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RaptorDB - The Key Value Store V2

, 10 Oct 2013
Even faster Key/Value store nosql embedded database engine utilizing the new MGIndex data structure with MurMur2 Hashing and WAH Bitmap indexes for duplicates. (with MonoDroid support)
RaptorDB_v2.0.zip
RaptorDB
DataTypes
Indexes
Properties
Storage
testing
UnitTests
Properties
UnitTests.nunit
RaptorDB_v2.1.zip
UnitTests.nunit
RaptorDB_v2.2.zip
UnitTests.nunit
RaptorDB_v2.3.zip
UnitTests.nunit
RaptorDB_v2.4.zip
UnitTests.nunit
RaptorDB_v2.5.zip
UnitTests.nunit
RaptorDB_v2.6.zip
UnitTests.nunit
RaptorDB_v2.7.0.zip
UnitTests.nunit
RaptorDB_v2.7.5.zip
UnitTests.nunit
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Threading;
using System.Collections;

namespace RaptorDB
{
    internal class BitmapIndex
    {
        public BitmapIndex(string path, string filename)
        {
            _FileName = Path.GetFileNameWithoutExtension(filename);
            _Path = path;
            if (_Path.EndsWith(Path.DirectorySeparatorChar.ToString()) == false)
                _Path += Path.DirectorySeparatorChar.ToString();

            Initialize();
        }

        class L : IDisposable
        {
            BitmapIndex _sc;
            public L(BitmapIndex sc)
            {
                _sc = sc;
                _sc.CheckInternalOP();
            }
            void IDisposable.Dispose()
            {
                _sc.Done();
            }
        }
        private string _recExt = ".mgbmr";
        private string _bmpExt = ".mgbmp";
        private string _FileName = "";
        private string _Path = "";
        private FileStream _bitmapFileWriteOrg;
        private BufferedStream _bitmapFileWrite;
        private FileStream _bitmapFileRead;
        private FileStream _recordFileRead;
        private FileStream _recordFileWriteOrg;
        private BufferedStream _recordFileWrite;
        private long _lastBitmapOffset = 0;
        private int _lastRecordNumber = 0;
        private SafeDictionary<int, WAHBitArray> _cache = new SafeDictionary<int, WAHBitArray>();
        private SafeDictionary<int, long> _offsetCache = new SafeDictionary<int, long>();
        private ILog log = LogManager.GetLogger(typeof(BitmapIndex));
        private bool _optimizing = false;
        private bool _shutdownDone = false;
        private Queue _que = new Queue();

        #region [  P U B L I C  ]
        public void Shutdown()
        {
            using (new L(this))
            {
                log.Debug("Shutdown BitmapIndex");

                InternalShutdown();
            }
        }

        public int GetFreeRecordNumber()
        {
            using (new L(this))
            {
                int i = _lastRecordNumber++;

                _cache.Add(i, new WAHBitArray());
                return i;
            }
        }

        public void Commit(bool freeMemory)
        {
            using (new L(this))
            {
                int[] keys = _cache.Keys();
                Array.Sort(keys);

                foreach (int k in keys)
                {
                    var bmp = _cache[k];
                    if (bmp.isDirty)
                    {
                        SaveBitmap(k, bmp);
                        bmp.FreeMemory();
                        bmp.isDirty = false;
                    }
                }
                Flush();
                if (freeMemory)
                {
                    _cache = new SafeDictionary<int, WAHBitArray>();
                }
            }
        }

        public void SetDuplicate(int bitmaprecno, int record)
        {
            using (new L(this))
            {
                WAHBitArray ba = null;

                ba = GetBitmap(bitmaprecno);

                ba.Set(record, true);
            }
        }

        public WAHBitArray GetBitmap(int recno)
        {
            using (new L(this))
            {
                return internalGetBitmap(recno);
            }
        }

        private object _oplock = new object();
        public void Optimize()
        {
            lock (_oplock)
                lock (_readlock)
                    lock (_writelock)
                    {
                        _optimizing = true;
                        while (_que.Count > 0) Thread.SpinWait(1);
                        Flush();

                        if (File.Exists(_Path + _FileName + "$" + _bmpExt))
                            File.Delete(_Path + _FileName + "$" + _bmpExt);

                        if (File.Exists(_Path + _FileName + "$" + _recExt))
                            File.Delete(_Path + _FileName + "$" + _recExt);

