new file mode 100644
--- /dev/null
+++ b/src/core/ngx_rbtree.h
@@ -0,0 +1,43 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#ifndef _NGX_RBTREE_H_INCLUDED_
+#define _NGX_RBTREE_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+typedef struct ngx_rbtree_s  ngx_rbtree_t;
+
+struct ngx_rbtree_s {
+   ngx_int_t       key;
+   ngx_rbtree_t   *left;
+   ngx_rbtree_t   *right;
+   ngx_rbtree_t   *parent;
+   char            color;
+};
+
+
+void ngx_rbtree_insert(ngx_rbtree_t **root, ngx_rbtree_t *sentinel,
+                       ngx_rbtree_t *node);
+void ngx_rbtree_delete(ngx_rbtree_t **root, ngx_rbtree_t *sentinel,
+                       ngx_rbtree_t *node);
+
+
+ngx_inline static ngx_rbtree_t *ngx_rbtree_min(ngx_rbtree_t *node,
+                                               ngx_rbtree_t *sentinel)
+{
+   while (node->left != sentinel) {
+       node = node->left;
+   }
+
+   return node;
+}
+
+
+#endif /* _NGX_RBTREE_H_INCLUDED_ */