EventStore.Core.Index.PTable.TryGetLargestEntry C# (CSharp) Method

        private bool TryGetLargestEntry(ulong stream, int startNumber, int endNumber, out IndexEntry entry)
        {
            Ensure.Nonnegative(startNumber, "startNumber");
            Ensure.Nonnegative(endNumber, "endNumber");

            entry = TableIndex.InvalidIndexEntry;

            var startKey = BuildKey(stream, startNumber);
            var endKey = BuildKey(stream, endNumber);

            if (startKey.GreaterThan(_maxEntry) || endKey.SmallerThan(_minEntry))
                return false;

            var workItem = GetWorkItem();
            try
            {
                var recordRange = LocateRecordRange(endKey);

                long low = recordRange.Lower;
                long high = recordRange.Upper;
                while (low < high)
                {
                    var mid = low + (high - low) / 2;
                    IndexEntry midpoint = ReadEntry(_indexEntrySize, mid, workItem, _version);
                    var midpointKey = new IndexEntryKey(midpoint.Stream, midpoint.Version);
                    if (midpointKey.GreaterThan(endKey))
                        low = mid + 1;
                    else
                        high = mid;
                }

                var candEntry = ReadEntry(_indexEntrySize, high, workItem, _version);
                var candKey = new IndexEntryKey(candEntry.Stream, candEntry.Version);
                if (candKey.GreaterThan(endKey))
                    throw new Exception(string.Format("candEntry ({0}@{1}) > startKey {2}, stream {3}, startNum {4}, endNum {5}, PTable: {6}.", candEntry.Stream, candEntry.Version, startKey, stream, startNumber, endNumber, Filename));
                if (candKey.SmallerThan(startKey))
                    return false;
                entry = candEntry;
                return true;
            }
            finally
            {
                ReturnWorkItem(workItem);
            }
        }