Merge pull request rails#33932 from schneems/schneems/recyclable-key-support-cache

[close rails#33907] Error when using "recyclable" cache keys with a store that does not support it

Author: schneems

activerecord/lib/active_record/railtie.rb

@@ -88,6 +88,31 @@ class Railtie < Rails::Railtie # :nodoc:
       end
     end
 
+    initializer "Check for cache versioning support" do
+      config.after_initialize do |app|
+        ActiveSupport.on_load(:active_record) do
+          if app.config.active_record.cache_versioning && Rails.cache
+            unless Rails.cache.class.try(:supports_cache_versioning?)
+              raise <<-end_error
+
+You're using a cache store that doesn't support native cache versioning.
+Your best option is to upgrade to a newer version of #{Rails.cache.class}
+that supports cache versioning (#{Rails.cache.class}.supports_cache_versioning? #=> true).
+
+Next best, switch to a different cache store that does support cache versioning:
+https://guides.rubyonrails.org/caching_with_rails.html#cache-stores.
+
+To keep using the current cache store, you can turn off cache versioning entirely:
+
+    config.active_record.cache_versioning = false
+
+end_error
+            end
+          end
+        end
+      end
+    end
+
     initializer "active_record.check_schema_cache_dump" do
       if config.active_record.delete(:use_schema_cache_dump)
         config.after_initialize do |app|

activesupport/lib/active_support/cache/file_store.rb

@@ -26,6 +26,11 @@ def initialize(cache_path, options = nil)
         @cache_path = cache_path.to_s
       end
 
+      # Advertise cache versioning support.
+      def self.supports_cache_versioning?
+        true
+      end
+
       # Deletes all items from the cache. In this case it deletes all the entries in the specified
       # file store directory except for .keep or .gitkeep. Be careful which directory is specified in your
       # config file when using +FileStore+ because everything in that directory will be deleted.

activesupport/lib/active_support/cache/mem_cache_store.rb

@@ -47,6 +47,11 @@ def write_entry(key, entry, options)
           end
       end
 
+      # Advertise cache versioning support.
+      def self.supports_cache_versioning?
+        true
+      end
+
       prepend Strategy::LocalCache
       prepend LocalCacheWithRaw
 

activesupport/lib/active_support/cache/memory_store.rb

@@ -30,6 +30,11 @@ def initialize(options = nil)
         @pruning = false
       end
 
+      # Advertise cache versioning support.
+      def self.supports_cache_versioning?
+        true
+      end
+
       # Delete all data stored in a given cache store.
       def clear(options = nil)
         synchronize do

activesupport/lib/active_support/cache/null_store.rb

@@ -12,6 +12,11 @@ module Cache
     class NullStore < Store
       prepend Strategy::LocalCache
 
+      # Advertise cache versioning support.
+      def self.supports_cache_versioning?
+        true
+      end
+
       def clear(options = nil)
       end
 

activesupport/lib/active_support/cache/redis_cache_store.rb

@@ -66,6 +66,11 @@ class RedisCacheStore < Store
       SCAN_BATCH_SIZE = 1000
       private_constant :SCAN_BATCH_SIZE
 
+      # Advertise cache versioning support.
+      def self.supports_cache_versioning?
+        true
+      end
+
       # Support raw values in the local cache strategy.
       module LocalCacheWithRaw # :nodoc:
         private

railties/CHANGELOG.md

@@ -1,3 +1,10 @@
+*   Raise an error when "recyclable cache keys" are being used by a cache store
+    that does not explicitly support it. Custom cache keys that do support this feature
+    can bypass this error by implementing the `supports_cache_versioning?` method on their
+    class and returning a truthy value.
+
+    *Richard Schneeman*
+
 *   Support environment specific credentials file.
 
     For `production` environment look first for `config/credentials/production.yml.enc` file that can be decrypted by

railties/test/application/configuration_test.rb

@@ -124,6 +124,18 @@ class MyLogger < ::Logger
       assert_equal "MyLogger", Rails.application.config.logger.class.name
     end
 
+    test "raises an error if cache does not support recyclable cache keys" do
+      build_app(initializers: true)
+      add_to_env_config "production", "config.cache_store = Class.new {}.new"
+      add_to_env_config "production", "config.active_record.cache_versioning = true"
+
+      error = assert_raise(RuntimeError) do
+        app "production"
+      end
+
+      assert_match(/You're using a cache/, error.message)
+    end
+
     test "a renders exception on pending migration" do
       add_to_config <<-RUBY
         config.active_record.migration_error    = :page_load