new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_busy_lock.h
@@ -0,0 +1,27 @@
+#ifndef _NGX_HTTP_BUSY_LOCK_H_INCLUDED_
+#define _NGX_HTTP_BUSY_LOCK_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+
+typedef struct {
+    char  *busy;
+    int    busy_n;
+
+    int    waiting_n;
+    int    max_waiting;
+
+    int    conn_n;
+    int    max_conn;
+
+    int    timeout;
+
+ /* ngx_mutex_t  mutex; */
+
+} ngx_http_busy_lock_t;
+
+
+#endif /* _NGX_HTTP_BUSY_LOCK_H_INCLUDED_ */