gitea/api: add cooldown to debounce markdown api failures

gitea/apiclient.go

@@ -4,21 +4,27 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
 	"net/url"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"golang.org/x/sync/semaphore"
 )
 
+const MarkdownFailureCooldownSeconds = 3600 // 1 hour
+
 type APIClient struct {
 	urlBase string
 	orgName string
 	token   string
 	apiSem  *semaphore.Weighted
+
+	lastMarkdownFailure atomic.Int64
 }
 
 // NewAPIClient creates a new Gitea API client for a single Gitea organization.
@@ -297,8 +303,22 @@ func (ac *APIClient) topicsForRepo(ctx context.Context, repo string) ([]string,
 	return tr.Topics, nil
 }
 
+var ErrMarkdownCooldown = errors.New("Markdown API was recently not functional")
+
+func (ac *APIClient) checkMarkdownCooldown() error {
+	if ac.lastMarkdownFailure.Load()+MarkdownFailureCooldownSeconds > time.Now().Unix() {
+		return ErrMarkdownCooldown
+	}
+
+	return nil
+}
+
 // renderMarkdown calls the remote Gitea server's own markdown renderer.
 func (ac *APIClient) RenderMarkdown(ctx context.Context, repoName string, body string) ([]byte, error) {
+	if err := ac.checkMarkdownCooldown(); err != nil {
+		return nil, err
+	}
+
 	err := ac.apiSem.Acquire(ctx, 1)
 	if err != nil {
 		return nil, err // e.g. ctx closed
@@ -328,6 +348,7 @@ func (ac *APIClient) RenderMarkdown(ctx context.Context, repoName string, body s
 	defer resp.Body.Close()
 
 	if resp.StatusCode != 200 {
+		ac.lastMarkdownFailure.Store(time.Now().Unix())
 		return nil, fmt.Errorf("HTTP %d", resp.StatusCode)
 	}
 
@@ -336,6 +357,10 @@ func (ac *APIClient) RenderMarkdown(ctx context.Context, repoName string, body s
 
 // renderMarkdownRaw calls the remote Gitea server's own markdown renderer.
 func (ac *APIClient) renderMarkdownRaw(ctx context.Context, body []byte) ([]byte, error) {
+	if err := ac.checkMarkdownCooldown(); err != nil {
+		return nil, err
+	}
+
 	err := ac.apiSem.Acquire(ctx, 1)
 	if err != nil {
 		return nil, err // e.g. ctx closed
@@ -356,6 +381,7 @@ func (ac *APIClient) renderMarkdownRaw(ctx context.Context, body []byte) ([]byte
 	defer resp.Body.Close()
 
 	if resp.StatusCode != 200 {
+		ac.lastMarkdownFailure.Store(time.Now().Unix())
 		return nil, fmt.Errorf("HTTP %d", resp.StatusCode)
 	}
 

page_repository.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"html"
 	"log"
@@ -9,6 +10,8 @@ import (
 	"net/url"
 	"strings"
 
+	"teafolio/gitea"
+
 	"github.com/yuin/goldmark"
 )
 
@@ -59,7 +62,9 @@ func (this *Application) Repopage(w http.ResponseWriter, r *http.Request, repoNa
 
 	readmeHtml, err := this.gitea.RenderMarkdown(ctx, repoName, strings.Join(lines, "\n"))
 	if err != nil {
+		if !errors.Is(err, gitea.ErrMarkdownCooldown) {
 			log.Printf("%s %s: %s", r.Method, r.URL.Path, fmt.Errorf("rendering markdown: %w", err))
+		}
 
 		// Failed to use Gitea's markdown renderer
 		// HTTP 401 (Unauthorized) started happening with this API sometime