Ejemplo n.º 1
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        private void NodeListUpdated(Node node, NodeUpdateAction updateAction)
        {
            //not interested in any non-active nodes
            //other states usually happen when a node comes up online only
            if (!(node.NodeState == NodeState.Active))
                return;

            if (updateAction == NodeUpdateAction.Removed)
                _consistentHash.RemoveItem(node.EndPoint.ToString());
            else if ((updateAction == NodeUpdateAction.Added) || (updateAction == NodeUpdateAction.Updated))
                _consistentHash.StoreItem(node.EndPoint.ToString());
        }
Ejemplo n.º 2
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        public void MoveObjectCallBack(object state)
        {
            Node targetNode = (Node)state;
            string nodeKeyHash = Hasher.GetHash(targetNode.EndPoint.ToString());
            string previousNodeHash = Hasher.GetHash(_nodeResolver.GetPreviousItemInCircle(targetNode.EndPoint.ToString()));

            //if self is B, typical scenarios -> A-newnode-MID-B, MID-A-newnode-B-C
            //A being the previous node, B being the current node and newnode being the new node.
            string lowerBound = previousNodeHash;
            string upperBound = nodeKeyHash;
            IEnumerable<KeyValuePair<string, ServerCacheItem>> candidateList = _cache.Where<KeyValuePair<string, ServerCacheItem>>(x =>
                ((x.Value.Hash.CompareTo(upperBound) < 0) &&
                (x.Value.Hash.CompareTo(lowerBound) > 0)));

            //special case: A-MID-newnode-B
            if (lowerBound.CompareTo(upperBound) > 0)
            {
                candidateList = _cache.Where<KeyValuePair<string, ServerCacheItem>>(x =>
                ((x.Value.Hash.CompareTo(upperBound) < 0) ||
                (x.Value.Hash.CompareTo(lowerBound) > 0)));
            }

            if (candidateList.Count() == 0)
                return;

            Node self = new Node() { EndPoint = TcpHelper.SelfIPAddress, NodeState= NodeState.Active};

            //prepare the connection
            string endPoint = string.Format("net.tcp://{0}:{1}/HoCCacheService", targetNode.EndPoint.ToString(), targetNode.ServicePort);
            CacheServiceReference.CacheServiceClient nodeService = new CacheServiceReference.CacheServiceClient(new NetTcpBinding(SecurityMode.None), new EndpointAddress(endPoint));
            try
            {
                //move each of the object to the other node async
                foreach (KeyValuePair<string, ServerCacheItem> valuePair in candidateList)
                {
                    nodeService.DoInterNodeObjectTransfer(self, valuePair.Key, valuePair.Value);
                    valuePair.Value.ItemState = CacheItemState.Moved;
                    valuePair.Value.RelocatedTo = targetNode;
                };
                nodeService.EndInterNodeObjectTransfer(self);

                Thread.Sleep(2000);//wait the current thread - note that this is not the main thread
                RemoveOrResetMovedItems(targetNode);

                //note that any object update that happens during this time is handled by the CacheService.
                //basically it copies the update to the new node too.
            }
            catch
            {
                ResetMovedObjectState(); //in case of any issues revert back to normal state.
            }
        }
Ejemplo n.º 3
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        public bool DoInterNodeObjectTransfer(Node sourceNode, string key, ServerCacheItem cacheItem)
        {
            //note that DoInterNodeObjectTransfer could be called during a shutdown of the sourceNode too
            //the below case happens only when this current node comes online
            if (NodeState == Common.NodeState.WaitingForNeighbourNode)
            {
                NodeState = NodeState.ReceivingFromOtherNode;
                heartBeatResetter.Change(6000, Timeout.Infinite); //keep resetting the timer
            }

            Func<string, ServerCacheItem, ServerCacheItem> updateValueFactory = ((x, y) => (cacheItem));
            _localCache.AddOrUpdate(key, cacheItem, updateValueFactory);
            return true;
        }
Ejemplo n.º 4
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        public void StoreCacheItem(string key, ClientCacheItem value)
        {
            ServerCacheItem cacheItemWrapped;
            if (!_localCache.TryGetValue(key, out cacheItemWrapped))
                cacheItemWrapped = new ServerCacheItem() { ItemState = CacheItemState.None };

            cacheItemWrapped.Hash = Hasher.GetHash(key);
            cacheItemWrapped.Value = value;

            Func<string, ServerCacheItem, ServerCacheItem> updateValueFactory = ((x, y) => (cacheItemWrapped));
            _localCache.AddOrUpdate(key, cacheItemWrapped, updateValueFactory);

            //has the item been moved to another node?
            if (cacheItemWrapped.ItemState == CacheItemState.Moved)
            {
                Debug.Assert(cacheItemWrapped.RelocatedTo != null);
                Node self = new Node() { EndPoint = TcpHelper.SelfIPAddress, NodeState = NodeState.Active };

                //prepare the connection
                string endPoint = string.Format("net.tcp://{0}:{1}/HoCCacheService", cacheItemWrapped.RelocatedTo.EndPoint.ToString(), cacheItemWrapped.RelocatedTo.ServicePort);
                CacheServiceReference.CacheServiceClient nodeService = new CacheServiceReference.CacheServiceClient(new NetTcpBinding(SecurityMode.None), new EndpointAddress(endPoint));