                        FileStream _newrec = new FileStream(_Path + _FileName + "$" + _recExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
                        FileStream _newbmp = new FileStream(_Path + _FileName + "$" + _bmpExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);

                        long newoffset = 0;
                        int c = (int)(_recordFileRead.Length / 8);
                        for (int i = 0; i < c; i++)
                        {
                            long offset = ReadRecordOffset(i);

                            byte[] b = ReadBMPData(offset);
                            if (b == null)
                            {
                                _optimizing = false;
                                throw new Exception("bitmap index file is corrupted");
                            }

                            _newrec.Write(Helper.GetBytes(newoffset, false), 0, 8); 
                            newoffset += b.Length;
                            _newbmp.Write(b, 0, b.Length);

                        }
                        _newbmp.Flush();
                        _newbmp.Close();
                        _newrec.Flush();
                        _newrec.Close();

                        InternalShutdown();

                        File.Delete(_Path + _FileName + _bmpExt);
                        File.Delete(_Path + _FileName + _recExt);
                        File.Move(_Path + _FileName + "$" + _bmpExt, _Path + _FileName + _bmpExt);
                        File.Move(_Path + _FileName + "$" + _recExt, _Path + _FileName + _recExt);

                        Initialize();
                        _optimizing = false;
                    }
        }
        #endregion


        #region [  P R I V A T E  ]
        private byte[] ReadBMPData(long offset)
        {
            _bitmapFileRead.Seek(offset, SeekOrigin.Begin);

            byte[] b = new byte[8];

            _bitmapFileRead.Read(b, 0, 8);
            if (b[0] == (byte)'B' && b[1] == (byte)'M' && b[7] == 0)
            {
                int c = Helper.ToInt32(b, 2) * 4 + 8;
                byte[] data = new byte[c];
                _bitmapFileRead.Seek(offset, SeekOrigin.Begin);
                _bitmapFileRead.Read(data, 0, c);
                return data;
            }
            return null;
        }

        private long ReadRecordOffset(int recnum)
        {
            byte[] b = new byte[8];
            long off = ((long)recnum) * 8;
            _recordFileRead.Seek(off, SeekOrigin.Begin);
            _recordFileRead.Read(b, 0, 8);
            return Helper.ToInt64(b, 0);
        }

        private void Initialize()
        {
            _recordFileRead = new FileStream(_Path + _FileName + _recExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
            _recordFileWriteOrg = new FileStream(_Path + _FileName + _recExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
            _recordFileWrite = new BufferedStream(_recordFileWriteOrg);

            _bitmapFileRead = new FileStream(_Path + _FileName + _bmpExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
            _bitmapFileWriteOrg = new FileStream(_Path + _FileName + _bmpExt, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
            _bitmapFileWrite = new BufferedStream(_bitmapFileWriteOrg);

            _bitmapFileWrite.Seek(0L, SeekOrigin.End);
            _lastBitmapOffset = _bitmapFileWrite.Length;
            _lastRecordNumber = (int)(_recordFileRead.Length / 8);
            _shutdownDone = false;
        }

        private void InternalShutdown()
        {
            bool d1 = false;
            bool d2 = false;

            if (_shutdownDone == false)
            {
                Flush();
                if (_recordFileWrite.Length == 0) d1 = true;
                if (_bitmapFileWrite.Length == 0) d2 = true;
                _recordFileRead.Close();
                _bitmapFileRead.Close();
                _bitmapFileWriteOrg.Close();
                _recordFileWriteOrg.Close();
                _recordFileWrite.Close();
                _bitmapFileWrite.Close();
                if (d1)
                    File.Delete(_Path + _FileName + _recExt);
                if (d2)
                    File.Delete(_Path + _FileName + _bmpExt);
                _recordFileWrite = null;
                _recordFileRead = null;
                _bitmapFileRead = null;
                _bitmapFileWrite = null;
                _recordFileRead = null;
                _recordFileWrite = null;
                _shutdownDone = true;
            }
        }

        private void Flush()
        {
            if (_shutdownDone)
                return;
            if (_recordFileWrite != null)
                _recordFileWrite.Flush();
            if (_bitmapFileWrite != null)
                _bitmapFileWrite.Flush();
            if (_recordFileRead != null)
                _recordFileRead.Flush();
            if (_bitmapFileRead != null)
                _bitmapFileRead.Flush();
            if (_bitmapFileWriteOrg != null)
                _bitmapFileWriteOrg.Flush();
            if (_recordFileWriteOrg != null)
                _recordFileWriteOrg.Flush();
        }

        private object _readlock = new object();
        private WAHBitArray internalGetBitmap(int recno)
        {
            lock (_readlock)
            {
                WAHBitArray ba = new WAHBitArray();
                if (recno == -1)
                    return ba;

                if (_cache.TryGetValue(recno, out ba))
                {
                    return ba;
                }
                else
                {
                    long offset = 0;
                    if (_offsetCache.TryGetValue(recno, out offset) == false)
                    {
                        offset = ReadRecordOffset(recno);
                        _offsetCache.Add(recno, offset);
                    }
                    ba = LoadBitmap(offset);

