Refactor Jekyll::Cache (#7532)

Merge pull request 7532

features/cache.feature

@@ -26,3 +26,12 @@ Feature: Cache
     But the .jekyll-cache directory should not exist
     And the _site directory should exist
     And I should see "<p>Hello World</p>" in "_site/index.html"
+
+  Scenario: Disk usage in safe mode
+    Given I have an "index.md" page that contains "{{ site.title }}"
+    And I have a configuration file with "title" set to "Hello World"
+    When I run jekyll build --safe
+    Then I should get a zero exit status
+    But the .jekyll-cache directory should not exist
+    And the _site directory should exist
+    And I should see "<p>Hello World</p>" in "_site/index.html"

lib/jekyll/cache.rb

@@ -4,9 +4,59 @@ require "digest"
 
 module Jekyll
   class Cache
-    # rubocop:disable Style/ClassVars
-    @@caches = {}
-    @@disk_cache_enabled = true
+    # class-wide base cache
+    @base_cache = {}
+
+    # class-wide directive to write cache to disk is enabled by default
+    @disk_cache_enabled = true
+
+    class << self
+      # class-wide cache location
+      attr_accessor :cache_dir
+
+      # class-wide directive to write cache to disk
+      attr_reader :disk_cache_enabled
+
+      # class-wide base cache reader
+      attr_reader :base_cache
+
+      # Disable Marshaling cached items to disk
+      def disable_disk_cache!
+        @disk_cache_enabled = false
+      end
+
+      # Clear all caches
+      def clear
+        delete_cache_files
+        base_cache.each_value(&:clear)
+      end
+
+      # Compare the current config to the cached config
+      # If they are different, clear all caches
+      #
+      # Returns nothing.
+      def clear_if_config_changed(config)
+        config = config.inspect
+        cache = Jekyll::Cache.new "Jekyll::Cache"
+        return if cache.key?("config") && cache["config"] == config
+
+        clear
+        cache = Jekyll::Cache.new "Jekyll::Cache"
+        cache["config"] = config
+        nil
+      end
+
+      private
+
+      # Delete all cached items from all caches
+      #
+      # Returns nothing.
+      def delete_cache_files
+        FileUtils.rm_rf(@cache_dir) if disk_cache_enabled
+      end
+    end
+
+    #
 
     # Get an existing named cache, or create a new one if none exists
     #
@@ -14,27 +64,10 @@ module Jekyll
     #
     # Returns nothing.
     def initialize(name)
-      @cache = @@caches[name] ||= {}
+      @cache = Jekyll::Cache.base_cache[name] ||= {}
       @name = name.gsub(%r![^\w\s-]!, "-")
     end
 
-    # Set class-wide base_dir
-    def self.base_dir=(dir_path)
-      @@base_dir = dir_path
-    end
-
-    # Disable Marshaling cached items to disk
-    def self.disable_disk_cache!
-      @@disk_cache_enabled = false
-    end
-    # rubocop:enable Style/ClassVars
-
-    # Clear all caches
-    def self.clear
-      delete_cache_files
-      @@caches.each_value(&:clear)
-    end
-
     # Clear this particular cache
     def clear
       delete_cache_files
@@ -49,7 +82,7 @@ module Jekyll
       return @cache[key] if @cache.key?(key)
 
       path = path_to(hash(key))
-      if @@disk_cache_enabled && File.file?(path) && File.readable?(path)
+      if disk_cache_enabled? && File.file?(path) && File.readable?(path)
         @cache[key] = load(path)
       else
         raise
@@ -61,7 +94,7 @@ module Jekyll
     # Returns nothing.
     def []=(key, value)
       @cache[key] = value
-      return unless @@disk_cache_enabled
+      return unless disk_cache_enabled?
 
       path = path_to(hash(key))
       value = new Hash(value) if value.is_a?(Hash) && !value.default.nil?
@@ -70,9 +103,8 @@ module Jekyll
       Jekyll.logger.debug "Cache:", "Cannot dump object #{key}"
     end
 
