module ApplicationHelper
+ ALL_PERMISSIONS = {read: true, write: true, manage: true}
+
def current_user
controller.current_user
end
+ def invalidate_permissions_cache
+ Rails.cache.delete_matched(/^groups_for_user_/)
+ end
+
+ def current_groups
+ return {} unless current_user
+ Rails.cache.fetch "groups_for_user_#{current_user.uuid}" do
+ permissions_from = {}
+ todo = {current_user.uuid => true}
+ done = {}
+ while !todo.empty?
+ lookup_uuids = todo.keys
+ lookup_uuids.each do |uuid| done[uuid] = true end
+ todo = {}
+ Link.where('tail_uuid in (?) and link_class = ? and head_kind = ?',
+ lookup_uuids,
+ 'permission',
+ 'orvos#group').each do |link|
+ unless done.has_key? link.head_uuid
+ todo[link.head_uuid] = true
+ end
+ link_permissions = {}
+ case link.name
+ when 'can_read'
+ link_permissions = {read:true}
+ when 'can_write'
+ link_permissions = {read:true,write:true}
+ when 'can_manage'
+ link_permissions = ALL_PERMISSIONS
+ end
+ permissions_from[link.tail_uuid] ||= {}
+ permissions_from[link.tail_uuid][link.head_uuid] ||= {}
+ link_permissions.each do |k,v|
+ permissions_from[link.tail_uuid][link.head_uuid][k] ||= v
+ end
+ end
+ end
+ search_permissions(current_user.uuid, permissions_from)
+ end
+ end
+
+ protected
+
+ def search_permissions(start, graph, merged={}, upstream_mask=nil, upstream_path={})
+ nextpaths = graph[start]
+ return merged if !nextpaths
+ return merged if upstream_path.has_key? start
+ upstream_path[start] = true
+ upstream_mask ||= ALL_PERMISSIONS
+ nextpaths.each do |head, mask|
+ merged[head] ||= {}
+ mask.each do |k,v|
+ merged[head][k] ||= v if upstream_mask[k]
+ end
+ search_permissions(head, graph, merged, upstream_mask.select { |k,v| v && merged[head][k] }, upstream_path)
+ end
+ upstream_path.delete start
+ merged
+ end
+
end
serialize :properties, Hash
before_create :permission_to_attach_to_objects
before_update :permission_to_attach_to_objects
+ after_update :maybe_invalidate_permissions_cache
+ after_create :maybe_invalidate_permissions_cache
+ after_destroy :maybe_invalidate_permissions_cache
attr_accessor :head
attr_accessor :tail
# Default = deny.
false
end
+
+ def maybe_invalidate_permissions_cache
+ if self.link_class == 'permission'
+ # Clearing the entire permissions cache can generate many
+ # unnecessary queries if many active users are not affected by
+ # this change. In such cases it would be better to search cached
+ # permissions for head_uuid and tail_uuid, and invalidate the
+ # cache for only those users. (This would require a browseable
+ # cache.)
+ invalidate_permissions_cache
+ end
+ end
end