| public Read ( int offset, int length ) : byte[] | ||
| offset | int | |
| length | int | |
| return | byte[] | |
/// <summary>
/// Standard and transactional rollback
/// </summary>
public void Rollback()
{
try
{
lock (lock_fs)
{
//Clearing random buffer
if (_randBuf.Count() != 0)
{
usedBufferSize = 0;
_randBuf.Clear();
}
//Restoring Rollback records
byte[] btWork = null;
if (_rollbackCache.Count() > 0)
{
foreach (var rb in _rollbackCache)
{
btWork = new byte[rb.Value.l];
btWork = _fsRollback.Read((int)rb.Value.o, btWork.Length);
//_fsRollback.Position = rb.Value.o;
//_fsRollback.Read(btWork, 0, btWork.Length);
_fsData.Write_ByOffset((int)rb.Key, btWork);
//_fsData.Position = rb.Key;
//_fsData.Write(btWork, 0, btWork.Length);
}
//NET_Flush(_fsData);
//Restoring rhp
eofRollback = 0;
btWork = eofRollback.To_8_bytes_array_BigEndian();
_fsRollbackHelper.Write_ByOffset(0, btWork);
//_fsRollbackHelper.Position = 0;
//_fsRollbackHelper.Write(eofRollback.To_8_bytes_array_BigEndian(), 0, 8);
//NET_Flush(_fsRollbackHelper);
//Clearing rollbackCache
_rollbackCache.Clear();
}
//we dont move eofData, space can be re-used up to next restart (may be root can have this info in next protocols)
//eofData = this._fsData.Length;
}
}
catch (Exception ex)
{
IsOperable = false;
throw DBreezeException.Throw(DBreezeException.eDBreezeExceptions.RESTORE_ROLLBACK_DATA_FAILED, this._fileName, ex);
}
}
/// <summary>
///
/// </summary>
/// <param name="readActual">if actual overwritten data must be used</param>
/// <param name="offset"></param>
/// <returns></returns>
public byte[] Table_Read(bool useCache, long offset, int count)
{
byte[] res = null;
//if (count == 0) //!!! also not necessary, but can be while testing period under exception
// return null;
lock (lock_fs)
{
if (!useCache)
{
//We read exactly what is already saved, without rollback.
//all data must be either in file or in buffer
//we must form resulting byte[]
//Buffer
//Finding first element which is smaller or equal then offset
List <long> bufKeys = new List <long>();
if (_randBuf.Count() > 0)
{
var qkvp = _randBuf.OrderByDescending(r => r.Key).Where(r => r.Key < offset).Take(1).Where(r => (r.Key + r.Value.Length - 1) >= offset);
if (qkvp.Count() > 0)
{
bufKeys.Add(qkvp.FirstOrDefault().Key);
}
foreach (var kvp in _randBuf.OrderBy(r => r.Key).Where(r => r.Key >= offset && r.Key < (offset + count)))
{
bufKeys.Add(kvp.Key);
}
}
//reading full byte[] from original file and putting on top keys
//We use full length of the file
if (offset + count > _fsData.EOF)
{
res = new byte[_fsData.EOF - offset];
}
else
{
res = new byte[count];
}
res = _fsData.Read((int)offset, res.Length);
byte[] btWork = null;
//putting on top
foreach (var bk in bufKeys)
{
btWork = _randBuf[bk];
bool cut = false;
int start = 0;
int stop = btWork.Length;
if (bk < offset)
{
cut = true;
start = Convert.ToInt32(offset - bk);
}
if ((offset + count) < (bk + btWork.Length))
{
cut = true;
stop = Convert.ToInt32(offset + count - bk);
}
if (cut)
{
byte[] tmp = new byte[stop - start];
Buffer.BlockCopy(btWork, start, tmp, 0, tmp.Length);
btWork = tmp;
}
Buffer.BlockCopy(btWork, 0, res, (start > 0) ? 0 : Convert.ToInt32(bk - offset), btWork.Length);
}
}
else
{
//we must use rollback file.
//We can read only up to commited file lengh eofData
List <long> bufKeys = new List <long>();
if (_rollbackCache.Count() > 0)
{
var qkvp = _rollbackCache.OrderByDescending(r => r.Key).Where(r => r.Key < offset).Take(1).Where(r => (r.Key + r.Value.l - 1) >= offset);
if (qkvp.Count() > 0)
{
bufKeys.Add(qkvp.FirstOrDefault().Key);
}
foreach (var kvp in _rollbackCache.OrderBy(r => r.Key).Where(r => r.Key >= offset && r.Key < (offset + count)))
{
bufKeys.Add(kvp.Key);
}
}
//reading full byte[] from original file and putting on top keys
/*
* Transaction with minimum 2 tables. T2 is inserted, reference to T2 KVP is taken, then this reference is saved into T1.
* Commit().
* Commit calls TransactionalCommit for every table sequentially. First it meets table T1, then T2.
* In both tables TransactionalCommit procedures are successfull.
* then Commit procedure for each table calls TransactionalCommitIsFinished (this proc will clear rollback refs and moves eofData for every table).
* First encounters T1 and only then T2.
* ....Somewhere here (between calling T1 and T2 TransactionalCommitIsFinished) starts a parallel thread.
* After T1 TransactionalCommitIsFinished our parallel thread P1 reads data from T1,
* and gets SelectDirect reference to T2 KVP. Then tries to read from not yet TransactionalCommitIsFinished T2.
* and for T2 happens: eofData < offset
*
* To avoid such specific case we use for calculation this._fsData.Length instead of eofData in case if (eofData < offset && TransactionalCommitIsStarted)
* 19.07.2013 10:25
*/
//WAS
//if (offset + count > eofData)
// res = new byte[eofData - offset];
//else
// res = new byte[count];
//////
//NOW
if (offset + count > eofData)
{
if (eofData < offset && TransactionalCommitIsStarted) //NOT FINISHED multi-table COMMIT. SelectDirect case
{
//Probably not finished transaction and SelectDirect case. We return value,
//because at this momont all transaction table have successfully gone through TransactionalCommit() procedure.
if (offset + count > this._fsData.EOF)
{
res = new byte[this._fsData.EOF - offset];
}
else
{
res = new byte[count];
}
}
else
{
res = new byte[eofData - offset];
}
}
else
{
res = new byte[count];
}
///////
res = _fsData.Read((int)offset, res.Length);
byte[] btWork = null;
r rb = null;
//putting on top
foreach (var bk in bufKeys)
{
rb = _rollbackCache[bk];
//reading from rollback
btWork = new byte[rb.l];
btWork = _fsData.Read((int)rb.o, btWork.Length);
bool cut = false;
int start = 0;
int stop = btWork.Length;
if (bk < offset)
{
cut = true;
start = Convert.ToInt32(offset - bk);
}
if ((offset + count) < (bk + btWork.Length))
{
cut = true;
stop = Convert.ToInt32(offset + count - bk);
}
if (cut)
{
byte[] tmp = new byte[stop - start];
Buffer.BlockCopy(btWork, start, tmp, 0, tmp.Length);
btWork = tmp;
}
Buffer.BlockCopy(btWork, 0, res, (start > 0) ? 0 : Convert.ToInt32(bk - offset), btWork.Length);
}
}
}
return(res);
}
