From ab2af4dfcb61b568a9753b97dc55f1b45e3a824e Mon Sep 17 00:00:00 2001
From: Stan Lo <a22301613@yahoo.com.tw>
Date: Thu, 14 Jul 2016 18:38:16 +0800
Subject: Modify LogSubscriber for single partial's cache message.

Implement naive partial caching mechanism.

Add test for LogSubscriber

Use ActionView::Base#log_payload to store log_subscriber's payload, so we can pass cache result into it.

Fixed tests

Remove useless settings

Check if #log_payload exists before calling it. Because other classes also includes CacheHelper but don't have is attribute

Use @log_payload_for_partial_reder instead of #log_payload to carry ActionView's payload.

Update test's hash syntax

Add configuration to enable/disable fragment caching logging

Remove unless test and add new test to ensure cache info won't effect next rendering's log

Move :enable_fragment_cache_logging config from ActionView to ActionPack

Apply new config to tests

Update actionview's changelog

Update configuration guide

Improve actionview's changelog

Refactor PartialRenderer#render and log tests

Mute subscriber's log instead of disabling instrumentation.

Fix typo, remove useless comment and use new hash syntax

Improve actionpack's log_subscriber test

Fix rebase mistake

Apply new config to all caching intstrument actions
---
 actionview/lib/action_view/helpers/cache_helper.rb |  8 +++++-
 actionview/lib/action_view/log_subscriber.rb       | 19 ++++++++++++-
 .../lib/action_view/renderer/partial_renderer.rb   | 32 ++++++++++++----------
 3 files changed, 42 insertions(+), 17 deletions(-)

(limited to 'actionview/lib')

diff --git a/actionview/lib/action_view/helpers/cache_helper.rb b/actionview/lib/action_view/helpers/cache_helper.rb
index 6c3092cc46..b598469d01 100644
--- a/actionview/lib/action_view/helpers/cache_helper.rb
+++ b/actionview/lib/action_view/helpers/cache_helper.rb
@@ -226,7 +226,13 @@ module ActionView
 
       # TODO: Create an object that has caching read/write on it
       def fragment_for(name = {}, options = nil, &block) #:nodoc:
-        read_fragment_for(name, options) || write_fragment_for(name, options, &block)
+        if content = read_fragment_for(name, options)
+          @log_payload_for_partial_render[:cache_hit] = true if defined?(@log_payload_for_partial_render)
+          content
+        else
+          @log_payload_for_partial_render[:cache_hit] = false if defined?(@log_payload_for_partial_render)
+          write_fragment_for(name, options, &block)
+        end
       end
 
       def read_fragment_for(name, options) #:nodoc:
diff --git a/actionview/lib/action_view/log_subscriber.rb b/actionview/lib/action_view/log_subscriber.rb
index 34e1a35dc2..c9f308c2a2 100644
--- a/actionview/lib/action_view/log_subscriber.rb
+++ b/actionview/lib/action_view/log_subscriber.rb
@@ -19,7 +19,16 @@ module ActionView
         message << " (#{event.duration.round(1)}ms)"
       end
     end
-    alias :render_partial :render_template
+
+    def render_partial(event)
+      info do
+        message = "  Rendered #{from_rails_root(event.payload[:identifier])}"
+        message << " within #{from_rails_root(event.payload[:layout])}" if event.payload[:layout]
+        message << " (#{event.duration.round(1)}ms)"
+        message << " #{cache_message(event.payload)}" if event.payload.key?(:cache_hit)
+        message
+      end
+    end
 
     def render_collection(event)
       identifier = event.payload[:identifier] || "templates"
@@ -63,6 +72,14 @@ module ActionView
       end
     end
 
+    def cache_message(payload)
+      if payload[:cache_hit]
+        "[cache hit]"
+      else
+        "[cache miss]"
+      end
+    end
+
   private
 
     def log_rendering_start(payload)
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb
index 1509726a37..92bd0ccf91 100644
--- a/actionview/lib/action_view/renderer/partial_renderer.rb
+++ b/actionview/lib/action_view/renderer/partial_renderer.rb
@@ -308,9 +308,7 @@ module ActionView
       if @collection
         render_collection
       else
-        instrument(:partial) do
-          render_partial
-        end
+        render_partial
       end
     end
 
@@ -331,22 +329,26 @@ module ActionView
       end
 
       def render_partial
-        view, locals, block = @view, @locals, @block
-        object, as = @object, @variable
+        instrument(:partial) do |payload|
+          view, locals, block = @view, @locals, @block
+          object, as = @object, @variable
 
-        if !block && (layout = @options[:layout])
-          layout = find_template(layout.to_s, @template_keys)
-        end
+          view.instance_variable_set(:@log_payload_for_partial_render, payload)
 
-        object = locals[as] if object.nil? # Respect object when object is false
-        locals[as] = object if @has_object
+          if !block && (layout = @options[:layout])
+            layout = find_template(layout.to_s, @template_keys)
+          end
 
-        content = @template.render(view, locals) do |*name|
-          view._layout_for(*name, &block)
-        end
+          object = locals[as] if object.nil? # Respect object when object is false
+          locals[as] = object if @has_object
 
-        content = layout.render(view, locals){ content } if layout
-        content
+          content = @template.render(view, locals) do |*name|
+            view._layout_for(*name, &block)
+          end
+
+          content = layout.render(view, locals){ content } if layout
+          content
+        end
       end
 
     # Sets up instance variables needed for rendering a partial. This method
-- 
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