Optimize ActiveResource::Base.new(attributes)

* Add performance benchmark similar to ActiveRecord
* Lazily find_or_create_resource_for_collection to not incur the overhead for empty arrays and arrays of primatives
* #duplicable? is faster than inline rescues when the object is not duplicable
* Don't constantly raise and handle NameError, raising is expensive
* Even when a resource is nested inside a module, always look inside the class first for the resource definition so we don't overwrite classes all the time

Before:                                     user     system      total        real
Model.new (instantiation)               0.120000   0.000000   0.120000 (  0.119961)
Nested::Model.new (instantiation)       0.150000   0.010000   0.160000 (  0.151183)
Model.new (setting attributes)         28.540000   0.680000  29.220000 ( 29.271775)
Nested::Model.new (setting attributes) 29.740000   0.580000  30.320000 ( 30.486210)

After:                                        user     system      total        real
Model.new (instantiation)                 0.120000   0.000000   0.120000 (  0.121249)
Nested::Model.new (instantiation)         0.150000   0.010000   0.160000 (  0.152429)
Model.new (setting attributes)           11.480000   0.170000  11.650000 ( 11.656163)
Nested::Model.new (setting attributes)   11.510000   0.210000  11.720000 ( 11.724249)

activeresource/examples/performance.rb

@@ -0,0 +1,70 @@
+require 'rubygems'
+require 'active_resource'
+require 'benchmark'
+
+TIMES = (ENV['N'] || 10_000).to_i
+
+# deep nested resource
+attrs = {
+  :id => 1,
+  :name => 'Luis',
+  :age => 21,
+  :friends => [
+    {
+      :name => 'JK',
+      :age => 24,
+      :colors => ['red', 'green', 'blue'],
+      :brothers => [
+        {
+          :name => 'Mateo',
+          :age => 35,
+          :children => [{ :name => 'Edith', :age => 5 }, { :name => 'Martha', :age => 4 }]
+        },
+        {
+          :name => 'Felipe',
+          :age => 33,
+          :children => [{ :name => 'Bryan', :age => 1 }, { :name => 'Luke', :age => 0 }]
+        }
+      ]
+    },
+    {
+      :name => 'Eduardo',
+      :age => 20,
+      :colors => [],
+      :brothers => [
+        {
+          :name => 'Sebas',
+          :age => 23,
+          :children => [{ :name => 'Andres', :age => 0 }, { :name => 'Jorge', :age => 2 }]
+        },
+        {
+          :name => 'Elsa',
+          :age => 19,
+          :children => [{ :name => 'Natacha', :age => 1 }]
+        },
+        {
+          :name => 'Milena',
+          :age => 16,
+          :children => []
+        }
+      ]
+    }
+  ]
+}
+
+class Customer < ActiveResource::Base
+  self.site = "http://37s.sunrise.i:3000"
+end
+
+module Nested
+  class Customer < ActiveResource::Base
+    self.site = "http://37s.sunrise.i:3000"
+  end
+end
+
+Benchmark.bm(40) do |x|
+  x.report('Model.new (instantiation)')              { TIMES.times { Customer.new } }
+  x.report('Nested::Model.new (instantiation)')      { TIMES.times { Nested::Customer.new } }
+  x.report('Model.new (setting attributes)')         { TIMES.times { Customer.new attrs } }
+  x.report('Nested::Model.new (setting attributes)') { TIMES.times { Nested::Customer.new attrs } }
+end

activeresource/lib/active_resource/base.rb

@@ -1239,9 +1239,10 @@ module ActiveResource
         @attributes[key.to_s] =
           case value
             when Array
-              resource = find_or_create_resource_for_collection(key)
+              resource = nil
               value.map do |attrs|
                 if attrs.is_a?(Hash)
+                  resource ||= find_or_create_resource_for_collection(key)
                   resource.new(attrs)
                 else
                   attrs.duplicable? ? attrs.dup : attrs
@@ -1251,7 +1252,7 @@ module ActiveResource
               resource = find_or_create_resource_for(key)
               resource.new(value)
             else
-              value.dup rescue value
+              value.duplicable? ? value.dup : value
           end
       end
       self
@@ -1367,36 +1368,44 @@ module ActiveResource
       end
 
       # Tries to find a resource in a non empty list of nested modules
-      # Raises a NameError if it was not found in any of the given nested modules
+      # if it fails, then the resource is created
-      def find_resource_in_modules(resource_name, module_names)
+      def find_or_create_resource_in_modules(resource_name, module_names)
         receiver = Object
         namespaces = module_names[0, module_names.size-1].map do |module_name|
           receiver = receiver.const_get(module_name)
         end
         const_args = RUBY_VERSION < "1.9" ? [resource_name] : [resource_name, false]
         if namespace = namespaces.reverse.detect { |ns| ns.const_defined?(*const_args) }
-          return namespace.const_get(*const_args)
+          namespace.const_get(*const_args)
         else
-          raise NameError
+          create_resource_for(resource_name)
         end
       end
 
       # Tries to find a resource for a given name; if it fails, then the resource is created
       def find_or_create_resource_for(name)
         resource_name = name.to_s.camelize
-        ancestors = self.class.name.split("::")
+
-        if ancestors.size > 1
-          find_resource_in_modules(resource_name, ancestors)
-        else
-          self.class.const_get(resource_name)
-        end
-      rescue NameError
         const_args = RUBY_VERSION < "1.9" ? [resource_name] : [resource_name, false]
         if self.class.const_defined?(*const_args)
-          resource = self.class.const_get(*const_args)
+          self.class.const_get(*const_args)
         else
-          resource = self.class.const_set(resource_name, Class.new(ActiveResource::Base))
+          ancestors = self.class.name.split("::")
+          if ancestors.size > 1
+            find_or_create_resource_in_modules(resource_name, ancestors)
+          else
+            if Object.const_defined?(*const_args)
+              Object.const_get(*const_args)
+            else
+              create_resource_for(resource_name)
+            end
+          end
         end
+      end
+
+      # Create and return a class definition for a resource inside the current resource
+      def create_resource_for(resource_name)
+        resource = self.class.const_set(resource_name, Class.new(ActiveResource::Base))
         resource.prefix = self.class.prefix
         resource.site   = self.class.site
         resource