From 8d4e9d44995d6f7de5a0b681616ed8241e39ece3 Mon Sep 17 00:00:00 2001
From: John Keiser <john@johnkeiser.com>
Date: Sat, 6 Jun 2015 10:50:02 -0700
Subject: Improve performance of method_missing by not repeatedly sorting and
 calling enabled_handlers (This was causing major slowdown in tests)

---
 lib/chef/resource.rb          | 20 ++++++++++++++++++++
 lib/chef/resource_resolver.rb | 29 +++++++++++++++--------------
 2 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/lib/chef/resource.rb b/lib/chef/resource.rb
index ab955f5454..d74b942e7d 100644
--- a/lib/chef/resource.rb
+++ b/lib/chef/resource.rb
@@ -1088,10 +1088,30 @@ class Chef
       # NOTE: that we do not support unregistering classes as descendents like
       # we used to for LWRP unloading because that was horrible and removed in
       # Chef-12.
+      # @deprecated
+      # @api private
       alias :resource_classes :descendants
+      # @deprecated
+      # @api private
       alias :find_subclass_by_name :find_descendants_by_name
     end
 
+    # @deprecated
+    # @api private
+    # We memoize a sorted version of descendants so that resource lookups don't
+    # have to sort all the things, all the time.
+    # This was causing performance issues in test runs, and probably in real
+    # life as well.
+    @@sorted_descendants = nil
+    def self.sorted_descendants
+      @@sorted_descendants ||= descendants.sort_by { |x| x.to_s }
+    end
+    def self.inherited(other)
+      super
+      @@sorted_descendants = nil
+    end
+
+
     # If an unknown method is invoked, determine whether the enclosing Provider's
     # lexical scope can fulfill the request. E.g. This happens when the Resource's
     # block invokes new_resource.
diff --git a/lib/chef/resource_resolver.rb b/lib/chef/resource_resolver.rb
index 1bd8892239..1eb5e6d840 100644
--- a/lib/chef/resource_resolver.rb
+++ b/lib/chef/resource_resolver.rb
@@ -79,35 +79,36 @@ class Chef
     end
 
     def prioritized_handlers
-      @prioritized_handlers ||=
-        priority_map.list_handlers(node, resource)
+      @prioritized_handlers ||= priority_map.list_handlers(node, resource)
     end
 
     module Deprecated
       # return a deterministically sorted list of Chef::Resource subclasses
+      # @deprecated Now prioritized_handlers does its own work (more efficiently)
       def resources
-        @resources ||= Chef::Resource.descendants
+        Chef::Resource.sorted_descendants
       end
 
-      # this cut looks at if the resource can handle the resource type on the node
+      # A list of all handlers
+      # @deprecated Now prioritized_handlers does its own work
       def enabled_handlers
-        @enabled_handlers ||=
-          resources.select do |klass|
-            klass.provides?(node, resource)
-          end.sort {|a,b| a.to_s <=> b.to_s }
+        resources.select { |klass| klass.provides?(node, resource) }
       end
 
       protected
 
       # If there are no providers for a DSL, we search through the
       def prioritized_handlers
-        @prioritized_handlers ||= super || begin
-          if !enabled_handlers.empty?
-            Chef::Log.deprecation("#{resource} is marked as providing DSL #{resource}, but provides #{resource.inspect} was never called!")
-            Chef::Log.deprecation("In Chef 13, this will break: you must call provides to mark the names you provide, even if you also override provides? yourself.")
+        @prioritized_handlers ||= super ||
+          resources.select do |klass|
+            # Don't bother calling provides? unless it's overriden. We already
+            # know prioritized_handlers
+            if klass.method(:provides?).owner != Chef::Resource && klass.provides?(node, resource)
+              Chef::Log.deprecation("Resources #{provided.join(", ")} are marked as providing DSL #{resource}, but provides #{resource.inspect} was never called!")
+              Chef::Log.deprecation("In Chef 13, this will break: you must call provides to mark the names you provide, even if you also override provides? yourself.")
+              true
+            end
           end
-          enabled_handlers
-        end
       end
     end
     prepend Deprecated
-- 
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