/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="self"></param>
/// <param name="protocol"></param>
/// <param name="k"></param>
public KFixedRoutingTable(TKNodeId self, IKNodeProtocol <TKNodeId, TKNodeData> protocol, int k = 20)
{
this.self = self;
this.protocol = protocol;
this.k = k;
if (self.DistanceSize % 8 != 0)
{
throw new ArgumentException("NodeId must have a distance size which is a multiple of 8.");
}
buckets = new KBucket <TKNodeId, TKNodeData> [self.DistanceSize];
for (var i = 0; i < buckets.Length; i++)
{
buckets[i] = new KBucket <TKNodeId, TKNodeData>(k);
}
}
/// <summary>
/// Updates the position of the node in the bucket.
/// </summary>
/// <typeparam name="TKNetwork"></typeparam>
/// <param name="nodeId"></param>
/// <param name="nodeData"></param>
/// <param name="nodeEvents"></param>
/// <param name="protocol"></param>
/// <param name="cancellationToken"></param>
internal async ValueTask TouchAsync(TKNodeId nodeId, TKNodeData nodeData, IKNodeEvents nodeEvents, IKNodeProtocol <TKNodeId, TKNodeData> protocol, CancellationToken cancellationToken)
{
var lk = rw.BeginUpgradableReadLock();
try
{
var i = GetNode(nodeId);
if (i != null)
{
using (rw.BeginWriteLock())
{
// item already exists, move to tail
l.Remove(i);
l.AddLast(i.Value);
}
}
else if (l.Count < k)
{
using (rw.BeginWriteLock())
{
// item does not exist, but bucket has room, insert at tail
l.AddLast(new KBucketItem <TKNodeId, TKNodeData>(nodeId, nodeData, nodeEvents));
}
}
else
{
// item does not exist, but bucket does not have room, ping first entry
var n = l.First;
// start ping, check for async completion
KNodePingResponse r;
var t = protocol.PingAsync(n.Value.Id, n.Value.Data, cancellationToken);
// completed synchronously (or immediately)
if (t.IsCompleted)
{
r = t.Result;
}
else
{
// temporarily release lock and wait for completion
lk.Dispose();
r = await t;
lk = rw.BeginUpgradableReadLock();
}
// was able to successfully ping the node
if (r.Status == KNodeResponseStatus.OK)
{
// entry had response, move to tail, discard new entry
if (l.Count > 1)
{
using (rw.BeginWriteLock())
{
// remove from list if not already done (async operation could have overlapped)
if (n.List != null)
{
l.Remove(n);
}
// node goes to end
l.AddLast(n.Value);
}
}
}
else
{
using (rw.BeginWriteLock())
{
// first entry had no response, remove, insert new at tail
l.Remove(n);
l.AddLast(new KBucketItem <TKNodeId, TKNodeData>(nodeId, nodeData, nodeEvents));
}
}
}
}
finally
{
lk.Dispose();
}
}
