Optimize the new --skipfirst code so that in only has to build

a new depgraph one time when there are unsatisfied deps. This
works by recursively traversing the digraph to remove the parent
packages whose deps become unsatisfied when their dependencies are
pruned from the mergelist. (trunk r10512:10514)

svn path=/main/branches/2.1.2/; revision=10515

1 files changed, 37 insertions, 7 deletions

diff --git a/bin/emerge b/bin/emerge
index 72955612f..a1761e7e7 100755
--- a/bin/emerge
+++ b/bin/emerge
@@ -8314,19 +8314,49 @@ def action_build(settings, trees, mtimedb,
 				except depgraph.UnsatisfiedResumeDep, e:
 					if "--skipfirst" not in myopts:
 						raise
-					unsatisfied_parents = set(dep.parent for dep in e.value)
-					pruned_mergelist = []
-					for task in mergelist:
-						if isinstance(task, list) and \
-							tuple(task) in unsatisfied_parents:
+
+					graph = mydepgraph.digraph
+					unsatisfied_parents = dict((dep.parent, dep.parent) \
+						for dep in e.value)
+					traversed_nodes = set()
+					unsatisfied_stack = list(unsatisfied_parents)
+					while unsatisfied_stack:
+						pkg = unsatisfied_stack.pop()
+						if pkg in traversed_nodes:
 							continue
-						pruned_mergelist.append(task)
+						traversed_nodes.add(pkg)
+
+						# If this package was pulled in by a parent
+						# package scheduled for merge, removing this
+						# package may cause the the parent package's
+						# dependency to become unsatisfied.
+						for parent_node in graph.parent_nodes(pkg):
+							if not isinstance(parent_node, Package) \
+								or parent_node.operation != "merge":
+								continue
+							unsatisfied = \
+								graph.child_nodes(parent_node,
+								ignore_priority=DepPriority.SOFT)
+							if pkg in unsatisfied:
+								unsatisfied_parents[parent_node] = parent_node
+								unsatisfied_stack.append(parent_node)
+
+					pruned_mergelist = [x for x in mergelist \
+						if isinstance(x, list) and \
+						tuple(x) not in unsatisfied_parents]
+
+					# It shouldn't happen, but if the size of mergelist
+					# does not decrease for some reason then the loop
+					# will be infinite. Therefore, if that case ever
+					# occurs for some reason, raise the exception to
+					# break out of the loop.
 					if not pruned_mergelist or \
 						len(pruned_mergelist) == len(mergelist):
 						raise
 					mergelist[:] = pruned_mergelist
 					dropped_tasks.update(unsatisfied_parents)
-					del e, unsatisfied_parents
+					del e, graph, traversed_nodes, \
+						unsatisfied_parents, unsatisfied_stack
 					continue
 				else:
 					break