DBreeze.Scheme.GetTable C# (CSharp) Method

GetTable() private method

Returns table for READ, WRITE FUNC
private GetTable ( string userTableName ) : LTrie
userTableName string
return DBreeze.LianaTrie.LTrie
        internal LTrie GetTable(string userTableName)
        {
            string tableName = GetUserTableNameAsString(userTableName);

            //TODO pattern based mapping If table doesn't exist we create it with properties which could be supplied after db init as regex theme.

            //Schema protocol: 2 bytes - protocol version, other data
            //For protocol 1: first 8 bytes will be TheFileName, starting from db10000-dbN (0-N ulong). up to 10000 are reserved for dbreeze.

            //Table names are UTF-8 based, no limits

            ulong fileName = 0;
            OpenTable otl = null;

            _sync_openTablesHolder.EnterUpgradeableReadLock();
            try
            {

                _openTablesHolder.TryGetValue(tableName, out otl);

                if (otl != null)
                {
                    //Try to increase usage and return LTrie
                    otl.Add();
                    return otl.Trie;
                }

                //Probably table Exists in db but not in openTablesHolder

                _sync_openTablesHolder.EnterWriteLock();
                try
                {
                    //UpgradeableRead recheck
                    _openTablesHolder.TryGetValue(tableName, out otl);

                    if (otl != null)
                    {
                        //Try to increase usage and return LTrie
                        otl.Add();
                        return otl.Trie;
                    }

                    byte[] btTableName = GetUserTableNameAsByte(userTableName);

                    //Trying to get fileName from cache
                    fileName = this.cachedTableNames.GetFileName(tableName);
                    // LTrieRow row = null;
                    bool tableExists = false;

                    if (fileName == 0)
                    {
                        LTrieRow row = LTrie.GetKey(btTableName, false);

                        if (row.Exists)
                        {
                            tableExists = true;

                            byte[] fullValue = row.GetFullValue(false);
                            //Can be parsed different. First protocol version is 1
                            ushort schemeProtocol = fullValue.Substring(0, 2).To_UInt16_BigEndian();

                            switch (schemeProtocol)
                            {
                                case 1:
                                    fileName = fullValue.Substring(2, 8).To_UInt64_BigEndian();
                                    break;
                                default:
                                    throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.SCHEME_FILE_PROTOCOL_IS_UNKNOWN);
                            }
                        }
                        else
                        {
                            tableExists = false;
                            //Creating new table.

                            //Checking table name validity

                            //this will throw exception, if not valid
                            DbUserTables.UserTableNameIsOk(userTableName);

                            //Creating such table and renewing LastFileNumber counter

                            //Adding to LastFileNumber
                            LastFileNumber++;

                            ////Deleting physical files related to the table, if they existed - normally they should not
                            //DeleteAllReleatedTableFiles(Path.Combine(Engine.MainFolder, LastFileNumber.ToString()));

                            byte[] lft = LastFileNumber.To_8_bytes_array_BigEndian();

                            //Writing this number to Schema file
                            LTrie.Add(Encoding.UTF8.GetBytes(LastFileNumberKeyName), lft);

                            //Creating table self and writing to Schema file

                            LTrie.Add(btTableName,
                                new byte[] { 0, 1 }     //Protocol version 1
                                .Concat(lft));          //Number of the file

                            //Committing both records
                            LTrie.Commit();

                            fileName = LastFileNumber;

                            this.cachedTableNames.Add(tableName, fileName);
                        }
                    }
                    else
                        tableExists = true;

                    //Creating LTrie, adding it to _openTablesHolder

                    //Seeting up Trie TableName, OTHER SETTINGS

                    TrieSettings ts = new TrieSettings();
                    IStorage storage = null;

                    ////Checking if default Flusg Disk behaviour was overriden
                    //ts.DiskFlushBehaviour = Engine.Configuration.DiskFlushBehaviour;
                    ////Checking if we have alternative DiskFlush behaviour
                    //foreach (var pattern in Engine.Configuration.AlternativeDiskFlushBehaviour)
                    //{
                    //    //pattern.Key
                    //    if (DbUserTables.PatternsIntersect(pattern.Key, userTableName))
                    //    {

                    //        ts.DiskFlushBehaviour = pattern.Value;
                    //        break;
                    //    }
                    //}

                    string alternativeTableLocation = String.Empty;

                    if (CheckAlternativeTableLocationsIntersections(userTableName, out alternativeTableLocation))
                    {
                        ts.StorageWasOverriden = true;

                        if (alternativeTableLocation == String.Empty)
                        {
                            ts.AlternativeTableStorageType = DBreezeConfiguration.eStorage.MEMORY;

                            storage = new StorageLayer(Path.Combine(Engine.MainFolder, fileName.ToString()), ts, Engine.Configuration);
                        }
                        else
                        {
                            ts.AlternativeTableStorageType = DBreezeConfiguration.eStorage.DISK;
                            ts.AlternativeTableStorageFolder = alternativeTableLocation;

                            DirectoryInfo diAlt = new DirectoryInfo(alternativeTableLocation);
                            if (!diAlt.Exists)
                                diAlt.Create();

                            if (!tableExists)
                            {
                                //Deleting physical files related to the table, if they existed - normally they should not
                                DeleteAllReleatedTableFiles(Path.Combine(ts.AlternativeTableStorageFolder, LastFileNumber.ToString()));
                            }

                            storage = new StorageLayer(Path.Combine(ts.AlternativeTableStorageFolder, fileName.ToString()), ts, Engine.Configuration);
                        }
                    }
                    else
                    {
                        if (!tableExists)
                        {
                            //Deleting physical files related to the table, if they existed - normally they should not
                            DeleteAllReleatedTableFiles(Path.Combine(Engine.MainFolder, LastFileNumber.ToString()));
                        }

                        storage = new StorageLayer(Path.Combine(Engine.MainFolder, fileName.ToString()), ts, Engine.Configuration);
                    }

                    //storage = new StorageLayer(Path.Combine(Engine.MainFolder, fileName.ToString()), ts, Engine.Configuration);

                    LTrie trie = new LTrie(storage);

                    //Setting LTrie user table name
                    trie.TableName = userTableName;

                    //_openTablesHolder.Add(tableName, trie);

                    //Automatically increased usage in OpenTable constructor
                    _openTablesHolder.Add(tableName, new OpenTable(trie));

                    return trie;
                }
                catch (System.Exception ex)
                {
                    //CASCADE
                    throw ex;
                }
                finally
                {
                    _sync_openTablesHolder.ExitWriteLock();
                }
            }
            catch (Exception ex)
            {
                throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.SCHEME_GET_TABLE_WRITE_FAILED, tableName, ex);
            }
            finally
            {
                _sync_openTablesHolder.ExitUpgradeableReadLock();
            }
        }