Tortuga.Chain.PostgreSqlDataSource.ExecuteAsync C# (CSharp) Method

        protected override async Task<int?> ExecuteAsync(CommandExecutionToken<NpgsqlCommand, NpgsqlParameter> executionToken, CommandImplementationAsync<NpgsqlCommand> implementation, CancellationToken cancellationToken, object state)
        {
            if (executionToken == null)
                throw new ArgumentNullException("executionToken", "executionToken is null.");
            if (implementation == null)
                throw new ArgumentNullException("implementation", "implementation is null.");

            var startTime = DateTimeOffset.Now;
            OnExecutionStarted(executionToken, startTime, state);

            try
            {
                using (var con = await CreateConnectionAsync(cancellationToken).ConfigureAwait(false))
                {
                    using (var cmd = new NpgsqlCommand())
                    {
                        cmd.Connection = con;
                        if (DefaultCommandTimeout.HasValue)
                            cmd.CommandTimeout = (int)DefaultCommandTimeout.Value.TotalSeconds;
                        cmd.CommandText = executionToken.CommandText;
                        cmd.CommandType = executionToken.CommandType;
                        foreach (var param in executionToken.Parameters)
                            cmd.Parameters.Add(param);

                        executionToken.ApplyCommandOverrides(cmd);

                        int? rows;
                        if (((PostgreSqlCommandExecutionToken)executionToken).DereferenceCursors)
                            rows = await DereferenceCursorsAsync(cmd, implementation).ConfigureAwait(false);
                        else
                            rows = await implementation(cmd).ConfigureAwait(false);

                        executionToken.RaiseCommandExecuted(cmd, rows);
                        OnExecutionFinished(executionToken, startTime, DateTimeOffset.Now, rows, state);
                        return rows;
                    }
                }
            }
            catch (Exception ex)
            {
                if (cancellationToken.IsCancellationRequested) //convert Exception into a OperationCanceledException 
                {
                    var ex2 = new OperationCanceledException("Operation was canceled.", ex, cancellationToken);
                    OnExecutionCanceled(executionToken, startTime, DateTimeOffset.Now, state);
                    throw ex2;
                }
                else
                {
                    OnExecutionError(executionToken, startTime, DateTimeOffset.Now, ex, state);
                    throw;
                }
            }
        }