Convert the deep merge cache to an ImmutableMash

This makes it so that callers can call the deep merge cache
more or less directly so that we're not hanging onto a weird
Hash-of-ImmutableMashes structure.

Care still needs to be taken to consider the fact that:

- the deep merge cache may not be merged for a given keys since
  it is lazily created, so we need to hit the top level accessor
  once to make sure the key is merged before we access it.

- the top-level "give me it all" case where the path is totally
  empty is still handled by doing a manual deep merge of everything.

Once that is done we can call APIs like read/read!/exist? directly
on the ImmutableMash and have fewer edge cases to deal with.

This has the same perf speedup that the prior approach does and
keeps attribute mangling down to 1% of my runtime on my own cookbooks

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/chef-utils/lib/chef-utils/mash.rb b/chef-utils/lib/chef-utils/mash.rb
index bb48064aa3..14159d175a 100644
--- a/chef-utils/lib/chef-utils/mash.rb
+++ b/chef-utils/lib/chef-utils/mash.rb
@@ -106,6 +106,14 @@ module ChefUtils
       alias_method :regular_update, :update
     end
 
+    unless method_defined?(:regular_clear)
+      alias_method :regular_clear, :clear
+    end
+
+    unless method_defined?(:regular_delete)
+      alias_method :regular_delete, :delete
+    end
+
     # @param key<Object> The key to get.
     def [](key)
       regular_reader(key)