/// <summary>
/// Gets a dynamic view of the underlying cache based on the parameters given.
/// </summary>
/// <param name="mode">View mode.</param>
/// <param name="startKey">Start key of view.</param>
/// <param name="endKey">End key of view.</param>
/// <param name="tailCount">Number of items to include in view.</param>
/// <param name="tailRange">Tail duration function. Takes last item's key and returns a new startKey.</param>
/// <returns>An instance of <see cref="ObservableKeyedView"/>.</returns>
/// <exception cref="ArgumentException"><paramref name="startKey"/> must be less than or equal to <paramref name="endKey"/>.</exception>
public ObservableKeyedView GetView(ObservableKeyedView.ViewMode mode, TKey startKey, TKey endKey, uint tailCount, Func <TKey, TKey> tailRange)
{
if (this.keyComparer.Compare(startKey, endKey) > 0)
{
throw new ArgumentException($"startKey ({startKey}) must be less than or equal to endKey ({endKey}).");
}
var viewKey = Tuple.Create(startKey, endKey, tailCount, tailRange);
WeakReference <ObservableKeyedView> weakView = null;
ObservableKeyedView view = null;
if (this.views.TryGetValue(viewKey, out weakView))
{
if (weakView.TryGetTarget(out view))
{
return(view);
}
else
{
view = new ObservableKeyedView(this, mode, startKey, endKey, tailCount, tailRange);
weakView.SetTarget(view);
}
}
else
{
view = new ObservableKeyedView(this, mode, startKey, endKey, tailCount, tailRange);
weakView = new WeakReference <ObservableKeyedView>(view);
this.views.Add(viewKey, weakView);
}
return(view);
}
/// <summary>
/// Gets a dynamic view of the underlying cache based on the parameters given.
/// </summary>
/// <param name="mode">View mode.</param>
/// <param name="startKey">Start key of view.</param>
/// <param name="endKey">End key of view.</param>
/// <param name="tailCount">Number of items to include in view.</param>
/// <param name="tailRange">Tail duration function. Takes last item's key and returns a new startKey.</param>
/// <returns>An instance of <see cref="ObservableKeyedView"/>.</returns>
/// <exception cref="ArgumentException"><paramref name="startKey"/> must be less than or equal to <paramref name="endKey"/>.</exception>
public ObservableKeyedView GetView(ObservableKeyedView.ViewMode mode, TKey startKey, TKey endKey, uint tailCount, Func <TKey, TKey> tailRange)
{
if (this.keyComparer.Compare(startKey, endKey) > 0)
{
throw new ArgumentException($"startKey ({startKey}) must be less than or equal to endKey ({endKey}).");
}
var viewKey = Tuple.Create(startKey, endKey, tailCount, tailRange);
WeakReference <ObservableKeyedView> weakView = null;
ObservableKeyedView view = null;
if (this.views.TryGetValue(viewKey, out weakView))
{
if (weakView.TryGetTarget(out view))
{
return(view);
}
else
{
view = new ObservableKeyedView(this, mode, startKey, endKey, tailCount, tailRange);
weakView.SetTarget(view);
// Sometimes the weak view gets deleted between when we grab it to check
// if it has a hard reference and when we actually set the new hard reference
// that we just created. If that happens, then the following code makes sure
// the weak view gets put back into the collection.
this.views[viewKey] = weakView;
}
}
else
{
view = new ObservableKeyedView(this, mode, startKey, endKey, tailCount, tailRange);
weakView = new WeakReference <ObservableKeyedView>(view);
this.views.Add(viewKey, weakView);
}
return(view);
}