C# 대용량 파일에서 마지막 라인 읽기

 

public static string ReadEndTokens(string path, Int64 numberOfTokens, Encoding encoding, string tokenSeparator)
        {

            int sizeOfChar = encoding.GetByteCount("\n");
            byte[] buffer = encoding.GetBytes(tokenSeparator);


            using (FileStream fs = new FileStream(path, FileMode.Open))
            {
                Int64 tokenCount = 0;
                Int64 endPosition = fs.Length / sizeOfChar;

                for (Int64 position = sizeOfChar; position < endPosition; position += sizeOfChar)
                {
                    fs.Seek(-position, SeekOrigin.End);
                    fs.Read(buffer, 0, buffer.Length);

                    if (encoding.GetString(buffer) == tokenSeparator)
                    {
                        tokenCount++;
                        if (tokenCount == numberOfTokens)
                        {
                            byte[] returnBuffer = new byte[fs.Length - fs.Position];
                            fs.Read(returnBuffer, 0, returnBuffer.Length);
                            return encoding.GetString(returnBuffer);
                        }
                    }
                }

                // handle case where number of tokens in file is less than numberOfTokens
                fs.Seek(0, SeekOrigin.Begin);
                buffer = new byte[fs.Length];
                fs.Read(buffer, 0, buffer.Length);
                return encoding.GetString(buffer);
            }
        }