-    # If an item already exists in the cache, retrieve it
-    # Else execute code block, and add the result to the cache, and return that
-    #   result
+    # If an item already exists in the cache, retrieve it.
+    # Else execute code block, and add the result to the cache, and return that result.
     def getset(key)
       self[key]
     rescue StandardError
@@ -86,10 +118,7 @@ module Jekyll
     # Returns nothing.
     def delete(key)
       @cache.delete(key)
-      return unless @@disk_cache_enabled
-
-      path = path_to(hash(key))
-      File.delete(path)
+      File.delete(path_to(hash(key))) if disk_cache_enabled?
     end
 
     # Check if `key` already exists in this cache
@@ -100,40 +129,27 @@ module Jekyll
       return true if @cache.key?(key)
       # Otherwise, it might be cached on disk
       # but we should not consider the disk cache if it is disabled
-      return false unless @@disk_cache_enabled
+      return false unless disk_cache_enabled?
 
       path = path_to(hash(key))
       File.file?(path) && File.readable?(path)
     end
 
-    # Compare the current config to the cached config
-    # If they are different, clear all caches
-    #
-    # Returns nothing.
-    def self.clear_if_config_changed(config)
-      config = config.inspect
-      cache = Jekyll::Cache.new "Jekyll::Cache"
-      return if cache.key?("config") && cache["config"] == config
-
-      clear
-      cache = Jekyll::Cache.new "Jekyll::Cache"
-      cache["config"] = config
-      nil
+    def disk_cache_enabled?
+      !!Jekyll::Cache.disk_cache_enabled
     end
 
     private
 
-    # Given a hashed key, return the path to where this item would be saved on
-    # disk
+    # Given a hashed key, return the path to where this item would be saved on disk.
     def path_to(hash = nil)
-      @base_dir ||= File.join(@@base_dir, @name)
+      @base_dir ||= File.join(Jekyll::Cache.cache_dir, @name)
       return @base_dir if hash.nil?
 
       File.join(@base_dir, hash[0..1], hash[2..-1]).freeze
     end
 
-    # Given a key, return a SHA2 hash that can be used for caching this item to
-    # disk
+    # Given a key, return a SHA2 hash that can be used for caching this item to disk.
     def hash(key)
       Digest::SHA2.hexdigest(key).freeze
     end
@@ -142,22 +158,14 @@ module Jekyll
     #
     # Returns nothing.
     def delete_cache_files
-      FileUtils.rm_rf(path_to) if @@disk_cache_enabled
+      FileUtils.rm_rf(path_to) if disk_cache_enabled?
     end
 
-    # Delete all cached items from all caches
-    #
-    # Returns nothing.
-    def self.delete_cache_files
-      FileUtils.rm_rf(@@base_dir) if @@disk_cache_enabled
-    end
-    private_class_method :delete_cache_files
-
-    # Load `path` from disk and return the result
+    # Load `path` from disk and return the result.
     # This MUST NEVER be called in Safe Mode
     # rubocop:disable Security/MarshalLoad
     def load(path)
-      raise unless @@disk_cache_enabled
+      raise unless disk_cache_enabled?
 
       cached_file = File.open(path, "rb")
       value = Marshal.load(cached_file)
@@ -166,15 +174,14 @@ module Jekyll
     end
     # rubocop:enable Security/MarshalLoad
 
-    # Given a path and a value, save value to disk at path
+    # Given a path and a value, save value to disk at path.
     # This should NEVER be called in Safe Mode
     #
     # Returns nothing.
     def dump(path, value)
-      return unless @@disk_cache_enabled
+      return unless disk_cache_enabled?
 
-      dir = File.dirname(path)
-      FileUtils.mkdir_p(dir)
+      FileUtils.mkdir_p(File.dirname(path))
       File.open(path, "wb") do |cached_file|
         Marshal.dump(value, cached_file)
       end

lib/jekyll/site.rb

@@ -469,7 +469,7 @@ module Jekyll
 
     # Disable Marshaling cache to disk in Safe Mode
     def configure_cache
-      Jekyll::Cache.base_dir = in_source_dir(config["cache_dir"], "Jekyll/Cache")
+      Jekyll::Cache.cache_dir = in_source_dir(config["cache_dir"], "Jekyll/Cache")
       Jekyll::Cache.disable_disk_cache! if safe
     end