node_access_needs_rebuild($rebuild = NULL)
Toggles or reads the value of a flag for rebuilding the node access grants.
When the flag is set, a message is displayed to users with 'access administration pages' permission, pointing to the 'rebuild' confirm form. This can be used as an alternative to direct node_access_rebuild calls, allowing administrators to decide when they want to perform the actual (possibly time consuming) rebuild.
When unsure if the current user is an administrator, node_acc