feat: Add support for caching renders in Graphiti, and better support…

… using etags and stale? in the controller (#424)

-  add `cache_key` method to resource instance, which generates a combined stable cache key based on resource identifiers, the specified sideloads, and any specified extra_fields or fields, pages, or links which will affect the response.

- add `cache_key_with_version` method to resource instance, which is the same as above with the last updated_at added in

- add `updated_at` method to resource instance, which returns the max `updated_at` date of the resource and any specified sideloads

- add `etag` method to resource instance,  which generates a Weak Etag based on the `cache_key_with_version` response. With `etag` and `updated_at` methods on a resource instance, using `stale?(@resource)` will work out of the box.

- allow `cache_resource` directive combined when `Graphiti.config.cache_rendering=true` and `Graphiti.cache = ::Rails.cache` to execute rendering logic in Graphiti wrapped in a cache block using the keys above, often times dramatically improving response time.

lib/graphiti.rb

@@ -106,6 +106,14 @@ def self.setup!
       r.apply_sideloads_to_serializer
     end
   end
+
+  def self.cache=(val)
+    @cache = val
+  end
+
+  def self.cache
+    @cache
+  end
 end
 
 require "graphiti/version"
@@ -177,6 +185,7 @@ def self.setup!
 require "graphiti/serializer"
 require "graphiti/query"
 require "graphiti/debugger"
+require "graphiti/util/cache_debug"
 
 if defined?(ActiveRecord)
   require "graphiti/adapters/active_record"

lib/graphiti/configuration.rb

@@ -20,6 +20,7 @@ class Configuration
     attr_reader :debug, :debug_models
 
     attr_writer :schema_path
+    attr_writer :cache_rendering
 
     # Set defaults
     # @api private
@@ -32,6 +33,7 @@ def initialize
       @pagination_links = false
       @typecast_reads = true
       @raise_on_missing_sidepost = true
+      @cache_rendering = false
       self.debug = ENV.fetch("GRAPHITI_DEBUG", true)
       self.debug_models = ENV.fetch("GRAPHITI_DEBUG_MODELS", false)
 
@@ -52,6 +54,16 @@ def initialize
       end
     end
 
+    def cache_rendering?
+      use_caching = @cache_rendering && Graphiti.cache.respond_to?(:fetch)
+
+      use_caching.tap do |use|
+        if @cache_rendering && !Graphiti.cache&.respond_to?(:fetch)
+          raise "You must configure a cache store in order to use cache_rendering. Set Graphiti.cache = Rails.cache, for example."
+        end
+      end
+    end
+
     def schema_path
       @schema_path ||= raise("No schema_path defined! Set Graphiti.config.schema_path to save your schema.")
     end

lib/graphiti/debugger.rb

@@ -98,7 +98,30 @@ def on_render(name, start, stop, id, payload)
           took = ((stop - start) * 1000.0).round(2)
           logs << [""]
           logs << ["=== Graphiti Debug", :green, true]
-          logs << ["Rendering:", :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]
+              logs << if cache_debug.volatile?
+                [" \\_ volatile | Request count: #{cache_debug.request_count} | Hit count: #{cache_debug.hit_count}", :red, true]
+              else
+                [" \\_   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
+            logs << ["Rendering:", :green, true]
+          end
           logs << ["Took: #{took}ms", :magenta, true]
         end
       end

lib/graphiti/query.rb

@@ -1,3 +1,5 @@
+require "digest"
+
 module Graphiti
   class Query
     attr_reader :resource, :association_name, :params, :action
@@ -232,8 +234,22 @@ def paginate?
       ![false, "false"].include?(@params[:paginate])
     end
 
