Better mem-leak prevention in expirable set

lib/sidekiq/throttled/expirable_set.rb

@@ -31,7 +31,14 @@ def initialize(ttl)
       # @param element [Object]
       # @return [ExpirableSet] self
       def add(element)
+        # cleanup expired elements to avoid mem-leak
+        horizon = now
+        expired = @elements.each_pair.select { |(_, sunset)| expired?(sunset, horizon) }
+        expired.each { |pair| @elements.delete_pair(*pair) }
+
+        # add new element
         @elements[element] = now + @ttl
+
         self
       end
 
@@ -40,16 +47,11 @@ def each
         return to_enum __method__ unless block_given?
 
         horizon = now
-        expired = []
 
         @elements.each_pair do |element, sunset|
-          next yield element if horizon < sunset
-
-          expired << [element, sunset]
+          yield element unless expired?(sunset, horizon)
         end
 
-        expired.each { |pair| @elements.delete_pair(*pair) }
-
         self
       end
 
@@ -59,6 +61,10 @@ def each
       def now
         ::Process.clock_gettime(::Process::CLOCK_MONOTONIC)
       end
+
+      def expired?(sunset, horizon)
+        sunset <= horizon
+      end
     end
   end
 end