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;
}
}
}