public DiskService(EngineSettings settings, int[] memorySegmentSizes)
{
_cache = new MemoryCache(memorySegmentSizes);
// get new stream factory based on settings
_dataFactory = settings.CreateDataFactory();
_logFactory = settings.CreateLogFactory();
// create stream pool
_dataPool = new StreamPool(_dataFactory, false);
_logPool = new StreamPool(_logFactory, true);
var isNew = !_dataFactory.Exists() || _dataFactory.GetLength() == 0L;
// create lazy async writer queue for log file
_queue = new Lazy <DiskWriterQueue>(() => new DiskWriterQueue(_logPool.Writer));
// create new database if not exist yet
if (isNew)
{
LOG($"creating new database: '{Path.GetFileName(_dataFactory.Name)}'", "DISK");
this.Initialize(_dataPool.Writer, settings.Collation, settings.InitialSize);
}
// if not readonly, force open writable datafile
if (settings.ReadOnly == false)
{
var dummy = _dataPool.Writer.CanRead;
}
// get initial data file length
_dataLength = _dataFactory.GetLength() - PAGE_SIZE;
// get initial log file length
if (_logFactory.Exists())
{
_logLength = _logFactory.GetLength() - PAGE_SIZE;
}
else
{
_logLength = -PAGE_SIZE;
}
}