/// <summary>
/// Raised the <see cref="OnChanged"/> event.
/// </summary>
/// <param name="contact"></param>
/// <param name="operation"></param>
private void RaiseOnChanged(IContact contact, BucketOperation operation)
{
if (OnChanged != null)
{
OnChanged(contact, operation);
}
}
/// <summary>
/// Raised the <see cref="OnChanged"/> event.
/// </summary>
/// <param name="contact"></param>
/// <param name="operation"></param>
private void RaiseOnChanged(IContact contact, BucketOperation operation)
{
if (contact == null)
{
throw new ArgumentNullException("contact");
}
if (OnChanged != null)
{
OnChanged(contact, operation);
}
}
/// <summary>
/// Adds an <see cref="IContact" /> to the <see cref="Bucket" /> and maintains the sorting.
/// </summary>
/// <param name="contact"></param>
public void Add(IContact contact)
{
if (contact == null)
{
throw new ArgumentNullException("contact");
}
// Prevent a Kademlia from registering himself as a contact
if (contact.Equals(_owner.Contact))
{
return;
}
BucketOperation operation = BucketOperation.Add;
IContact firstContact = null;
BucketOperation operationFirstContact = BucketOperation.Update;
try
{
// Obtain lock
_contactsReaderWriterLock.EnterWriteLock();
// 2 cases:
// 1. contact is in list
// 2. contact is not in list
if (_contacts.Remove(contact))
{
operation = BucketOperation.Update;
}
// Check if there is space in the bucket
// If we just successfully removed the bucket we know it is an update operation,
// else it will be an add operation
if (_contacts.Count < Constants.K)
{
// There is space
_contacts.Add(contact);
}
else
{
// There is not space, try to contact the least recently seen contact (located at the head)
firstContact = _contacts.First();
bool replyReceived = false;
try
{
using (NodeProxy nodeProxy = new NodeProxy(_owner, firstContact, false))
{
replyReceived = nodeProxy.Context.Ping();
}
}
catch (Exception) { { } }
// Remove the least recently seen contact from head
_contacts.Remove(firstContact);
if (replyReceived)
{
// It responded, so move it to the tail of the list, and issue an update event
operationFirstContact = BucketOperation.Update;
_contacts.Add(firstContact);
// This means that we discard the new contact
operation = BucketOperation.Discard;
}
else
{
// The least recently seen contact did not respond, so issue a remove event
// and add the new contact to the tail, as it is the most recently seen
operationFirstContact = BucketOperation.Remove;
_contacts.Add(contact);
// This means that we add the new contact
operation = BucketOperation.Add;
}
}
}
catch (Exception ex)
{
Log.Error(ex);
}
finally
{
// Release lock
_contactsReaderWriterLock.ExitWriteLock();
}
if (firstContact != null)
{
RaiseOnChanged(firstContact, operationFirstContact);
}
RaiseOnChanged(contact, operation);
}
