Support idle_timeout in global compiler

lib/sass/compiler.rb

@@ -26,7 +26,7 @@ module Sass
   #   sass.close
   class Compiler
     def initialize
-      @dispatcher = ResilientDispatcher.new
+      @dispatcher = ResilientDispatcher.new(Dispatcher)
     end
 
     # Compiles the Sass file at +path+ to CSS.

lib/sass/compiler/resilient_dispatcher.rb

@@ -6,8 +6,9 @@ class Compiler
     #
     # It recovers from failures and continues to function.
     class ResilientDispatcher
-      def initialize
-        @dispatcher = Dispatcher.new
+      def initialize(dispatcher_class)
+        @dispatcher_class = dispatcher_class
+        @dispatcher = @dispatcher_class.new
         @mutex = Mutex.new
       end
 
@@ -29,7 +30,7 @@ def connect(...)
         @mutex.synchronize do
           @dispatcher.connect(...)
         rescue Errno::EBUSY
-          @dispatcher = Dispatcher.new
+          @dispatcher = @dispatcher_class.new
           @dispatcher.connect(...)
         end
       end

lib/sass/embedded.rb

@@ -54,10 +54,48 @@ def instance
       @mutex.synchronize do
         return @instance if @instance
 
-        @instance = Compiler.new
+        @instance = Class.new(Compiler) do
+          def initialize
+            @dispatcher = self.class.const_get(:ResilientDispatcher).new(Class.new(self.class.const_get(:Dispatcher)) do
+              def initialize
+                super
+
+                idle_timeout = 10
+                @last_accessed_time = current_time
+
+                Thread.new do
+                  duration = idle_timeout
+                  loop do
+                    sleep(duration.negative? ? idle_timeout : duration)
+                    evicted = @mutex.synchronize do
+                      duration = @last_accessed_time + idle_timeout - current_time
+                      @id = 0xffffffff if @observers.empty? && duration.negative?
+                    end
+                    break if evicted
+                  end
+                  close
+                end
+              end
+
+              def unsubscribe(id)
+                @last_accessed_time = current_time
+
+                super
+              end
+
+              private
+
+              def current_time
+                Process.clock_gettime(Process::CLOCK_MONOTONIC)
+              end
+            end)
+          end
+        end.new
+
         at_exit do
           @instance.close
         end
+
         @instance
       end
     end