# successfully selected.
prefer_asap = True
- # By default, try to avoid selecting root nodes whenever possible. This
- # helps ensure that the maximimum possible number of soft dependencies
- # have been removed from the graph before their parent nodes have
- # selected. This is especially important when those dependencies are
- # going to be rebuilt by revdep-rebuild or `emerge -e system` after the
- # CHOST has been changed (like when building a stage3 from a stage2).
- accept_root_node = False
-
- # State of prefer_asap and accept_root_node flags for successive
- # iterations that loosen the criteria for node selection.
+ # State of variables for successive iterations that loosen the
+ # criteria for node selection.
#
- # iteration prefer_asap accept_root_node
- # 1 True False
- # 2 False False
- # 3 False True
+ # iteration prefer_asap
+ # 1 True
+ # 2 False
#
- # If no nodes are selected on the 3rd iteration, it is due to
+ # If no nodes are selected on the last iteration, it is due to
# unresolved blockers or circular dependencies.
while not mygraph.empty():
selected_nodes = None
ignore_priority = None
if prefer_asap and asap_nodes:
- """ASAP nodes are merged before their soft deps."""
+ # ASAP nodes are merged before their soft deps. Go ahead and
+ # select root nodes here if necessary, since it's typical for
+ # the parent to have been removed from the graph already.
asap_nodes = [node for node in asap_nodes \
if mygraph.contains(node)]
for node in asap_nodes:
# found a non-root node
selected_nodes = [node]
break
- if not selected_nodes and \
- (accept_root_node or ignore_priority is None):
- # settle for a root node
- selected_nodes = [nodes[0]]
+
if selected_nodes:
break
for ignore_priority in xrange(DepPriority.SOFT,
DepPriority.MEDIUM_SOFT + 1):
for node in nodes:
- if nodes is not asap_nodes and \
- not accept_root_node and \
- not mygraph.parent_nodes(node):
+ if not mygraph.parent_nodes(node):
continue
selected_nodes = set()
if gather_deps(ignore_priority,
prefer_asap = False
continue
- if not selected_nodes and not accept_root_node:
- # Maybe there are only root nodes left, so accept them
- # for the next iteration.
- accept_root_node = True
- continue
-
if selected_nodes and ignore_priority > DepPriority.SOFT:
# Try to merge ignored medium deps as soon as possible.
for node in selected_nodes:
scheduler_graph.add(blocked_pkg, uninst_task,
priority=BlockerDepPriority.instance)
- else:
- # None of the Uninstall tasks are acceptable, so
- # the corresponding blockers are unresolvable.
- # We need to drop an Uninstall task here in order
- # to avoid the circular deps code path, but the
- # blocker will still be counted as an unresolved
- # conflict.
- for node in myblocker_uninstalls.leaf_nodes():
- try:
- mygraph.remove(node)
- except KeyError:
- pass
- else:
- uninst_task = node
- ignored_uninstall_tasks.add(node)
- break
+ # Reset the state variables for leaf node selection and
+ # continue trying to select leaf nodes.
+ prefer_asap = True
+ continue
+
+ if not selected_nodes:
+ # Only select root nodes as a last resort. This case should
+ # only trigger when the graph is nearly empty and the only
+ # remaining nodes are isolated (no parents or children). Since
+ # the nodes must be isolated, ignore_priority is not needed.
+ selected_nodes = get_nodes()
+
+ if not selected_nodes and not myblocker_uninstalls.is_empty():
+ # If possible, drop an uninstall task here in order to avoid
+ # the circular deps code path. The corresponding blocker will
+ # still be counted as an unresolved conflict.
+ uninst_task = None
+ for node in myblocker_uninstalls.leaf_nodes():
+ try:
+ mygraph.remove(node)
+ except KeyError:
+ pass
+ else:
+ uninst_task = node
+ ignored_uninstall_tasks.add(node)
+ break
if uninst_task is not None:
- # After dropping an Uninstall task, reset
- # the state variables for leaf node selection and
+ # Reset the state variables for leaf node selection and
# continue trying to select leaf nodes.
prefer_asap = True
- accept_root_node = False
continue
if not selected_nodes:
raise self._unknown_internal_error()
# At this point, we've succeeded in selecting one or more nodes, so
- # it's now safe to reset the prefer_asap and accept_root_node flags
- # to their default states.
+ # reset state variables for leaf node selection.
prefer_asap = True
- accept_root_node = False
mygraph.difference_update(selected_nodes)
projects / portage.git / commitdiff