+    def cache_key
+      "args-#{query_cache_key}"
+    end
+
     private
 
+    def query_cache_key
+      attrs = {extra_fields: extra_fields,
+               fields: fields,
+               links: links?,
+               pagination_links: pagination_links?,
+               format: params[:format]}
+
+      Digest::SHA1.hexdigest(attrs.to_s)
+    end
+
     def cast_page_param(name, value)
       if [:before, :after].include?(name)
         decode_cursor(value)

lib/graphiti/renderer.rb

@@ -68,7 +68,14 @@ def render(renderer)
         options[:meta][:debug] = Debugger.to_a if debug_json?
         options[:proxy] = proxy
 
-        renderer.render(records, options)
+        if proxy.cache? && Graphiti.config.cache_rendering?
+          Graphiti.cache.fetch("graphiti:render/#{proxy.cache_key}", version: proxy.updated_at, expires_in: proxy.cache_expires_in) do
+            options.delete(:cache) # ensure that we don't use JSONAPI-Resources's built-in caching logic
+            renderer.render(records, options)
+          end
+        else
+          renderer.render(records, options)
+        end
       end
     end
 

lib/graphiti/resource/interface.rb

@@ -4,6 +4,11 @@ module Interface
       extend ActiveSupport::Concern
 
       class_methods do
+        def cache_resource(expires_in: false)
+          @cache_resource = true
+          @cache_expires_in = expires_in
+        end
+
         def all(params = {}, base_scope = nil)
           validate_request!(params)
           _all(params, {}, base_scope)
@@ -13,7 +18,7 @@ def all(params = {}, base_scope = nil)
         def _all(params, opts, base_scope)
           runner = Runner.new(self, params, opts.delete(:query), :all)
           opts[:params] = params
-          runner.proxy(base_scope, opts)
+          runner.proxy(base_scope, opts.merge(caching_options))
         end
 
         def find(params = {}, base_scope = nil)
@@ -31,10 +36,14 @@ def _find(params = {}, base_scope = nil)
           params[:filter][:id] = id if id
 
           runner = Runner.new(self, params, nil, :find)
-          runner.proxy base_scope,
+
+          find_options = {
             single: true,
             raise_on_missing: true,
             bypass_required_filters: true
+          }.merge(caching_options)
+
+          runner.proxy base_scope, find_options
         end
 
         def build(params, base_scope = nil)
@@ -45,6 +54,10 @@ def build(params, base_scope = nil)
 
         private
 
+        def caching_options
+          {cache: @cache_resource, cache_expires_in: @cache_expires_in}
+        end
+
         def validate_request!(params)
           return if Graphiti.context[:graphql] || !validate_endpoints?
 

lib/graphiti/resource_proxy.rb

@@ -2,20 +2,31 @@ module Graphiti
   class ResourceProxy
     include Enumerable
 
-    attr_reader :resource, :query, :scope, :payload
+    attr_reader :resource, :query, :scope, :payload, :cache_expires_in, :cache
 
     def initialize(resource, scope, query,
       payload: nil,
       single: false,
-      raise_on_missing: false)
+      raise_on_missing: false,
+      cache: nil,
+      cache_expires_in: nil)
+
       @resource = resource
       @scope = scope
       @query = query
       @payload = payload
       @single = single
       @raise_on_missing = raise_on_missing
+      @cache = cache
+      @cache_expires_in = cache_expires_in
+    end
+
+    def cache?
+      !!@cache
     end
 
+    alias_method :cached?, :cache?
+
     def single?
       !!@single
     end
@@ -180,6 +191,22 @@ def debug_requested?
       query.debug_requested?
     end
 
