RazorDB.KeyValueStore.InternalGet C# (CSharp) Method

        private Value InternalGet(Key lookupKey) {
            Value output = Value.Empty;
            // Capture copy of the rotated table if there is one
            var rotatedMemTable = _rotatedJournaledMemTable;

            // somtimes on shutdown this is null
            if (_currentJournaledMemTable == null || _manifest == null)
                return Value.Empty;
                
            // First check the current memtable
            if (_currentJournaledMemTable.Lookup(lookupKey, out output)) {
                return output;
            }

            // Check the table in rotation
            if (rotatedMemTable != null) {
                if (rotatedMemTable.Lookup(lookupKey, out output)) {
                    return output;
                }
            }


            // Now check the files on disk
            using (var manifest = _manifest.GetLatestManifest()) {
                // Must check all pages on level 0
                var zeroPages = manifest.GetPagesAtLevel(0).OrderByDescending((page) => page.Version);
                foreach (var page in zeroPages) {
                    if (SortedBlockTable.Lookup(_manifest.BaseFileName, page.Level, page.Version, _cache, lookupKey, out output, _exceptionHandling, _manifest.Logger)) {
                        return output;
                    }
                }
                // If not found, must check pages on the higher levels, but we can use the page index to make the search quicker
                for (int level = 1; level < manifest.NumLevels; level++) {
                    var page = manifest.FindPageForKey(level, lookupKey);
                    if (page != null && SortedBlockTable.Lookup(_manifest.BaseFileName, page.Level, page.Version, _cache, lookupKey, out output, _exceptionHandling, _manifest.Logger)) {
                        return output;
                    }
                }
            }
            // OK, not found anywhere, return null
            return Value.Empty;
        }