Fixing #437. Transactions now check whether graphs are cyclic, with a somewhat-useful error message if they are.

git-svn-id: https://reductivelabs.com/svn/puppet/trunk@2079 980ebf18-57e1-0310-9a29-db15c13687c0

2 files changed, 18 insertions, 0 deletions

diff --git a/lib/puppet/pgraph.rb b/lib/puppet/pgraph.rb
index 393f88449..894a8fe03 100644
--- a/lib/puppet/pgraph.rb
+++ b/lib/puppet/pgraph.rb
@@ -50,6 +50,21 @@ class Puppet::PGraph < GRATR::Digraph
         end
     end
 
+    # Fail in a somewhat informative way if the graph has become cyclic.
+    def check_cycle
+        sorted = topsort()
+        return true if sorted.size == size()
+
+        bad = []
+        vertices.each do |v|
+            bad << v unless sorted.include?(v)
+        end
+
+        raise Puppet::Error, "Found cycle involving %s" % bad.collect do |v|
+            v.to_s
+        end.join(", ")
+    end
+
     # Which resources a given resource depends upon.
     def dependents(resource)
         tree_from_vertex2(resource).keys
diff --git a/lib/puppet/transaction.rb b/lib/puppet/transaction.rb
index b4d4c8512..33874f83e 100644
--- a/lib/puppet/transaction.rb
+++ b/lib/puppet/transaction.rb
@@ -38,6 +38,7 @@ class Transaction
     # Apply all changes for a resource, returning a list of the events
     # generated.
     def apply(resource)
+        resource.info "Applying"
         begin
             changes = resource.evaluate
         rescue => detail
@@ -458,6 +459,8 @@ class Transaction
         # Then splice in the container information
         graph.splice!(@resources, Puppet::Type::Component)
 
+        graph.check_cycle
+
         graph(graph, :expanded_relationships)
         
         return graph