public IEnumerator <TDocument> Execute(IConnectionProvider connectionProvider)
{
MongoReplyMessage <TDocument> reply = null;
try
{
var count = 0;
var limit = (_limit >= 0) ? _limit : -_limit;
reply = GetFirstBatch(connectionProvider);
foreach (var document in reply.Documents)
{
if (limit != 0 && count == limit)
{
yield break;
}
yield return(document);
count++;
}
while (reply.CursorId != 0)
{
reply = GetNextBatch(connectionProvider, reply.CursorId);
foreach (var document in reply.Documents)
{
if (limit != 0 && count == limit)
{
yield break;
}
yield return(document);
count++;
}
if (reply.CursorId != 0 && (_flags & QueryFlags.TailableCursor) != 0)
{
if ((reply.ResponseFlags & ResponseFlags.AwaitCapable) == 0)
{
Thread.Sleep(TimeSpan.FromMilliseconds(100));
}
}
}
}
finally
{
if (reply != null && reply.CursorId != 0)
{
try
{
KillCursor(connectionProvider, reply.CursorId);
}
catch
{
// don't throw any exceptions from the finally block
}
}
}
}
/// <summary>
/// Moves to the next result and returns true if another result is available.
/// </summary>
/// <returns>True if another result is available.</returns>
public bool MoveNext()
{
if (disposed)
{
throw new ObjectDisposedException("MongoCursorEnumerator");
}
if (done)
{
// normally once MoveNext returns false the enumerator is done and MoveNext will return false forever after that
// but for a tailable cursor MoveNext can return false for awhile and eventually return true again once new data arrives
// so a tailable cursor is never really done (at least while there is still an open cursor)
if ((cursor.Flags & QueryFlags.TailableCursor) != 0 && openCursorId != 0)
{
done = false;
}
else
{
return(false);
}
}
if (!started)
{
reply = GetFirst();
if (reply.Documents.Count == 0)
{
reply = null;
done = true;
return(false);
}
replyIndex = -1;
started = true;
}
if (positiveLimit != 0 && count == positiveLimit)
{
KillCursor(); // early exit
reply = null;
done = true;
return(false);
}
// reply would only be null if the cursor is tailable and temporarily ran out of documents
if (reply != null && replyIndex < reply.Documents.Count - 1)
{
replyIndex++; // move to next document in the current reply
}
else
{
if (openCursorId != 0)
{
reply = GetMore();
if (reply.Documents.Count == 0)
{
reply = null;
done = true;
return(false);
}
replyIndex = 0;
}
else
{
reply = null;
done = true;
return(false);
}
}
count++;
return(true);
}
