Cache URLFilter results of string inputs per site

lib/jekyll/filters/url_filters.rb

@@ -9,8 +9,18 @@ module URLFilters
       #
       # Returns the absolute URL as a String.
       def absolute_url(input)
-        cache = (@context.registers[:cached_absolute_urls] ||= {})
+        return if input.nil?
+
+        cache = if input.is_a?(String)
+                  (@context.registers[:site].filter_cache[:absolute_url] ||= {})
+                else
+                  (@context.registers[:cached_absolute_url] ||= {})
+                end
         cache[input] ||= compute_absolute_url(input)
+
+        # Duplicate cached string so that the cached value is never mutated by
+        # a subsequent filter.
+        cache[input].dup
       end
 
       # Produces a URL relative to the domain root based on site.baseurl
@@ -20,8 +30,18 @@ def absolute_url(input)
       #
       # Returns a URL relative to the domain root as a String.
       def relative_url(input)
-        cache = (@context.registers[:cached_relative_urls] ||= {})
+        return if input.nil?
+
+        cache = if input.is_a?(String)
+                  (@context.registers[:site].filter_cache[:relative_url] ||= {})
+                else
+                  (@context.registers[:cached_relative_url] ||= {})
+                end
         cache[input] ||= compute_relative_url(input)
+
+        # Duplicate cached string so that the cached value is never mutated by
+        # a subsequent filter.
+        cache[input].dup
       end
 
       # Strips trailing `/index.html` from URLs to create pretty permalinks
@@ -38,8 +58,6 @@ def strip_index(input)
       private
 
       def compute_absolute_url(input)
-        return if input.nil?
-
         input = input.url if input.respond_to?(:url)
         return input if Addressable::URI.parse(input.to_s).absolute?
 
@@ -53,8 +71,6 @@ def compute_absolute_url(input)
       end
 
       def compute_relative_url(input)
-        return if input.nil?
-
         input = input.url if input.respond_to?(:url)
         return input if Addressable::URI.parse(input.to_s).absolute?
 

lib/jekyll/site.rb

@@ -10,7 +10,7 @@ class Site
                   :gems, :plugin_manager, :theme
 
     attr_accessor :converters, :generators, :reader
-    attr_reader   :regenerator, :liquid_renderer, :includes_load_paths
+    attr_reader   :regenerator, :liquid_renderer, :includes_load_paths, :filter_cache
 
     # Public: Initialize a new Site.
     #
@@ -23,6 +23,7 @@ def initialize(config)
       self.config = config
 
       @cache_dir       = in_source_dir(config["cache_dir"])
+      @filter_cache    = {}
 
       @reader          = Reader.new(self)
       @regenerator     = Regenerator.new(self)

test/test_filters.rb

@@ -596,6 +596,7 @@ def select; end
         assert_equal "/front_matter.erb", page.url
         url = filter.relative_url(page.url)
         url << "foo"
+        assert_equal "/front_matter.erb", filter.relative_url(page.url)
         assert_equal "/front_matter.erb", page.url
       end