/// <summary>
/// Expert: this method is called by <see cref="IndexReader"/>s which wrap other readers
/// (e.g. <see cref="CompositeReader"/> or <see cref="FilterAtomicReader"/>) to register the parent
/// at the child (this reader) on construction of the parent. When this reader is disposed,
/// it will mark all registered parents as disposed, too. The references to parent readers
/// are weak only, so they can be GCed once they are no longer in use.
/// @lucene.experimental
/// </summary>
public void RegisterParentReader(IndexReader reader)
{
EnsureOpen();
// LUCENENET specific - since ConditionalWeakTable doesn't synchronize
// on the enumerator, we need to do external synchronization to make them threadsafe.
UninterruptableMonitor.Enter(parentReadersLock);
try
{
#if FEATURE_CONDITIONALWEAKTABLE_ENUMERATOR
// LUCENENET: Since there is a set Add operation (unique) in Lucene, the equivalent
// operation in .NET is AddOrUpdate, which effectively does nothing if the key exists.
// Null is passed as a value, since it is not used anyway and .NET doesn't have a boolean
// reference type.
parentReaders.AddOrUpdate(key: reader, value: null);
#else
if (!parentReaders.TryGetValue(key: reader, out _))
{
parentReaders.Add(key: reader, value: null);
reader.SubscribeToGetParentReadersEvent(eventAggregator.GetEvent <Events.GetParentReadersEvent>());
}
#endif
}
finally
{
UninterruptableMonitor.Exit(parentReadersLock);
}
}
