SingletonCache

SingletonCache enables mapping every key to a single instance of a value, and keeping the value alive only while it is in use. This is useful when the total number of keys is large, but few will be in use at any moment and removing an item while in use would result in an invalid program state.

The example below shows how to implement exclusive Url access using a lock object per Url.

var urlLocks = new SingletonCache<Url, object>();

Url url = new Url("https://foo.com");

using (var lifetime = urlLocks.Acquire(url))
{
   lock (lifetime.Value)
   {
      // exclusive url access
   }
}