refac: atomic merge, lost-update race, RunPurge cost, duplicated walks

test/seo_data_cleaner_test.go

@@ -283,7 +283,7 @@ func TestSeoDataCleanerCompensationFailuresAreLogged(t *testing.T) {
 		}
 	})
 
-	t.Run("A failed merge logs the body it could not restore", func(t *testing.T) {
+	t.Run("A failed merge rolls the bodies back and logs no compensation", func(t *testing.T) {
 		e := newSeoEnv(t)
 		e.seedBanner(5, "a.png", "same-hash")
 		e.seedBanner(6, "b.png", "same-hash")
@@ -292,14 +292,18 @@ func TestSeoDataCleanerCompensationFailuresAreLogged(t *testing.T) {
 		e.updateArticle(8, func(a *article.Article) { a.Body = e.bodyUsing(6) })
 		e.updateArticle(9, func(a *article.Article) { a.Body = e.bodyUsing(6) })
 		buffer := captureLog(t)
+		bodiesBefore := map[uint32]string{8: e.articles.articles[8].Body, 9: e.articles.articles[9].Body}
 		flaky := &seoFlakyBodyArticles{mockArticleRepo: e.articles}
-		merge := useCases.NewMergeMediaUseCase(e.images, flaky, newMockImageStorage(), newMockVariantFileRepo(), discardRecorder, e.sites, e.authors, newMockContentTypeRepo(), newMockEntryRepo())
+		merge := newTestMergeMedia(e.images, flaky, newMockImageStorage(), newMockVariantFileRepo(), discardRecorder, e.sites, e.authors, newMockContentTypeRepo(), newMockEntryRepo())
 
 		_, err := merge.Merge(t.Context(), 5, []uint32{6})
 
-		if err == nil || !strings.Contains(buffer.String(), "restore article body 8: body write 3 down") {
+		if err == nil || buffer.Len() != 0 {
 			t.Errorf("err %v log %q", err, buffer.String())
 		}
+		if e.articles.articles[8].Body != bodiesBefore[8] || e.articles.articles[9].Body != bodiesBefore[9] {
+			t.Errorf("expected both bodies back to their original text")
+		}
 	})
 }
 
@@ -330,7 +334,7 @@ func TestSeoDataCleanerCaseInsensitiveBodyMatches(t *testing.T) {
 		e := newSeoEnv(t)
 		seed(e)
 		before := e.stored(9)
-		merge := useCases.NewMergeMediaUseCase(e.images, seoCaseInsensitiveBodyArticles{e.articles}, newMockImageStorage(), newMockVariantFileRepo(), discardRecorder, e.sites, e.authors, newMockContentTypeRepo(), newMockEntryRepo())
+		merge := newTestMergeMedia(e.images, seoCaseInsensitiveBodyArticles{e.articles}, newMockImageStorage(), newMockVariantFileRepo(), discardRecorder, e.sites, e.authors, newMockContentTypeRepo(), newMockEntryRepo())
 
 		result, err := merge.Merge(t.Context(), 5, []uint32{6})