This mail is part 2 in a series regarding the conflict information
storage (see [1] for part 1).
The current Plan (as denoted in both wc-metadata.sql and the
conflict-storage notes) is to store conflict information in the ACTUAL
node. This works fine (and is currently being done on trunk), but
seems to break an assumed invariant that every node will also have an
entry in NODES. The docs in wc-metadata.sql state that "A NODES row
must exist if this node exists, but an ACTUAL_NODE row can exist on
its own if it is just recording info on a non-present node - a tree
conflict or a changelist, for example." So in theory we allow ACTAUL
nodes with conflict info without a NODE entry, but not in practice.
One of the places this bites us is when retrieving children. Child
nodes which are victims of a conflict should be returned as part of
the child list APIs (which ultimately call
libsvn_wc/wc_db.c:gather_children()). Those APIs currently only look
in NODES to find children, without tacking on the conflict victims
embedded in ACTUAL.tree_conflict_data. In crafting a patch to do
this, I run into various places in wc_db where a NODE is assumed if an
ACTUAL node exists.
For instance, I'd like to rewrite
libsvn_client/commit_util.c:bail_on_tree_conflicted_children() so that
it iterates over the children of the directory in question, rather
than use the (soon-to-disappear) "give me all the tree conflict
children on this node" API. However, if conflict victims aren't
returned as part of gather_children(), that API has no way of knowing
about those children who exist only as conflict victims. I believe
there are other reasons to include conflicted children in the child
lists as well.
In the end, I'm not really sure what the best solution is, or how to
get there. I've thought about the possibility of having a NODE with
op_depth=-1 for nodes who only have an ACTUAL node, if only to satisfy
the "ACTUAL must have NODE" invariant. Any other comments or thought
are welcome.
-Hyrum
[1] http://svn.haxx.se/dev/archive-2010-10/0392.shtml
Received on 2010-10-26 23:49:12 CEST