Do not re-write generated files that have not changed

CHANGELOG.md

@@ -16,6 +16,11 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   [Eric Amorde](https://github.com/amorde)
   [#6814](https://github.com/CocoaPods/CocoaPods/pull/6814)
 
+* Do not re-write generated files that have not changed  
+  [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
+  [dingjingpisces2015](https://github.com/dingjingpisces2015)
+  [#6825](https://github.com/CocoaPods/CocoaPods/pull/6825)
+
 ##### Bug Fixes
 
 * Integrate test targets to embed frameworks and resources  

lib/cocoapods/installer.rb

@@ -279,10 +279,18 @@ module Pod
     #
     def clean_sandbox
       sandbox.public_headers.implode!
+      target_support_dirs = sandbox.target_support_files_root.children.select(&:directory?)
       pod_targets.each do |pod_target|
         pod_target.build_headers.implode!
+        target_support_dirs.delete(pod_target.support_files_dir)
       end
 
+      aggregate_targets.each do |aggregate_target|
+        target_support_dirs.delete(aggregate_target.support_files_dir)
+      end
+
+      target_support_dirs.each { |dir| FileUtils.rm_rf(dir) }
+
       unless sandbox_state.deleted.empty?
         title_options = { :verbose_prefix => '-> '.red }
         sandbox_state.deleted.each do |pod_name|

lib/cocoapods/installer/xcode/pods_project_generator/aggregate_target_installer.rb

@@ -84,7 +84,7 @@ module Pod
             native_target.build_configurations.each do |configuration|
               path = target.xcconfig_path(configuration.name)
               gen = Generator::XCConfig::AggregateXCConfig.new(target, configuration.name)
-              gen.save_as(path)
+              update_changed_file(gen, path)
               target.xcconfigs[configuration.name] = gen.xcconfig
               xcconfig_file_ref = add_file_to_support_group(path)
               configuration.base_configuration_reference = xcconfig_file_ref
@@ -104,7 +104,7 @@ module Pod
               path = target.bridge_support_path
               headers = native_target.headers_build_phase.files.map { |bf| sandbox.root + bf.file_ref.path }
               generator = Generator::BridgeSupport.new(headers)
-              generator.save_as(path)
+              update_changed_file(generator, path)
               add_file_to_support_group(path)
             end
           end
@@ -120,7 +120,7 @@ module Pod
           def create_copy_resources_script
             path = target.copy_resources_script_path
             generator = Generator::CopyResourcesScript.new(target.resource_paths_by_config, target.platform)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             add_file_to_support_group(path)
           end
 
@@ -136,7 +136,7 @@ module Pod
           def create_embed_frameworks_script
             path = target.embed_frameworks_script_path
             generator = Generator::EmbedFrameworksScript.new(target.framework_paths_by_config)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             add_file_to_support_group(path)
           end
 
@@ -150,7 +150,7 @@ module Pod
               path = generator_class.path_from_basepath(basepath)
               file_accessors = target.pod_targets.map(&:file_accessors).flatten
               generator = generator_class.new(file_accessors)
-              generator.save_as(path)
+              update_changed_file(generator, path)
               add_file_to_support_group(path)
             end
           end

lib/cocoapods/installer/xcode/pods_project_generator/pod_target_installer.rb

@@ -248,7 +248,7 @@ module Pod
                 path.dirname.mkdir unless path.dirname.exist?
                 info_plist_path = path.dirname + "ResourceBundle-#{bundle_name}-#{path.basename}"
                 generator = Generator::InfoPlistFile.new(target, :bundle_package_type => :bndl)
-                generator.save_as(info_plist_path)
+                update_changed_file(generator, info_plist_path)
                 add_file_to_support_group(info_plist_path)
 
                 bundle_target.build_configurations.each do |c|
@@ -279,7 +279,7 @@ module Pod
           def create_xcconfig_file
             path = target.xcconfig_path
             xcconfig_gen = Generator::XCConfig::PodXCConfig.new(target)
-            xcconfig_gen.save_as(path)
+            update_changed_file(xcconfig_gen, path)
             xcconfig_file_ref = add_file_to_support_group(path)
 
             native_target.build_configurations.each do |c|
@@ -302,7 +302,7 @@ module Pod
             target.supported_test_types.each do |test_type|
               path = target.xcconfig_path(test_type.to_s)
               xcconfig_gen = Generator::XCConfig::PodXCConfig.new(target, true)
-              xcconfig_gen.save_as(path)
+              update_changed_file(xcconfig_gen, path)
               xcconfig_file_ref = add_file_to_support_group(path)
 
               target.test_native_targets.each do |test_target|
@@ -326,7 +326,7 @@ module Pod
             pod_targets = [target, *target.test_dependent_targets]
             resource_paths_by_config = { 'Debug' => pod_targets.flat_map(&:resource_paths) }
             generator = Generator::CopyResourcesScript.new(resource_paths_by_config, target.platform)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             add_file_to_support_group(path)
           end
 