                //update to the target node.
                nodeService.StoreCacheItem(key, value);
            }
        }
Ejemplo n.º 5
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        public bool EndInterNodeObjectTransfer(Node sourceNode)
        {
            NodeState = NodeState.Active; //get online
            _heartBeat.SendBeat();//force a beat now

            heartBeatResetter.Change(0, Timeout.Infinite);//dont want the timer to fire henceforth
            return true;
        }
Ejemplo n.º 6
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        private void RemoveOrResetMovedItems(Node targetNode)
        {
            Func<Node, bool> nodeCompare = x => (x.EndPoint.ToString().CompareTo(targetNode.EndPoint.ToString()) == 0);
            Node targetNodeInternal = _nodeTracker.ActiveNodes.First<Node>(nodeCompare);

            if (targetNodeInternal == null)
                ResetMovedObjectState();
            else if (targetNodeInternal.NodeState == NodeState.Active) //is the target node now active?
                RemoveMovedObjectState();
            else
                ResetMovedObjectState(); // reset all moved states as the node does not appear to have got online yet
        }
Ejemplo n.º 7
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        private void NodeListUpdated(Node node, NodeUpdateAction updateAction)
        {
            //has the node just come online and waiting for its data that I have?
            if ((updateAction == NodeUpdateAction.Added) && (node.NodeState == NodeState.WaitingForNeighbourNode))
            {
                //was that node me?
                if (node.EndPoint.ToString().CompareTo(TcpHelper.SelfIPAddress.ToString()) == 0)
                    return;

                bool nodeIsNeighbourBehind = NodeIsNeighbourBehind(node);

                if (!nodeIsNeighbourBehind)
                    return;

                ThreadPool.QueueUserWorkItem(MoveObjectCallBack, node);
            }
        }
Ejemplo n.º 8
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        private bool NodeIsNeighbourBehind(Node node)
        {
            //add the new node to a temporary clone of the active consistent hash
            ConsistentHash consistentHashTrialRun = _nodeResolver.GetActiveConsistentHashClone();
            consistentHashTrialRun.StoreItem(node.EndPoint.ToString());

            //ask the consistent hash that if the node was around, would that node be my immediate previous neighbour?
            string previousItem = consistentHashTrialRun.GetPreviousItemInCircle(TcpHelper.SelfIPAddress.ToString());
            if (node.EndPoint.ToString().CompareTo(previousItem) == 0)
                return true;

            return false;
        }
Ejemplo n.º 9
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        public void PerformShutdownMove()
        {
            //targetnode is the one which comes next in the circle, effectively returned by GetObjectLocation
            Node targetNode = _nodeResolver.GetObjectLocation(TcpHelper.SelfIPAddress.ToString());

            //is targetnode self? (am I the only node in the circle?)
            if (targetNode.EndPoint.ToString().CompareTo(TcpHelper.SelfIPAddress.ToString()) == 0)
                return;

            string endPoint = string.Format("net.tcp://{0}:{1}/HoCCacheService", targetNode.EndPoint.ToString(), targetNode.ServicePort);
            CacheServiceReference.CacheServiceClient nodeService = new CacheServiceReference.CacheServiceClient(new NetTcpBinding(SecurityMode.None), new EndpointAddress(endPoint));

            Node self = new Node() { EndPoint = TcpHelper.SelfIPAddress, NodeState= NodeState.Active};

            //move the objects to the nearest node async
            Parallel.ForEach<KeyValuePair<string, ServerCacheItem>>(_cache, valuePair =>
            {
                nodeService.DoInterNodeObjectTransfer(self, valuePair.Key, valuePair.Value);
                valuePair.Value.ItemState = CacheItemState.Moved;
                valuePair.Value.RelocatedTo = targetNode;
            });
        }
Ejemplo n.º 10
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        private void HeartBeatTracker(HeartBeatData heartBeatData)
        {
            IPAddress nodeIPAddress = new IPAddress(heartBeatData.IPAddress);
            Node node = _activeNodes.Find(x => x.EndPoint.ToString() == nodeIPAddress.ToString());

            NodeUpdateAction updateAction;

            if (node != null)
            {
                //update the last heard time, node state
                node.HeartBeatLastHeardAt = DateTime.Now;
                node.NodeState = heartBeatData.NodeState;
                node.EndPoint = nodeIPAddress;
                node.ServicePort = heartBeatData.ServicePort;

                updateAction = NodeUpdateAction.Updated;
            }
            else
            {
                node = new Node()
                {
                    EndPoint = nodeIPAddress,
                    ServicePort = heartBeatData.ServicePort,
                    HeartBeatLastHeardAt = DateTime.Now,
                    NodeState = heartBeatData.NodeState
                };

                lock (_activeNodes)
                {
                    _activeNodes.Add(node); //add the new node which appears to have just come online.
                }

                updateAction = NodeUpdateAction.Added;
            }

            if (OnNodeListUpdated != null)
                OnNodeListUpdated(node, updateAction);
        }
Ejemplo n.º 11
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        private void NodeListUpdated(Node node, NodeUpdateAction updateAction)
        {
            if (updateAction == NodeUpdateAction.Added)
            {
                Dispatcher.Invoke((Action)(() => {
                    tvNodes.Items.Add(node.EndPoint.ToString());
                    if (tvNodes.Items.Count == 1)
                    {
                        SetSelectedItem(tvNodes, tvNodes.Items[0]);
                    }

                    UpdateStatusMessage("Discovered new node " + node.EndPoint.ToString());
                }));
            }
            else if (updateAction == NodeUpdateAction.Removed)
            {
                Dispatcher.Invoke((Action)(() => {
                    tvNodes.Items.Remove(node.EndPoint.ToString());
                    UpdateStatusMessage("Removed dead node " + node.EndPoint.ToString());
                    ClearGrid();
                }));
            }
        }