Microsoft.AspNet.SignalR.Messaging.ScaleoutStore.GetMessages C# (CSharp) Method

        public MessageStoreResult<ScaleoutMapping> GetMessages(ulong firstMessageIdRequestedByClient)
        {
            ulong nextFreeMessageId = (ulong)Volatile.Read(ref _nextFreeMessageId);

            // Case 1:
            // The client is already up-to-date with the message store, so we return no data.
            if (nextFreeMessageId <= firstMessageIdRequestedByClient)
            {
                return new MessageStoreResult<ScaleoutMapping>(firstMessageIdRequestedByClient, _emptyArraySegment, hasMoreData: false);
            }

            // look for the fragment containing the start of the data requested by the client
            ulong fragmentNum;
            int idxIntoFragmentsArray, idxIntoFragment;
            GetFragmentOffsets(firstMessageIdRequestedByClient, out fragmentNum, out idxIntoFragmentsArray, out idxIntoFragment);
            Fragment thisFragment = _fragments[idxIntoFragmentsArray];
            ulong firstMessageIdInThisFragment = GetMessageId(thisFragment.FragmentNum, offset: 0);
            ulong firstMessageIdInNextFragment = firstMessageIdInThisFragment + _fragmentSize;

            // Case 2:
            // This fragment contains the first part of the data the client requested.
            if (firstMessageIdInThisFragment <= firstMessageIdRequestedByClient && firstMessageIdRequestedByClient < firstMessageIdInNextFragment)
            {
                int count = (int)(Math.Min(nextFreeMessageId, firstMessageIdInNextFragment) - firstMessageIdRequestedByClient);

                var retMessages = new ArraySegment<ScaleoutMapping>(thisFragment.Data, idxIntoFragment, count);

                return new MessageStoreResult<ScaleoutMapping>(firstMessageIdRequestedByClient, retMessages, hasMoreData: (nextFreeMessageId > firstMessageIdInNextFragment));
            }

            // Case 3:
            // The client has missed messages, so we need to send him the earliest fragment we have.
            while (true)
            {
                GetFragmentOffsets(nextFreeMessageId, out fragmentNum, out idxIntoFragmentsArray, out idxIntoFragment);
                Fragment tailFragment = _fragments[(idxIntoFragmentsArray + 1) % _fragments.Length];
                if (tailFragment.FragmentNum < fragmentNum)
                {
                    firstMessageIdInThisFragment = GetMessageId(tailFragment.FragmentNum, offset: 0);

                    return new MessageStoreResult<ScaleoutMapping>(firstMessageIdInThisFragment, new ArraySegment<ScaleoutMapping>(tailFragment.Data, 0, tailFragment.Length), hasMoreData: true);
                }
                nextFreeMessageId = (ulong)Volatile.Read(ref _nextFreeMessageId);
            }
        }