/// <summary>
/// Prevents further modification to graph and indicates that the graph
/// should switch to being read-optimized
/// </summary>
public void Seal()
{
using (m_globalLock.AcquireWriteLock())
{
m_state = MutableGraphState.Sealed;
// Remove the edge set which is only needed for deduplication when adding
m_edgeSet = null;
}
}
/// <summary>
/// Takes a read or write lock for the given operation depending on the state of the graph .
/// For instance, there can be concurrent edge additions while in the Mutating state for the same node/lock,
/// but enumeration will take an exclusive lock to ensure it gets consistent information while graph is in Mutating state.
/// Once the graph enters the sealed state, enumerations allow sharing. Therefore, operations that enumerate edges will pass
/// sharingState = Sealed while the AddEdge operation passes sharingState = Mutating.
/// </summary>
/// <param name="rwLock">the read write lock to acquire read or write access from</param>
/// <param name="sharingState">specifies the state for which concurrent access is allowed for the operation protected by this lock</param>
/// <returns>the read or write lock (as a switch read write lock)</returns>
private SwitchReadWriteLock AcquireLockForState(ReadWriteLock rwLock, MutableGraphState sharingState)
{
if (!rwLock.IsValid)
{
return(default(SwitchReadWriteLock));
}
using (m_globalLock.HasExclusiveAccess ? ReadLock.Invalid : m_globalLock.AcquireReadLock())
{
return(new SwitchReadWriteLock(rwLock, isSharing: sharingState == m_state));
}
}
