# permissions system. Updating trashed items follows a similar
# (but less complicated) strategy to updating permissions, so it
# may be helpful to look at that first.
- #
ActiveRecord::Base.connection.execute "DROP MATERIALIZED VIEW IF EXISTS materialized_permission_view;"
drop_table :permission_refresh_lock
}
# Merge all permission relationships into a single view. This
- # consists of: groups (projects) owning things, users owning
- # things, users owning themselves, and explicit permission links.
+ # consists of: groups owned by users and projects, users owned
+ # by other users, users have permission on themselves,
+ # and explicit permission links.
#
# A SQL view gets inlined into the query where it is used as a
# subquery. This enables the query planner to inject constraints,
- # so we only look up edges we plan to traverse and avoid a brute
+ # so it only has to look up edges it plans to traverse and avoid a brute
# force query of all edges.
ActiveRecord::Base.connection.execute %{
create view permission_graph_edges as
where links.link_class='permission'
}
- # Code fragment that is used below. This is used to ensure that
- # the permission edge passed into compute_permission_subgraph
- # takes precedence over an existing edge in the "edges" view.
+ # This is used to ensure that the permission edge passed into
+ # compute_permission_subgraph takes replaces the existing edge in
+ # the "edges" view that is about to be removed.
edge_perm = %{
case (edges.edge_id = perm_edge_id)
when true then starting_perm
end
}
- #
# The primary function to compute permissions for a subgraph.
- # This originally was organized somewhat more cleanly, but this
- # ran into performance issues due to the query optimizer not
- # working across function and "with" expression boundaries. So I
- # had to fall back on using string templates for the repeated
- # code. I'm sorry.
+ # Comments on how it works are inline.
+ #
+ # Due to performance issues due to the query optimizer not
+ # working across function and "with" expression boundaries, I
+ # had to fall back on using string templates for repeated code
+ # in order to inline it.
ActiveRecord::Base.connection.execute %{
create or replace function compute_permission_subgraph (perm_origin_uuid varchar(27),
starting_uuid One of 1, 2, 3 for can_read,
can_write, can_manage respectively, or 0 to revoke
permissions.
+
+ perm_edge_id: Identifies the permission edge that is being updated.
+ Changes of ownership, this is starting_uuid.
+ For links, this is the uuid of the link object.
+ This is used to override the edge value in the database
+ with starting_perm. This is necessary when revoking
+ permissions because the update happens before edge is
+ actually removed.
*/
with
/* Starting from starting_uuid, determine the set of objects that