public int AcquireLifetimeToken()
{
if (m_zeroReferencesLeft)
{
throw new InvalidOperationException(Res.TokenCountZero);
}
int next;
lock (m_lifetimeTokens)
{
// Lazily initialize m_random for perf.
if (m_random == null)
{
m_random = new Random();
}
next = m_random.Next();
while (m_lifetimeTokens.Contains(next))
{
next = m_random.Next();
}
m_lifetimeTokens.Add(next);
if (m_lifetimeTokens.Count == 1)
{
// Register as a sponsor the first time a token is aquired.
// need to do this here instead of in InitializeLifetimeService because of a bug in remoting
// involving security.
RegisterAsSponsor();
// Increment ref count on appdomain owner if needed
IContract owner = ContractHandle.AppDomainOwner(AppDomain.CurrentDomain);
if (owner != null && owner != this)
{
m_tokenOfAppdomainOwner = owner.AcquireLifetimeToken();
}
}
}
return(next);
}
public void RevokeLifetimeToken(int token)
{
lock (m_lifetimeTokens)
{
if (!m_lifetimeTokens.Remove(token))
{
throw new InvalidOperationException(Res.LifetimeTokenNotFound);
}
if (m_lifetimeTokens.Count == 0)
{
m_zeroReferencesLeft = true;
// hook to allow subclasses to clean up
OnFinalRevoke();
IContract owner = ContractHandle.AppDomainOwner(AppDomain.CurrentDomain);
if (owner != null)
{
if (owner == this)
{
// Create a separate thread to unload this appdomain, because we
// cannot shut down an appdomain from the Finalizer thread (though there
// is a bug that allows us to do so after the first appdomain has been
// unloaded, but let's not rely on that).
// We can consider using an threadpool thread to do this, but that would add
// test burden.
SecurityPermission permission = new SecurityPermission(SecurityPermissionFlag.ControlThread);
permission.Assert();
System.Threading.ThreadStart threadDelegate = new System.Threading.ThreadStart(AppDomainUnload);
System.Threading.Thread unloaderThread = new System.Threading.Thread(threadDelegate);
unloaderThread.Start();
}
else
{
owner.RevokeLifetimeToken(m_tokenOfAppdomainOwner);
}
}
}
}
}