/// <summary>
/// Returns the first document of a cursor returned by a cursor source.
/// </summary>
/// <typeparam name="TDocument">The type of the document.</typeparam>
/// <param name="source">The source.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>The first document.</returns>
public static TDocument First <TDocument>(this IAsyncCursorSource <TDocument> source, CancellationToken cancellationToken = default(CancellationToken))
{
using (var cursor = source.ToCursor(cancellationToken))
{
return(cursor.First(cancellationToken));
}
}
private void GetCache(bool reset)
{
lock (_lock)
{
if (_cursor == null || reset)
{
_cursor = _finder.ToCursor();
_elementCache = _cursor.MoveNext() ? _cursor.Current.ToList() : new List <BsonDocument>();
}
if (_elementCache != null && _position >= _elementCache.Count())
{
_elementCache?.Clear();
_elementCache = _cursor.MoveNext() ? _cursor.Current.ToList() : new List <BsonDocument>();
_passedElements += _position;
_position = 0;
}
}
}
// public methods
public IEnumerator <TDocument> GetEnumerator()
{
var cursor = _source.ToCursor(_cancellationToken);
return(new AsyncCursorEnumerator <TDocument>(cursor, _cancellationToken));
}