private void ExecuteInternal()
{
Debug.Assert(_operation >= Operation.Read && _operation <= Operation.WriteGather);
long result = 0;
Exception?exception = null;
try
{
// This is the operation's last chance to be canceled.
if (_cancellationToken.IsCancellationRequested)
{
exception = new OperationCanceledException(_cancellationToken);
}
else
{
switch (_operation)
{
case Operation.Read:
Memory <byte> writableSingleSegment = MemoryMarshal.AsMemory(_singleSegment);
result = RandomAccess.ReadAtOffset(_fileHandle, writableSingleSegment.Span, _fileOffset);
break;
case Operation.Write:
RandomAccess.WriteAtOffset(_fileHandle, _singleSegment.Span, _fileOffset);
break;
case Operation.ReadScatter:
Debug.Assert(_readScatterBuffers != null);
result = RandomAccess.ReadScatterAtOffset(_fileHandle, _readScatterBuffers, _fileOffset);
break;
case Operation.WriteGather:
Debug.Assert(_writeGatherBuffers != null);
RandomAccess.WriteGatherAtOffset(_fileHandle, _writeGatherBuffers, _fileOffset);
break;
}
}
}
catch (Exception e)
{
exception = e;
}
finally
{
_operation = Operation.None;
_context = null;
_cancellationToken = default;
_singleSegment = default;
_readScatterBuffers = null;
_writeGatherBuffers = null;
}
if (exception == null)
{
_source.SetResult(result);
}
else
{
_source.SetException(exception);
}
}