/// <summary>
/// Searches the cache for an entity with the specified key using the optional
/// entity retriever delegate to fetch or construct the entity if it is not present
/// in the cache. This override accepts a specific entity lifespan.
/// </summary>
/// <param name="key">The key used to identify the entity in the cache.</param>
/// <param name="retriever">The entity retriever delegate or <c>null</c>.</param>
/// <param name="lifespan">The maximum duration that a retreive entities should remain in the cache.</param>
/// <returns>The cached or retreived entity or <c>null</c> if it could not be found or retrieved.</returns>
/// <exception cref="ArgumentNullException">Thrown if <paramref name="key" /> is <c>null</c>.</exception>
public TEntity Get(TKey key, PersistedEntityRetriever <TEntity> retriever, TimeSpan lifespan)
{
TEntity entity;
entity = Get(key);
if (entity != null)
{
return(entity);
}
if (retriever == null)
{
return(null);
}
entity = retriever();
if (entity == null)
{
return(null);
}
Add(key, entity, lifespan);
return(entity);
}
/// <summary>
/// Searches the cache for an entity with the specified key using the optional
/// entity retriever delegate to fetch or construct the entity if it is not present
/// in the cache. This override uses the default entity lifespan.
/// </summary>
/// <param name="key">The key used to identify the entity in the cache.</param>
/// <param name="retriever">The entity retriever delegate or <c>null</c>.</param>
/// <returns>The cached or retreived entity or <c>null</c> if it could not be found or retrieved.</returns>
/// <exception cref="ArgumentNullException">Thrown if <paramref name="key" /> is <c>null</c>.</exception>
public TEntity Get(TKey key, PersistedEntityRetriever <TEntity> retriever)
{
return(Get(key, retriever, defTTL));
}
