache[rel.RepoID]
+		if !ok {
+			metas = rel.Repo.ComposeMetas(ctx)
+			composeCache[rel.RepoID] = metas
+		}
+
 		link := &feeds.Link{Href: rel.HTMLURL()}
 		content, err = markdown.RenderString(&markup.RenderContext{
 			Ctx: ctx,
 			Links: markup.Links{
 				Base: rel.Repo.Link(),
 			},
-			Metas: rel.Repo.ComposeMetas(ctx),
+			Metas: metas,
 		}, rel.Note)
 		if err != nil {
 			return nil, err

tests/integration/release_feed_test.go

@@ -0,0 +1,91 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package integration
+
+import (
+	"net/http"
+	"regexp"
+	"testing"
+
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestReleaseFeed(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	normalize := func(body string) string {
+		// Remove port.
+		body = regexp.MustCompile(`localhost:\d+`).ReplaceAllString(body, "localhost")
+		// date is timezone dependent.
+		body = regexp.MustCompile(`<pubDate>.*</pubDate>`).ReplaceAllString(body, "<pubDate></pubDate>")
+		body = regexp.MustCompile(`<updated>.*</updated>`).ReplaceAllString(body, "<updated></updated>")
+		return body
+	}
+	t.Run("RSS feed", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		resp := MakeRequest(t, NewRequest(t, "GET", "/user2/repo1/releases.rss"), http.StatusOK)
+		assert.EqualValues(t, `<?xml version="1.0" encoding="UTF-8"?><rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/">
+  <channel>
+    <title>Releases for user2/repo1</title>
+    <link>http://localhost/user2/repo1/release</link>
+    <description></description>
+    <pubDate></pubDate>
+    <item>
+      <title>pre-release</title>
+      <link>http://localhost/user2/repo1/releases/tag/v1.0</link>
+      <description></description>
+      <content:encoded><![CDATA[<p dir="auto">some text for a pre release</p>
+]]></content:encoded>
+      <author>user2</author>
+      <guid>5: http://localhost/user2/repo1/releases/tag/v1.0</guid>
+      <pubDate></pubDate>
+    </item>
+    <item>
+      <title>testing-release</title>
+      <link>http://localhost/user2/repo1/releases/tag/v1.1</link>
+      <description></description>
+      <author>user2</author>
+      <guid>1: http://localhost/user2/repo1/releases/tag/v1.1</guid>
+      <pubDate></pubDate>
+    </item>
+  </channel>
+</rss>`, normalize(resp.Body.String()))
+	})
+
+	t.Run("Atom feed", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		resp := MakeRequest(t, NewRequest(t, "GET", "/user2/repo1/releases.atom"), http.StatusOK)
+		assert.EqualValues(t, `<?xml version="1.0" encoding="UTF-8"?><feed xmlns="http://www.w3.org/2005/Atom">
+  <title>Releases for user2/repo1</title>
+  <id>http://localhost/user2/repo1/release</id>
+  <updated></updated>
+  <link href="http://localhost/user2/repo1/release"></link>
+  <entry>
+    <title>pre-release</title>
+    <updated></updated>
+    <id>5: http://localhost/user2/repo1/releases/tag/v1.0</id>
+    <content type="html">&lt;p dir=&#34;auto&#34;&gt;some text for a pre release&lt;/p&gt;&#xA;</content>
+    <link href="http://localhost/user2/repo1/releases/tag/v1.0" rel="alternate"></link>
+    <author>
+      <name>user2</name>
+      <email>user2@noreply.example.org</email>
+    </author>
+  </entry>
+  <entry>
+    <title>testing-release</title>
+    <updated></updated>
+    <id>1: http://localhost/user2/repo1/releases/tag/v1.1</id>
+    <link href="http://localhost/user2/repo1/releases/tag/v1.1" rel="alternate"></link>
+    <author>
+      <name>user2</name>
+      <email>user2@noreply.example.org</email>
+    </author>
+  </entry>
+</feed>`, normalize(resp.Body.String()))
+	})
+}