[EnvironmentCookbookVersionsEndpoint] Add cookbook object cache to request logic

lib/chef_zero/endpoints/environment_cookbook_versions_endpoint.rb

@@ -36,7 +36,7 @@ def post(request)
         end
 
         # Depsolve!
-        solved = depsolve(request, desired_versions.keys, desired_versions, environment_constraints)
+        solved, cookbook_obj_cache = depsolve(request, desired_versions.keys, desired_versions, environment_constraints)
         unless solved
           if @last_missing_dep && !cookbook_names.include?(@last_missing_dep)
             return raise RestErrorResponse.new(412, "No such cookbook: #{@last_missing_dep}")
@@ -50,23 +50,31 @@ def post(request)
 
         result = {}
         solved.each_pair do |name, versions|
-          cookbook = FFI_Yajl::Parser.parse(get_data(request, request.rest_path[0..1] + ["cookbooks", name, versions[0]]))
+          if cookbook_obj_cache.dig(name, versions[0])
+            cookbook = cookbook_obj_cache[name][versions[0]]
+          else
+            cookbook = FFI_Yajl::Parser.parse(get_data(request, request.rest_path[0..1] + ["cookbooks", name, versions[0]]))
+          end
           result[name] = ChefData::DataNormalizer.normalize_cookbook(self, request.rest_path[0..1], cookbook, name, versions[0], request.base_uri, "MIN", false, api_version: request.api_version)
         end
         json_response(200, result)
       end
 
-      def depsolve(request, unsolved, desired_versions, environment_constraints)
+      def depsolve(request, unsolved, desired_versions, environment_constraints, cookbook_obj_cache = nil)
         desired_versions.each do |cb, ver|
           if ver.empty?
             @last_constraint_failure = cb
-            return nil
+            return [nil, nil]
           end
         end
 
         # If everything is already
         solve_for = unsolved[0]
-        return desired_versions unless solve_for
+        return [desired_versions, cookbook_obj_cache] unless solve_for
+
+        # Cache the get_data calls - this saves the need to run the get_data call a second time in #post
+        # Conceptually: cache[cookbook][version] = cookbook_object
+        cookbook_obj_cache ||= {}
 
         # Go through each desired version of this cookbook, starting with the latest,
         # until we find one we can solve successfully with
@@ -77,6 +85,8 @@ def depsolve(request, unsolved, desired_versions, environment_constraints)
 
           # Pick this cookbook, and add dependencies
           cookbook_obj = FFI_Yajl::Parser.parse(get_data(request, request.rest_path[0..1] + ["cookbooks", solve_for, desired_version]))
+          cookbook_obj_cache[solve_for] ||= {}
+          cookbook_obj_cache[solve_for][desired_version] = cookbook_obj
           cookbook_metadata = cookbook_obj["metadata"] || {}
           cookbook_dependencies = cookbook_metadata["dependencies"] || {}
           dep_not_found = false
@@ -100,10 +110,10 @@ def depsolve(request, unsolved, desired_versions, environment_constraints)
           next if dep_not_found
 
           # Depsolve children with this desired version!  First solution wins.
-          result = depsolve(request, new_unsolved, new_desired_versions, environment_constraints)
-          return result if result
+          result, cookbook_obj_cache = depsolve(request, new_unsolved, new_desired_versions, environment_constraints, cookbook_obj_cache)
+          return [result, cookbook_obj_cache] if result
         end
-        nil
+        [nil, nil]
       end
 
       def sort_versions(versions)