plugins: the GitHub list waits up to 3s for a repository's https icon fetched the first time (yetone: 非官方插件显示不出来 logo)

RepoIcons starts every fetch, then waits for those not in yet, so the
list's first answer has them; one slower than the wait shows the next
time. The fetch takes fetchPluginIcon before its goroutine starts.

Ran: go test ./internal/provider ./internal/gui; the new test -race
-count=10, and red with a 1ns wait. A sandbox build (fresh HOME, real
GitHub): the first /api/plugins/github answer has all 8 icons the 13
tagged repositories give, screenshot in light and dark.

internal/gui/plugins.go

@@ -281,8 +281,12 @@ func pluginRoutes(mux *http.ServeMux, w Windows) {
 		// each one's own picture as the page can show it, kept here as an
 		// installed plugin's is (a data URI isn't sent on to the page)
 		repos := append([]plugin.Tagged(nil), plugin.TaggedRepos(r.Context())...)
+		said := make([]string, len(repos))
 		for i := range repos {
-			repos[i].Icon = provider.RepoIcon(repos[i].Icon)
+			said[i] = repos[i].Icon
+		}
+		for i, ic := range provider.RepoIcons(said, 3*time.Second) {
+			repos[i].Icon = ic
 		}
 		writeJSON(rw, map[string]any{"repos": repos, "topic": plugin.Topic})
 	})

internal/provider/plugin_icon.go

@@ -32,6 +32,8 @@ var plugIcons struct {
 	from  string // the file they were read from
 	kept  map[string]string
 	tried map[string]time.Time
+	// the URLs being fetched now, each closed once its fetch is over
+	busy map[string]chan struct{}
 }
 
 // fetchPluginIcon fetches an https picture as an import link's is: a
@@ -98,24 +100,72 @@ func pluginOwnIcon(said string) string {
 	if err != nil {
 		return ""
 	}
+	if plugIcons.busy == nil {
+		plugIcons.busy = map[string]chan struct{}{}
+	}
+	done := make(chan struct{})
+	plugIcons.busy[k] = done
+	fetch := fetchPluginIcon
 	go func() {
 		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 		defer cancel()
-		ic, err := fetchPluginIcon(ctx, u)
-		if err != nil {
-			return
-		}
+		ic, err := fetch(ctx, u)
 		plugIcons.Lock()
-		keepPlugIcon(k, ic)
+		if err == nil {
+			keepPlugIcon(k, ic)
+		}
+		delete(plugIcons.busy, k)
 		plugIcons.Unlock()
+		close(done)
 	}()
 	return ""
 }
 
-// RepoIcon is the Icon value of the picture a plugin not installed yet
-// gives in its package.json (a repository tagged magpie-plugin), checked
-// and kept as an installed plugin's is: "" while there is none to show.
-func RepoIcon(said string) string { return pluginOwnIcon(said) }
+// RepoIcons are the Icon values of the pictures plugins not installed yet
+// give in their package.json (repositories tagged magpie-plugin), checked
+// and kept as an installed plugin's are: "" where there is none to show.
+// An https picture not fetched before is waited for up to wait, so the
+// list's first answer has it (yetone: 非官方插件显示不出来 logo); one
+// slower than that shows the next time the list is asked.
+func RepoIcons(said []string, wait time.Duration) []string {
+	out := make([]string, len(said))
+	var busy []chan struct{}
+	for i, s := range said {
+		out[i] = pluginOwnIcon(s)
+		if out[i] == "" && s != "" {
+			sum := sha256.Sum256([]byte(s))
+			plugIcons.Lock()
+			if ch := plugIcons.busy[hex.EncodeToString(sum[:16])]; ch != nil {
+				busy = append(busy, ch)
+			}
+			plugIcons.Unlock()
+		}
+	}
+	if len(busy) == 0 {
+		return out
+	}
+	t := time.NewTimer(wait)
+	defer t.Stop()
+	for _, ch := range busy {
+		select {
+		case <-ch:
+		case <-t.C:
+			return refill(out, said)
+		}
+	}
+	return refill(out, said)
+}
+
+// refill asks again for the pictures not in yet, which those fetched since
+// now have
+func refill(out, said []string) []string {
+	for i, s := range said {
+		if out[i] == "" && s != "" {
+			out[i] = pluginOwnIcon(s)
+		}
+	}
+	return out
+}
 
 // keptPluginIcons are the names of the stored pictures plugins gave, which
 // pruneIcons leaves.

internal/provider/plugin_icon_test.go

@@ -94,3 +94,60 @@ func TestPluginOwnIcon(t *testing.T) {
 		t.Errorf("fetched again: %d", fetched.Load())
 	}
 }
+
+// yetone: 非官方插件显示不出来 logo. A repository's https picture not fetched
+// before is waited for, so the GitHub list's first answer has it; one slower
+// than the wait shows the next time, and the wait ends when it does.
+func TestRepoIconsWaitForFirstFetch(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("USERPROFILE", home)
+	t.Setenv("XDG_CONFIG_HOME", filepath.Join(home, ".config"))
+	t.Setenv("XDG_CACHE_HOME", filepath.Join(home, ".cache"))
+
+	png := []byte("\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR")
+	slow := make(chan struct{})
+	// the fetch left waiting ends with the test
+	t.Cleanup(func() {
+		close(slow)
+		for i := 0; i < 200; i++ {
+			plugIcons.Lock()
+			n := len(plugIcons.busy)
+			plugIcons.Unlock()
+			if n == 0 {
+				return
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+		t.Error("the slow fetch didn't end")
+	})
+	was := fetchPluginIcon
+	t.Cleanup(func() { fetchPluginIcon = was })
+	fetchPluginIcon = func(ctx context.Context, u string) (string, error) {
+		if strings.Contains(u, "slow") {
+			select {
+			case <-slow:
+			case <-ctx.Done():
+			}
+			return "", ctx.Err()
+		}
+		time.Sleep(100 * time.Millisecond)
+		return StoreIcon(png)
+	}
+
+	data := "data:image/png;base64," + base64.StdEncoding.EncodeToString(png)
+	said := []string{"https://gaccode.example/favicon.png", "", data}
+	got := RepoIcons(said, 5*time.Second)
+	if !strings.HasPrefix(got[0], "file:") || got[1] != "" || !strings.HasPrefix(got[2], "file:") {
+		t.Fatalf("first answer = %q", got)
+	}
+
+	start := time.Now()
+	got = RepoIcons([]string{"https://slow.example/icon.png"}, 300*time.Millisecond)
+	if got[0] != "" {
+		t.Fatalf("a fetch never finished = %q", got[0])
+	}
+	if d := time.Since(start); d < 250*time.Millisecond || d > 3*time.Second {
+		t.Fatalf("waited %v for a 300ms wait", d)
+	}
+}