实现缓存策略最大容量

internal/nodes/http_request_cache.go

@@ -147,5 +147,6 @@ func (this *HTTPRequest) doCacheRead() (shouldStop bool) {
 		return
 	}
 
+	this.cacheRef = nil // 终止读取不再往下传递
 	return true
 }

internal/nodes/http_writer.go

@@ -114,6 +114,7 @@ func (this *HTTPWriter) Write(data []byte) (n int, err error) {
 			_, err = this.cacheWriter.Write(data)
 			if err != nil {
 				_ = this.cacheWriter.Discard()
+				this.cacheWriter = nil
 				logs.Println("write cache failed: " + err.Error())
 			}
 		}