+    def updated_at
+      @scope.updated_at
+    end
+
+    def etag
+      "W/#{ActiveSupport::Digest.hexdigest(cache_key_with_version.to_s)}"
+    end
+
+    def cache_key
+      ActiveSupport::Cache.expand_cache_key([@scope.cache_key, @query.cache_key])
+    end
+
+    def cache_key_with_version
+      ActiveSupport::Cache.expand_cache_key([@scope.cache_key_with_version, @query.cache_key])
+    end
+
     private
 
     def persist

lib/graphiti/runner.rb

@@ -71,7 +71,9 @@ def proxy(base = nil, opts = {})
         query,
         payload: deserialized_payload,
         single: opts[:single],
-        raise_on_missing: opts[:raise_on_missing]
+        raise_on_missing: opts[:raise_on_missing],
+        cache: opts[:cache],
+        cache_expires_in: opts[:cache_expires_in]
     end
   end
 end

lib/graphiti/scope.rb

@@ -67,8 +67,64 @@ def resolve_sideloads(results)
       end
     end
 
+    def parent_resource
+      @resource
+    end
+
+    def cache_key
+      # This is the combined cache key for the base query and the query for all sideloads
+      # Changing the query will yield a different cache key
+
+      cache_keys = sideload_resource_proxies.map { |proxy| proxy.try(:cache_key) }
+
+      cache_keys << @object.try(:cache_key) # this is what calls into the ORM (ActiveRecord, most likely)
+      ActiveSupport::Cache.expand_cache_key(cache_keys.flatten.compact)
+    end
+
+    def cache_key_with_version
+      # This is the combined and versioned cache key for the base query and the query for all sideloads
+      # If any returned model's updated_at changes, this key will change
+
+      cache_keys = sideload_resource_proxies.map { |proxy| proxy.try(:cache_key_with_version) }
+
+      cache_keys << @object.try(:cache_key_with_version) # this is what calls into ORM (ActiveRecord, most likely)
+      ActiveSupport::Cache.expand_cache_key(cache_keys.flatten.compact)
+    end
+
+    def updated_at
+      updated_ats = sideload_resource_proxies.map(&:updated_at)
+
+      begin
+        updated_ats << @object.maximum(:updated_at)
+      rescue => e
+        Graphiti.log("error calculating last_modified_at for #{@resource.class}")
+        Graphiti.log(e)
+      end
+
+      updated_ats.compact.max
+    end
+    alias_method :last_modified_at, :updated_at
+
     private
 
+    def sideload_resource_proxies
+      @sideload_resource_proxies ||= begin
+        @object = @resource.before_resolve(@object, @query)
+        results = @resource.resolve(@object)
+
+        [].tap do |proxies|
+          unless @query.sideloads.empty?
+            @query.sideloads.each_pair do |name, q|
+              sideload = @resource.class.sideload(name)
+              next if sideload.nil? || sideload.shared_remote?
+
+              proxies << sideload.build_resource_proxy(results, q, parent_resource)
+            end
+          end
+        end.flatten
+      end
+    end
+
     def broadcast_data
       opts = {
         resource: @resource,

lib/graphiti/serializer.rb

@@ -99,7 +99,7 @@ def strip_relationships!(hash)
 
     def strip_relationships?
       return false unless Graphiti.config.links_on_demand
-      params = Graphiti.context[:object].params || {}
+      params = Graphiti.context[:object]&.params || {}
       [false, nil, "false"].include?(params[:links])
     end
   end

lib/graphiti/sideload.rb

@@ -209,13 +209,16 @@ def base_scope
       end
     end
 
-    def load(parents, query, graph_parent)
-      params, opts, proxy = nil, nil, nil
+    def build_resource_proxy(parents, query, graph_parent)
+      params = nil
+      opts = nil
+      proxy = nil
 
       with_error_handling Errors::SideloadParamsError do
         params = load_params(parents, query)
         params_proc&.call(params, parents, context)
         return [] if blank_query?(params)
+
         opts = load_options(parents, query)
         opts[:sideload] = self
         opts[:parent] = graph_parent
@@ -228,7 +231,11 @@ def load(parents, query, graph_parent)
         pre_load_proc&.call(proxy, parents)
       end
 
-      proxy.to_a
+      proxy
+    end
+
+    def load(parents, query, graph_parent)
+      build_resource_proxy(parents, query, graph_parent).to_a
     end
 
     # Override in subclass