structuremap/structuremap — pull request #256 by roend83 (2014-05-08 16:54:32+00:00)
Title: Changed construction of BuildPlan to use ReaderWriterLock to fix threading issue that causes NullReferenceException

I ran into a threading issue where StructureMap.Pipeline.Instance.ResolveBuildPlan(Type, Policies) was returning null. It appeared to be caused by a threading problem where the value would change between the check that it wasn't null and when it was returned. This patch introduces a ReaderWriterLockSlim to make sure this doesn't happen.