实现stale cache读取

internal/nodes/http_request_error.go

@@ -1,6 +1,7 @@
 package nodes
 
 import (
+	"github.com/iwind/TeaGo/lists"
 	"github.com/iwind/TeaGo/types"
 	"net/http"
 )
@@ -25,11 +26,24 @@ func (this *HTTPRequest) writeCode(code int) {
 	_, _ = this.writer.Write([]byte(types.String(code) + " " + http.StatusText(code) + ": '" + this.requestFullURL() + "'" + " (Request Id: " + this.requestId + ")"))
 }
 
-func (this *HTTPRequest) write50x(err error, statusCode int) {
+func (this *HTTPRequest) write50x(err error, statusCode int, canTryStale bool) {
 	if err != nil {
 		this.addError(err)
 	}
 
+	// 尝试从缓存中恢复
+	if canTryStale &&
+		this.cacheCanTryStale &&
+		this.web.Cache.Stale != nil &&
+		this.web.Cache.Stale.IsOn &&
+		(len(this.web.Cache.Stale.Status) == 0 || lists.ContainsInt(this.web.Cache.Stale.Status, statusCode)) {
+		ok := this.doCacheRead(true)
+		if ok {
+			return
+		}
+	}
+
+	// 显示自定义页面
 	if this.doPage(statusCode) {
 		return
 	}