public void WriteNewLink(int pageId, out int expiredPage)
{
lock (_lock)
{
expiredPage = -1;
if (_linkA.PageId < 0)
{
// A has never been set
_linkA = new PageLink
{
PageId = pageId,
Version = new MonotonicByte(0)
};
return;
}
if (_linkB.PageId < 0)
{
// B has never been set
_linkB = new PageLink
{
PageId = pageId,
Version = _linkA.Version.GetNext()
};
return;
}
if (_linkA.Version == _linkB.Version)
{
throw new Exception("VersionedLink.WriteNewLink: option table versions invalid");
}
if (_linkA.Version > _linkB.Version)
{
// B is older. Replace it.
expiredPage = _linkB.PageId;
_linkB = new PageLink
{
PageId = pageId,
Version = _linkA.Version.GetNext()
};
return;
}
// A is older. Replace it.
expiredPage = _linkA.PageId;
_linkA = new PageLink
{
PageId = pageId,
Version = _linkB.Version.GetNext()
};
}
}
private void WriteLink([NotNull] BinaryWriter w, PageLink link)
{
if (link != null)
{
w.Write((byte)link.Version.Value);
w.Write(link.PageId);
}
else
{
w.Write((byte)0);
w.Write(-1);
}
}
/// <inheritdoc />
public void Defrost(Stream source)
{
lock (_lock)
{
if (source == null || source.Length < ByteSize)
{
throw new Exception("VersionedLink.FromBytes: data was too short.");
}
var r = new BinaryReader(source);
_linkA = new PageLink
{
Version = new MonotonicByte(r.ReadByte()),
PageId = r.ReadInt32()
};
_linkB = new PageLink
{
Version = new MonotonicByte(r.ReadByte()),
PageId = r.ReadInt32()
};
}
}
public VersionedLink()
{
_linkA = PageLink.InvalidLink();
_linkB = PageLink.InvalidLink();
}
