IDisposable and Scoped values

Object pooling is a popular way to reduce memory allocations, using IDisposable wrappers to return objects to the pool. All cache classes in BitFaster.Caching own the lifetime of cached values, and will automatically dispose values when they are evicted. To safely store IDisposable pooled objects within the cache, use IScopedCache.

To avoid races using objects after they have been disposed by the cache, use IScopedCache which wraps values in Scoped<T>. The call to ScopedGetOrAdd creates a Lifetime that guarantees the scoped object will not be disposed until the lifetime is disposed. Scoped cache is thread safe, and guarantees correct disposal for concurrent lifetimes.

var lru = new ConcurrentLruBuilder<int, Disposable>()
    .WithCapacity(666)
    .AsScopedCache()
    .Build();
var valueFactory = new SomeDisposableValueFactory();

using (var lifetime = lru.ScopedGetOrAdd(1, valueFactory.Create))
{
    // lifetime.Value is guaranteed to be alive until the lifetime is disposed
}

class SomeDisposableValueFactory
{
   public Scoped<SomeDisposable>> Create(int key)
   {
      return new Scoped<SomeDisposable>(new SomeDisposable(key));
   }
}