                    _cache.Add(recno, ba);

                    return ba;
                }
            }
        }

        private object _writelock = new object();
        private void SaveBitmap(int recno, WAHBitArray bmp)
        {
            lock (_writelock)
            {
                long offset = SaveBitmapToFile(bmp);
                long v;
                if (_offsetCache.TryGetValue(recno, out v))
                    _offsetCache[recno] = offset;
                else
                    _offsetCache.Add(recno, offset);

                long pointer = ((long)recno) * 8;
                _recordFileWrite.Seek(pointer, SeekOrigin.Begin);
                byte[] b = new byte[8];
                b = Helper.GetBytes(offset, false);
                _recordFileWrite.Write(b, 0, 8);
            }
        }

        //-----------------------------------------------------------------
        // BITMAP FILE FORMAT
        //    0  'B','M'
        //    2  uint count = 4 bytes
        //    6  Bitmap type :
        //                0 = int record list   
        //                1 = uint bitmap
        //                2 = rec# indexes
        //    7  '0'
        //    8  uint data
        //-----------------------------------------------------------------
        private long SaveBitmapToFile(WAHBitArray bmp)
        {
            long off = _lastBitmapOffset;
            WAHBitArray.TYPE t;
            uint[] bits = bmp.GetCompressed(out t);

            byte[] b = new byte[bits.Length * 4 + 8];
            // write header data
            b[0] = ((byte)'B');
            b[1] = ((byte)'M');
            Buffer.BlockCopy(Helper.GetBytes(bits.Length, false), 0, b, 2, 4);

            b[6] = (byte)t;
            b[7] = (byte)(0);

            for (int i = 0; i < bits.Length; i++)
            {
                byte[] u = Helper.GetBytes((int)bits[i], false);
                Buffer.BlockCopy(u, 0, b, i * 4 + 8, 4);
            }
            _bitmapFileWrite.Write(b, 0, b.Length);
            _lastBitmapOffset += b.Length;
            return off;
        }

        private WAHBitArray LoadBitmap(long offset)
        {
            WAHBitArray bc = new WAHBitArray();
            if (offset == -1)
                return bc;

            List<uint> ar = new List<uint>();
            WAHBitArray.TYPE type = WAHBitArray.TYPE.WAH;
            FileStream bmp = _bitmapFileRead;
            {
                bmp.Seek(offset, SeekOrigin.Begin);

                byte[] b = new byte[8];

                bmp.Read(b, 0, 8);
                if (b[0] == (byte)'B' && b[1] == (byte)'M' && b[7] == 0)
                {
                    type = (WAHBitArray.TYPE)Enum.ToObject(typeof(WAHBitArray.TYPE), b[6]);
                    int c = Helper.ToInt32(b, 2);
                    byte[] buf = new byte[c * 4];
                    bmp.Read(buf, 0, c * 4);
                    for (int i = 0; i < c; i++)
                    {
                        ar.Add((uint)Helper.ToInt32(buf, i * 4));
                    }
                }
            }
            bc = new WAHBitArray(type, ar.ToArray());

            return bc;
        }

        private void CheckInternalOP()
        {
            if (_optimizing)
                lock (_oplock) ; // yes! this is good
            _que.Enqueue(1);
        }

        private void Done()
        {
            if (_que.Count > 0)
                _que.Dequeue();
        }
        #endregion

        internal void FreeMemory()
        {
            try
            {
                List<int> free = new List<int>();
                foreach (var b in _cache)
                {
                    if (b.Value.isDirty == false)
                        free.Add(b.Key);
                }
                log.Debug("releasing bmp count = " + free.Count + " out of " + _cache.Count);
                foreach (int i in free)
                    _cache.Remove(i);
            }
            catch { }
        }
    }
}

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

About the Author

Mehdi Gholam
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 Platinums on CodeProject (13th Jan'12)

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