/// <summary>
/// Discards the snapshot any changes made after the snapshot was taken are kept.
/// </summary>
public void ForgetSnapshot()
{
if (_diffStream == null)
{
throw new InvalidOperationException("No snapshot");
}
byte[] buffer = new byte[8192];
foreach (var extent in _diffExtents)
{
_diffStream.Position = extent.Start;
_baseStream.Position = extent.Start;
int totalRead = 0;
while (totalRead < extent.Length)
{
int toRead = (int)Math.Min(extent.Length - totalRead, buffer.Length);
int read = _diffStream.Read(buffer, 0, toRead);
_baseStream.Write(buffer, 0, read);
totalRead += read;
}
}
_diffStream = null;
_diffExtents = null;
}
/// <summary>
/// Reverts to a previous snapshot, discarding any changes made to the stream.
/// </summary>
public void RevertToSnapshot()
{
if (_diffStream == null)
{
throw new InvalidOperationException("No snapshot");
}
_diffStream = null;
_diffExtents = null;
_position = _savedPosition;
}
/// <summary>
/// Takes a snapshot of the current stream contents.
/// </summary>
public void Snapshot()
{
if (_diffStream != null)
{
throw new InvalidOperationException("Already have a snapshot");
}
_savedPosition = _position;
_diffExtents = new List <StreamExtent>();
_diffStream = new SparseMemoryStream();
_diffStream.SetLength(_baseStream.Length);
}
/// <summary>
/// Disposes of this instance.
/// </summary>
/// <param name="disposing"><c>true</c> if called from Dispose(), else <c>false</c>.</param>
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (_baseStreamOwnership == Ownership.Dispose && _baseStream != null)
{
_baseStream.Dispose();
}
_baseStream = null;
if (_diffStream != null)
{
_diffStream.Dispose();
}
_diffStream = null;
}
base.Dispose(disposing);
}
