Cache read-only objects

1 min

Most APIs in Optimizely CMS return read-only instances of objects, such as IContentLoader.Get<TContentData> which returns a read-only IContent instance.

To make changes to read-only instances, create a writable clone with the CreateWritableClone method, which has the following advantages:

Reduce memory consumption – Threads serving Web requests get the same instance of an object, effectively reducing the number of short-lived objects created.

Improve performance – Returning shared read-only instances offers better performance.

Cleaner architecture – This simplifies the implementation because you cannot change an instance of an object shared with other threads.

Classes that have the read-only support implements the IReadOnly<T> interface, which is defined as follows:

public interface IReadOnly {
  void MakeReadOnly();
  bool IsReadOnly {
    get;
  }
}

public interface IReadOnly<T>: IReadOnly {
  T CreateWritableClone();
}

The lifecycle of a typical IContent instance is as follows:

Create the IContent instance as mutable (which means writeable).

Populate the IContent instance with property values.

Call the IReadOnly.MakeReadOnly method to ensure that any contained objects are made read-only. The object is immutable for the remainder of its lifetime.

Add the object to the cache.