@@ -342,7 +342,7 @@ module Pod
             pod_targets = [target, *target.test_dependent_targets]
             framework_paths_by_config = { 'Debug' => pod_targets.flat_map(&:framework_paths) }
             generator = Generator::EmbedFrameworksScript.new(framework_paths_by_config)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             add_file_to_support_group(path)
           end
 
@@ -387,7 +387,7 @@ module Pod
           def create_prefix_header
             path = target.prefix_header_path
             generator = Generator::PrefixHeader.new(target.file_accessors, target.platform)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             add_file_to_support_group(path)
 
             native_target.build_configurations.each do |c|
@@ -473,7 +473,9 @@ module Pod
             return super unless custom_module_map
             path = target.module_map_path
             UI.message "- Copying module map file to #{UI.path(path)}" do
-              FileUtils.cp(custom_module_map, path)
+              unless path.exist? && FileUtils.identical?(custom_module_map, path)
+                FileUtils.cp(custom_module_map, path)
+              end
               add_file_to_support_group(path)
 
               native_target.build_configurations.each do |c|

lib/cocoapods/installer/xcode/pods_project_generator/target_installer.rb

@@ -89,10 +89,44 @@ module Pod
             settings
           end
 
+          # @param [Generator] generator
+          #        the generator to use for generating the content.
+          #
+          # @param [Pathname] path
+          #        the pathname to save the content into.
+          #
+          # Saves the content the provided path unless the path exists and the contents are exactly the same.
+          #
+          # @return [Void]
+          #
+          def update_changed_file(generator, path)
+            if path.exist?
+              generator.save_as(support_files_temp_dir)
+              unless FileUtils.identical?(support_files_temp_dir, path)
+                FileUtils.mv(support_files_temp_dir, path)
+              end
+            else
+              generator.save_as(path)
+            end
+            clean_support_files_temp_dir if support_files_temp_dir.exist?
+          end
+
           # Creates the directory where to store the support files of the target.
           #
           def create_support_files_dir
-            target.support_files_dir.mkdir
+            target.support_files_dir.mkpath
+          end
+
+          # Remove temp file whose store .prefix/config/dummy file.
+          #
+          def clean_support_files_temp_dir
+            support_files_temp_dir.rmtree
+          end
+
+          # @return [String] The temp file path to store temporary files.
+          #
+          def support_files_temp_dir
+            sandbox.target_support_files_dir('generated_files_tmp')
           end
 
           # Creates the Info.plist file which sets public framework attributes
@@ -103,7 +137,7 @@ module Pod
             path = target.info_plist_path
             UI.message "- Generating Info.plist file at #{UI.path(path)}" do
               generator = Generator::InfoPlistFile.new(target)
-              generator.save_as(path)
+              update_changed_file(generator, path)
               add_file_to_support_group(path)
 
               native_target.build_configurations.each do |c|
@@ -126,7 +160,7 @@ module Pod
             UI.message "- Generating module map file at #{UI.path(path)}" do
               generator = Generator::ModuleMap.new(target)
               yield generator if block_given?
-              generator.save_as(path)
+              update_changed_file(generator, path)
               add_file_to_support_group(path)
 
               native_target.build_configurations.each do |c|
@@ -147,7 +181,7 @@ module Pod
             UI.message "- Generating umbrella header at #{UI.path(path)}" do
               generator = Generator::UmbrellaHeader.new(target)
               yield generator if block_given?
-              generator.save_as(path)
+              update_changed_file(generator, path)
 
