/*
* Copyright (c) 2024 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Data.Caching.Extensions
* File: NodeDiscoveryCollection.cs
*
* NodeDiscoveryCollection.cs is part of VNLib.Data.Caching.Extensions which is part
* of the larger VNLib collection of libraries and utilities.
*
* VNLib.Data.Caching.Extensions is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Data.Caching.Extensions is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using VNLib.Utils.Extensions;
namespace VNLib.Data.Caching.Extensions.Clustering
{
///
/// Represents a collection of available cache nodes from a discovery process
///
public sealed class NodeDiscoveryCollection(StrongBox? selfId) : INodeDiscoveryCollection
{
private LinkedList _peers = new();
///
/// Manually adds nodes to the collection that were not discovered through the discovery process
///
/// The nodes to add
public void AddManualNodes(IEnumerable nodes)
{
//Get only the nodes that are not already in the collection
IEnumerable newPeers = nodes.Except(_peers);
//Add them to the end of the collection
foreach (CacheNodeAdvertisment peer in newPeers)
{
_peers.AddLast(peer);
}
}
///
/// Removes a vector of nodes from the internal collection
///
/// The vector containg nodes to remove from the collection
public void RemoveManualNodes(IEnumerable nodes) => nodes.ForEach(n => _peers.Remove(n));
///
public INodeDiscoveryEnumerator BeginDiscovery() => new NodeEnumerator(new(), selfId?.Value);
///
public INodeDiscoveryEnumerator BeginDiscovery(IEnumerable initialPeers)
{
ArgumentNullException.ThrowIfNull(initialPeers);
//Init new enumerator with the initial peers
return new NodeEnumerator(new(initialPeers), selfId?.Value);
}
///
public void CompleteDiscovery(INodeDiscoveryEnumerator enumerator)
{
ArgumentNullException.ThrowIfNull(enumerator);
//Capture all nodes from the enumerator and store them as our current peers
_peers = (enumerator as NodeEnumerator)!.Peers;
}
///
public CacheNodeAdvertisment[] GetAllNodes() => _peers.ToArray();
private sealed record class NodeEnumerator(LinkedList Peers, string? SelfNodeId) : INodeDiscoveryEnumerator
{
private bool isInit;
//Keep track of the current node in the collection so we can move down the list
private LinkedListNode? _currentNode;
public CacheNodeAdvertisment Current => _currentNode?.Value;
object IEnumerator.Current => _currentNode?.Value;
///
public bool MoveNext()
{
if (!isInit)
{
_currentNode = Peers.First;
isInit = true;
}
else
{
//Move to the next peer in the collection
_currentNode = _currentNode?.Next;
}
return _currentNode?.Value != null;
}
///
public void OnPeerDiscoveryComplete(IEnumerable discoveredPeers)
{
//Get only the peers from the discovery that are not already in the collection, or ourselves
IEnumerable newPeers = discoveredPeers.Except(Peers);
if (!string.IsNullOrWhiteSpace(SelfNodeId))
{
//remove ourselves from the list
newPeers = newPeers.Where(p => !SelfNodeId.Equals(p.NodeId, StringComparison.OrdinalIgnoreCase));
}
//Add them to the end of the collection
foreach (CacheNodeAdvertisment ad in newPeers)
{
Peers.AddLast(ad);
}
}
public void Reset()
{
//Go to the first node
_currentNode = Peers.First;
}
public void Dispose()
{ }
}
}
}