public void Initialize()
{
if (!File.Exists(_storePath))
{
_storeStream = new FileStream(_storePath, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
_firstNotAllocated = SectorIndex.First;
_log?.Log(LogSeverity.Info, $"Empty file created: {_storePath}.");
}
else
{
_storeStream = new FileStream(_storePath, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
}
// Number of sectors is inferred from the file size.
var info = new FileInfo(_storePath);
_firstNotAllocated = SectorIndex.OffsetInBytes(info.Length, _sectorSizeInBytes);
if (!File.Exists(_hotPath))
{
_hotStream = new FileStream(_hotPath, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
_log?.Log(LogSeverity.Info, $"Empty file created: {_hotPath}.");
}
else
{
_hotStream = new FileStream(_hotPath, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
TryRecovery();
}
}
public void Initialize()
{
// recovery on edge crash
if (File.Exists(TmpStorePath) && !File.Exists(_storePath))
{
File.Move(TmpStorePath, _storePath);
_log.Log(LogSeverity.Warning, $"File recovered: {TmpStorePath}");
}
// Number of sectors is inferred from the file size.
_firstNotAllocated = SectorIndex.First;
if (File.Exists(_storePath))
{
var info = new FileInfo(_storePath);
_firstNotAllocated = SectorIndex.OffsetInBytes(info.Length, _sectorSizeInBytes);
}
// hot stream does not apply to volatile store
if (!File.Exists(_storePath))
{
_storeStream = new FileStream(_storePath, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
_log?.Log(LogSeverity.Info, $"Empty file created: {_storePath}.");
_firstNotAllocated = SectorIndex.First;
_memoryStream = new MemoryStream();
}
else
{
_storeStream = new FileStream(_storePath, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
_memoryStream = new MemoryStream((int)_storeStream.Length);
_storeStream.CopyTo(_memoryStream);
}
}
/// <summary>
/// Recover a halfway written sector.
/// </summary>
/// <remarks>
/// TODO: verify this method does what it is supposed to do, after replacing TryRead with a Read that throws exceptions,
/// instead of returning a bool.
/// </remarks>
private void TryRecovery()
{
try
{
var offset = _sector.Read(_hotStream); // hotstream is valid
var deducedIndex = SectorIndex.OffsetInBytes(offset, _sectorSizeInBytes);
try
{
//try read last recorded sector
Read(deducedIndex);
// reach here means that both streams are ok
}
catch (SectorOperationException)
{
// something went wrong in storeStream
_hotStream.Seek(0, SeekOrigin.Begin);
_sector.Read(_hotStream, offset);
// reach here means that hostream is ok
// copying '_hotstream' back to '_storeStream'
_storeStream.Seek(deducedIndex.ByteIndex(_sectorSizeInBytes), SeekOrigin.Begin);
_sector.Write(_storeStream, deducedIndex.ByteIndex(_sectorSizeInBytes));
// TODO: add log to indicate successful recovery.
}
}
catch (SectorOperationException)
{
// hotstream invalid
// normally thanks to double writing, main store stream is valid
_log?.Log(LogSeverity.Warning, "Hotstream error when trying to recover sector store.");
throw;
}
}