Using write with unless_exist + expires_in should unlock after the given...

Using write with unless_exist + expires_in should unlock after the given expires_in and not 5 minutes later (#40260)
Co-authored-by: NJye Lee <jyelee124@gmail.com>
Co-authored-by: NEugene Kenny <elkenny@gmail.com>

activesupport/CHANGELOG.md

+*   Fix bug to make memcached write_entry expire correctly with unless_exist
+
+    *Jye Lee*
+
 *   Add `ActiveSupport::Duration` conversion methods
 
     `in_seconds`, `in_minutes`, `in_hours`, `in_days`, `in_weeks`, `in_months`, and `in_years` return the respective duration covered.

activesupport/lib/active_support/cache/mem_cache_store.rb

@@ -144,7 +144,7 @@ def write_entry(key, entry, **options)
           method = options[:unless_exist] ? :add : :set
           value = options[:raw] ? entry.value.to_s : entry
           expires_in = options[:expires_in].to_i
-          if expires_in > 0 && !options[:raw]
+          if options[:race_condition_ttl] && expires_in > 0 && !options[:raw]
             # Set the memcache expire a few minutes in the future to support race condition ttls on read
             expires_in += 5.minutes
           end

activesupport/test/cache/stores/mem_cache_store_test.rb

@@ -161,6 +161,13 @@ def test_no_multiple_compress
     end
   end
 
+  def test_unless_exist_expires_when_configured
+    cache = ActiveSupport::Cache.lookup_store(:mem_cache_store)
+    assert_called_with cache.instance_variable_get(:@data), :add, [ "foo", ActiveSupport::Cache::Entry, 1, Hash ] do
+      cache.write("foo", "bar", expires_in: 1, unless_exist: true)
+    end
+  end
+
   private
     def random_string(length)
       (0...length).map { (65 + rand(26)).chr }.join