               # Add the file to the support group and the native target,
               # so it will been added to the header build phase
@@ -169,7 +203,7 @@ module Pod
           def create_dummy_source
             path = target.dummy_source_path
             generator = Generator::DummySource.new(target.label)
-            generator.save_as(path)
+            update_changed_file(generator, path)
             file_reference = add_file_to_support_group(path)
             native_target.source_build_phase.add_file_reference(file_reference)
           end

lib/cocoapods/sandbox.rb

@@ -89,8 +89,8 @@ module Pod
         path = pod_dir(name)
         path.rmtree if path.exist?
       end
-      podspe_path = specification_path(name)
-      podspe_path.rmtree if podspe_path
+      podspec_path = specification_path(name)
+      podspec_path.rmtree if podspec_path
     end
 
     # Prepares the sandbox for a new installation removing any file that will
@@ -98,7 +98,6 @@ module Pod
     #
     def prepare
       FileUtils.rm_rf(headers_root)
-      FileUtils.rm_rf(target_support_files_root)
 
       FileUtils.mkdir_p(headers_root)
       FileUtils.mkdir_p(sources_root)

spec/unit/installer_spec.rb

@@ -276,12 +276,14 @@ module Pod
 
     describe 'Dependencies Resolution' do
       describe 'updating spec repos' do
-        it 'does not updates the repositories by default' do
+        it 'does not update the repositories by default' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
           config.sources_manager.expects(:update).never
           @installer.send(:resolve_dependencies)
         end
 
         it 'updates the repositories if that was requested' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
           @installer.repo_update = true
           config.sources_manager.expects(:update).once
           @installer.send(:resolve_dependencies)
@@ -346,12 +348,16 @@ module Pod
           @analysis_result = Installer::Analyzer::AnalysisResult.new
           @analysis_result.specifications = []
           @analysis_result.sandbox_state = Installer::Analyzer::SpecsState.new
-          @pod_targets = [PodTarget.new([stub('Spec')], [fixture_target_definition], config.sandbox)]
+          @spec = stub(:name => 'Spec')
+          @spec.stubs(:root => @spec)
+          @pod_targets = [PodTarget.new([@spec], [fixture_target_definition], config.sandbox)]
           @installer.stubs(:analysis_result).returns(@analysis_result)
           @installer.stubs(:pod_targets).returns(@pod_targets)
+          @installer.stubs(:aggregate_targets).returns([])
         end
 
         it 'cleans the header stores' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
           config.sandbox.public_headers.expects(:implode!)
           @installer.pod_targets.each do |pods_target|
             pods_target.build_headers.expects(:implode!)
@@ -360,10 +366,61 @@ module Pod
         end
 
         it 'deletes the sources of the removed Pods' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
           @analysis_result.sandbox_state.add_name('Deleted-Pod', :deleted)
           config.sandbox.expects(:clean_pod).with('Deleted-Pod')
           @installer.send(:clean_sandbox)
         end
+
+        it 'deletes the target support file dirs of the removed pod targets' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
+          FileUtils.mkdir_p(@installer.pod_targets.first.support_files_dir)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Spec',
+          ]
+          @installer.stubs(:pod_targets).returns([])
+          @installer.send(:clean_sandbox)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should.be.empty
+        end
+
+        it 'does not delete the target support file dirs for non removed pod targets' do
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
+          FileUtils.mkdir_p(@installer.pod_targets.first.support_files_dir)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Spec',
+          ]
+          @installer.send(:clean_sandbox)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Spec',
+          ]
+        end
+
+        it 'deletes the target support file dirs of the removed aggregate targets' do
+          aggregate_target = AggregateTarget.new(fixture_target_definition('MyApp'), config.sandbox)
+          @installer.stubs(:aggregate_targets).returns([aggregate_target])
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
+          FileUtils.mkdir_p(@installer.aggregate_targets.first.support_files_dir)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Pods-MyApp',
+          ]
+          @installer.stubs(:aggregate_targets).returns([])
+          @installer.send(:clean_sandbox)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should.be.empty
+        end
+
+        it 'does not delete the target support file dirs for non removed aggregate targets' do
+          aggregate_target = AggregateTarget.new(fixture_target_definition('MyApp'), config.sandbox)
+          @installer.stubs(:aggregate_targets).returns([aggregate_target])
+          FileUtils.mkdir_p(config.sandbox.target_support_files_root)
+          FileUtils.mkdir_p(@installer.aggregate_targets.first.support_files_dir)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Pods-MyApp',
+          ]
+          @installer.send(:clean_sandbox)
+          config.sandbox.target_support_files_root.children.map(&:basename).map(&:to_s).should == [
+            'Pods-MyApp',
+          ]
+        end
       end
     end