// load documents from document loader
protected IEnumerable <BsonDocument> LoadDocument(IEnumerable <IndexNode> nodes)
{
foreach (var node in nodes)
{
yield return(_lookup.Load(node));
// check if transaction all full of pages to clear before continue
_transaction.Safepoint();
}
}
public IEnumerator <BsonDocument> GetEnumerator()
{
// https://stackoverflow.com/a/34633464/3286260
// the index of the current item in the cache.
var index = 0;
#if DEBUG
if (_cache.Count > 0)
{
LOG($"document group cache request (key: {_key}, size: {_cache.Count})", "GROUPBY");
}
#endif
// enumerate the _cache first
for (; index < _cache.Count; index++)
{
var rawId = _cache[index];
yield return(_lookup.Load(rawId));
}
// continue enumeration of the original _enumerator, until it is finished.
// this adds items to the cache and increment
for (; _enumerator != null && _enumerator.MoveNext(); index++)
{
var current = _enumerator.Current;
ENSURE(current.RawId.IsEmpty == false, "rawId must have a valid value");
_cache.Add(current.RawId);
yield return(current);
}
if (_enumerator != null)
{
_enumerator.Dispose();
_enumerator = null;
}
// other users of the same instance of DocumentEnumerable
// can add more items to the cache, so we need to enumerate them as well
for (; index < _cache.Count; index++)
{
var rawId = _cache[index];
yield return(_lookup.Load(rawId));
}
}