Add caching debug info to better spot volatile cache keys that need i…

…mproving

lib/graphiti.rb

@@ -185,6 +185,7 @@ def self.cache
 require "graphiti/serializer"
 require "graphiti/query"
 require "graphiti/debugger"
+require "graphiti/util/cache_debug"
 
 if defined?(ActiveRecord)
   require "graphiti/adapters/active_record"

lib/graphiti/debugger.rb

@@ -98,10 +98,29 @@ def on_render(name, start, stop, id, payload)
           took = ((stop - start) * 1000.0).round(2)
           logs << [""]
           logs << ["=== Graphiti Debug", :green, true]
-          logs << if payload[:proxy]&.cached? && Graphiti.config.cache_rendering?
-            ["Rendering (cached):", :green, true]
+          if payload[:proxy]&.cached? && Graphiti.config.cache_rendering?
+            logs << ["Rendering (cached):", :green, true]
+
+            Graphiti::Util::CacheDebug.new(payload[:proxy]).analyze do |cache_debug|
+              logs << ["Cache key for #{cache_debug.name}", :blue, true]
+              if cache_debug.volatile?
+                logs << [" \\_ volatile | Request count: #{cache_debug.request_count} | Hit count: #{cache_debug.hit_count}", :red, true]
+              else
+                logs << [" \\_   stable | Request count: #{cache_debug.request_count} | Hit count: #{cache_debug.hit_count}", :blue, true]
+              end
+
+              if cache_debug.changed_key?
+                logs << [" [x] cache key changed #{cache_debug.last_version[:etag]} -> #{cache_debug.current_version[:etag]}", :red]
+                logs << ["      removed: #{cache_debug.removed_segments}", :red]
+                logs << ["        added: #{cache_debug.added_segments}", :red]
+              elsif cache_debug.new_key?
+                logs << [" [+] cache key added #{cache_debug.current_version[:etag]}", :red, true]
+              else
+                logs << [" [✓] #{cache_debug.current_version[:etag]}", :green, true]
+              end
+            end
           else
-            ["Rendering:", :green, true]
+            logs << ["Rendering:", :green, true]
           end
           logs << ["Took: #{took}ms", :magenta, true]
         end

lib/graphiti/util/cache_debug.rb

@@ -0,0 +1,91 @@
+module Graphiti
+  module Util
+    class CacheDebug
+      attr_reader :proxy
+
+      def initialize(proxy)
+        @proxy = proxy
+      end
+
+      def last_version
+        @last_version ||= Graphiti.cache.read(key) || {}
+      end
+
+      def name
+        "#{Graphiti.context[:object].request.method} #{Graphiti.context[:object].request.url}"
+      end
+
+      def key
+        "graphiti:debug/#{name}"
+      end
+
+      def current_version
+        @current_version ||= { 
+          cache_key: proxy.cache_key_with_version,
+          version: proxy.updated_at,
+          expires_in: proxy.cache_expires_in,
+          etag: proxy.etag,
+          miss_count: last_version[:miss_count].to_i + (changed_key? ? 1 : 0),
+          hit_count: last_version[:hit_count].to_i + (!changed_key? && !new_key? ? 1 : 0),
+          request_count: last_version[:request_count].to_i + (last_version.present? ? 1 : 0)
+        }
+      end
+
+      def analyze
+        yield self
+        save
+      end
+
+      def request_count
+        current_version[:request_count]
+      end
+
+      def miss_count
+        current_version[:miss_count]
+      end
+
+      def hit_count
+        current_version[:hit_count]
+      end
+
+      def change_percentage
+        return 0 if request_count == 0
+
+        (miss_count.to_i / request_count.to_f * 100).round(1)
+      rescue Exception => e
+        puts e.inspect
+      end
+
+      def volatile?
+        change_percentage > 50
+      end
+
+      def new_key?
+        last_version[:cache_key].blank? && proxy.cache_key_with_version
+      end
+
+      def changed_key?
+        last_version[:cache_key] != proxy.cache_key_with_version && !new_key?
+      end
+
+      def removed_segments
+        changes[1] - changes[0]
+      end
+
+      def added_segments
+        changes[0] - changes[1]
+      end
+
+      def changes
+        sub_keys_old = last_version[:cache_key]&.scan(/\w+\/query-[a-z0-9-]+\/args-[a-z0-9-]+/).to_a || []
+        sub_keys_new = current_version[:cache_key]&.scan(/\w+\/query-[a-z0-9-]+\/args-[a-z0-9-]+/).to_a || []
+
+        [sub_keys_old, sub_keys_new]
+      end
+
+      def save
+        Graphiti.cache.write(key, current_version)
+      end
+    end
+  end
+end