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RaptorDB - The Document Store

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24 Jul 2019CPOL86 min read 2.3M   16.3K   653  
NoSql, JSON based, Document store database with compiled .net map functions and automatic hybrid bitmap indexing and LINQ query filters (now with standalone Server mode, Backup and Active Restore, Transactions, Server side queries, MonoDroid support, HQ-Branch Replication, working in Linux, .net
using System;
using System.Diagnostics;
using System.Collections;
using System.Runtime.InteropServices;
using System.IO;
using System.Text;
using System.Collections.Generic;

namespace RaptorDB
{
    internal class StorageFile<T>
    {
        FileStream _datawrite;
        FileStream _recfilewrite;
        FileStream _recfileread = null;
        FileStream _dataread = null;

        private string _filename = "";
        private string _recfilename = "";
        private int _lastRecordNum = 0;
        private long _lastWriteOffset = 6;
        private object _lock = new object();
        private bool _dirty = false;
        IGetBytes<T> _T = null;

        public static byte[] _fileheader = { (byte)'M', (byte)'G', (byte)'D', (byte)'B',
                                              0, // 4 -- not used,
                                              0  // 5 -- not used
                                           };

        public static byte[] _rowheader = { (byte)'M', (byte)'G', (byte)'R' ,
                                           0,               // 3     [keylen]
                                           0,0,0,0,0,0,0,0, // 4-11  [datetime] 8 bytes = insert time
                                           0,0,0,0,         // 12-15 [data length] 4 bytes
                                           0,               // 16 -- [flags] = 1 : isDeletd:1
                                                            //                 2 : isCompressed:1
                                                            //                 
                                                            //                 
                                           0                // 17 -- [crc] = header crc check
                                       };
        private enum HDR_POS
        {
            KeyLen = 3,
            DateTime = 4,
            DataLength = 12,
            Flags = 16,
            CRC = 17
        }

        public bool SkipDateTime = false;

        public StorageFile(string filename)
        {
            _T = RDBDataType<T>.ByteHandler();
            _filename = filename;
            if (File.Exists(filename) == false)
                _datawrite = new FileStream(filename, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.ReadWrite);
            else
                _datawrite = new FileStream(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite);

            // load rec pointers
            _recfilename = filename.Substring(0, filename.LastIndexOf('.')) + ".mgrec";
            if (File.Exists(_recfilename) == false)
                _recfilewrite = new FileStream(_recfilename, FileMode.CreateNew, FileAccess.Write, FileShare.ReadWrite);
            else
                _recfilewrite = new FileStream(_recfilename, FileMode.Open, FileAccess.Write, FileShare.ReadWrite);

            _recfileread = new FileStream(_recfilename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            _dataread = new FileStream(_filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

            if (_datawrite.Length == 0)
            {
                // new file
                _datawrite.Write(_fileheader, 0, _fileheader.Length);
                _datawrite.Flush();
                _lastWriteOffset = _fileheader.Length;
            }
            else
            {
                _lastWriteOffset = _datawrite.Seek(0L, SeekOrigin.End);
            }
            _lastRecordNum = (int)(_recfilewrite.Length / 8);
            _recfilewrite.Seek(0L, SeekOrigin.End);
        }

        public int Count()
        {
            return (int)(_recfilewrite.Length >> 3);
        }

        #region [  traverse  ]
        //public IEnumerable<KeyValuePair<T, byte[]>> Traverse()
        //{
        //    long offset = 0;
        //    offset = _fileheader.Length;

        //    while (offset < _datawrite.Length)
        //    {
        //        long pointer = offset;
        //        byte[] key;
        //        bool deleted = false;
        //        offset = NextOffset(offset, out key, out deleted);
        //        KeyValuePair<T, byte[]> kv = new KeyValuePair<T, byte[]>(_T.GetObject(key, 0, key.Length), internalReadData(pointer));
        //        if (deleted == false)
        //            yield return kv;
        //    }
        //}

        //private long NextOffset(long curroffset, out byte[] key, out bool isdeleted)
        //{
        //    isdeleted = false;
        //    if (_dataread == null)
        //        _dataread = new FileStream(_filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
        //    {
        //        long next = _dataread.Length;
        //        // seek offset in file
        //        byte[] hdr = new byte[_rowheader.Length];
        //        _dataread.Seek(curroffset, System.IO.SeekOrigin.Begin);
        //        // read header
        //        _dataread.Read(hdr, 0, _rowheader.Length);
        //        key = new byte[hdr[(int)HDR_POS.KeyLen]];
        //        _dataread.Read(key, 0, hdr[(int)HDR_POS.KeyLen]);
        //        // check header
        //        if (CheckHeader(hdr))
        //        {
        //            next = curroffset + hdr.Length + Helper.ToInt32(hdr, (int)HDR_POS.DataLength) + hdr[(int)HDR_POS.KeyLen];
        //            isdeleted = isDeleted(hdr);
        //        }

        //        return next;
        //    }
        //}
        #endregion

        public int WriteData(T key, byte[] data, bool deleted)
        {
            lock (_lock)
            {
                _dirty = true;
                byte[] k = _T.GetBytes(key);
                int kl = k.Length;

