Ractors

End a serializer definition with make_shareable! to serialize in other Ractors. Define serializers in the main Ractor, then serialize anywhere:

class UserSerializer < Serega
  attribute :name
  make_shareable!
end

Ractor.new(user) { |user| UserSerializer.to_h(user) }.value
# => {name: "Ann"}

• Call make_shareable! in relation serializers too. Nested serializers defined with a block become shareable with their parent.

• A shareable serializer can not be changed.

• Each Ractor builds and caches its own serialization plans and presenter class.

• On a Ruby without Ractors, for example TruffleRuby, make_shareable! only locks the serializer.

What can be shared

make_shareable! deep-freezes the serializer definitions with Ractor.make_shareable: attribute options, formatters, batch loaders, preload_with and prepare_initial_objects handlers.

• A block given to attribute, batch, formatter or another definition is shareable when it is written in the serializer class and refers only to shareable values.

• A callable object that changes its own state, for example a formatter that caches values in an instance variable, raises FrozenError when it serializes.

A serializer with a definition that can not be shared serializes in the main Ractor only. In other Ractors it raises Serega::SeregaError with the reason:

class UserSerializer < Serega
  suffix = +"!"
  attribute :greeting, value: proc { |user| user.name + suffix }
  make_shareable!
end

UserSerializer.to_h(user) # => {greeting: "Ann!"}

Ractor.new(user) { |user| UserSerializer.to_h(user) }.value
# => Serega::SeregaError: Attribute :greeting of UserSerializer can not be
#    shared between Ractors (app/serializers/user_serializer.rb:3): cannot make
#    a shareable Proc because it can refer unshareable object "!" from variable
#    'suffix'