several fixes:
*) do not add event if file was used less than min_uses
*) do not rely upon event to avoid race conditions
*) ngx_open_file_lookup()
diff --git a/src/core/ngx_open_file_cache.h b/src/core/ngx_open_file_cache.h
index 8ef4aea..dd294e7 100644
--- a/src/core/ngx_open_file_cache.h
+++ b/src/core/ngx_open_file_cache.h
@@ -54,6 +54,7 @@
 
     unsigned                 count:24;
     unsigned                 close:1;
+    unsigned                 use_event:1;
 
     unsigned                 is_dir:1;
     unsigned                 is_file:1;