                // seek end of file
                long offset = _lastWriteOffset;
                byte[] hdr = CreateRowHeader(kl, (data == null ? 0 : data.Length));
                if (deleted)
                    hdr[(int)HDR_POS.Flags] = (byte)1;
                // write header info
                _datawrite.Write(hdr, 0, hdr.Length);
                // write key
                _datawrite.Write(k, 0, kl);
                if (data != null)
                {
                    // write data block
                    _datawrite.Write(data, 0, data.Length);
                    _lastWriteOffset += data.Length;
                }
                // update pointer
                _lastWriteOffset += hdr.Length;
                _lastWriteOffset += kl;
                // return starting offset -> recno
                int recno = _lastRecordNum++;
                _recfilewrite.Write(Helper.GetBytes(offset, false), 0, 8);
                if (Global.FlushStorageFileImmetiatley)
                {
                    _datawrite.Flush();
                    _recfilewrite.Flush();
                }
                return recno;
            }
        }

        private byte[] CreateRowHeader(int keylen, int datalen)
        {
            byte[] rh = new byte[_rowheader.Length];
            Buffer.BlockCopy(_rowheader, 0, rh, 0, rh.Length);
            rh[3] = (byte)keylen;
            if (SkipDateTime == false)
                Buffer.BlockCopy(Helper.GetBytes(FastDateTime.Now.Ticks, false), 0, rh, 4, 4);
            Buffer.BlockCopy(Helper.GetBytes(datalen, false), 0, rh, 12, 4);

            return rh;
        }

        public byte[] ReadData(int recnum)
        {
            if (recnum >= _lastRecordNum)
                return null;

            lock (_lock)
            {
                if (_dirty)
                {
                    _datawrite.Flush();
                    _recfilewrite.Flush();
                }
                long off = recnum * 8L;
                byte[] b = new byte[8];

                _recfileread.Seek(off, SeekOrigin.Begin);
                _recfileread.Read(b, 0, 8);
                off = Helper.ToInt64(b, 0);
                if (off == 0)// kludge
                    off = 6;

                return internalReadData(off);
            }
        }

        private byte[] internalReadData(long offset)
        {
            // seek offset in file
            byte[] hdr = new byte[_rowheader.Length];
            _dataread.Seek(offset, System.IO.SeekOrigin.Begin);
            // read header
            _dataread.Read(hdr, 0, _rowheader.Length);
            // check header
            if (CheckHeader(hdr))
            {
                // skip key bytes
                _dataread.Seek(hdr[(int)HDR_POS.KeyLen], System.IO.SeekOrigin.Current);
                int dl = Helper.ToInt32(hdr, (int)HDR_POS.DataLength);
                byte[] data = new byte[dl];
                // read data block
                _dataread.Read(data, 0, dl);
                return data;
            }
            else
                throw new Exception("data header error at offset : " + offset + " data file size = " + _dataread.Length);

        }

        private bool CheckHeader(byte[] hdr)
        {
            if (hdr[0] == (byte)'M' && hdr[1] == (byte)'G' && hdr[2] == (byte)'R' && hdr[(int)HDR_POS.CRC] == (byte)0)
                return true;
            return false;
        }

        public void Shutdown()
        {
            FlushClose(_dataread);
            FlushClose(_recfileread);
            FlushClose(_recfilewrite);
            FlushClose(_datawrite);

            _dataread = null;
            _recfileread = null;
            _recfilewrite = null;
            _datawrite = null;
        }

        private void FlushClose(FileStream st)
        {
            if (st != null)
            {
                st.Flush(true);
                st.Close();
            }
        }

        internal T GetKey(int recnum, out bool deleted)
        {
            lock (_lock)
            {
                deleted = false;
                long off = recnum * 8L;
                byte[] b = new byte[8];

                _recfileread.Seek(off, SeekOrigin.Begin);
                _recfileread.Read(b, 0, 8);
                off = Helper.ToInt64(b, 0);

                // seek offset in file
                byte[] hdr = new byte[_rowheader.Length];
                _dataread.Seek(off, System.IO.SeekOrigin.Begin);
                // read header
                _dataread.Read(hdr, 0, _rowheader.Length);

                if (CheckHeader(hdr))
                {
                    deleted = isDeleted(hdr);
                    byte kl = hdr[3];
                    byte[] kbyte = new byte[kl];

                    _dataread.Read(kbyte, 0, kl);
                    return _T.GetObject(kbyte, 0, kl);
                }

                return default(T);
            }
        }

        private bool isDeleted(byte[] hdr)
        {
            return (hdr[(int)HDR_POS.Flags] & (byte)1) > 0;
        }
    }
}

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Architect -
United Kingdom United Kingdom
Mehdi first started programming when he was 8 on BBC+128k machine in 6512 processor language, after various hardware and software changes he eventually came across .net and c# which he has been using since v1.0.
He is formally educated as a system analyst Industrial engineer, but his programming passion continues.

* Mehdi is the 5th person to get 6 out of 7 Platinum's on Code-Project (13th Jan'12)
* Mehdi is the 3rd person to get 7 out of 7 Platinum's on Code-Project (26th Aug'16)

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