/// <summary>
/// Gets a client from the pool if one is available, otherwise creates one.
/// </summary>
/// <remarks>If capacity is reached, an exception is raised.</remarks>
public ScadaClient GetClient(ConnectionOptions connectionOptions)
{
if (connectionOptions == null)
{
throw new ArgumentNullException(nameof(connectionOptions));
}
string optionsKey = GetOptionsKey(connectionOptions);
ClientGroup clientGroup;
lock (clientGroups)
{
if (!clientGroups.TryGetValue(optionsKey, out clientGroup))
{
clientGroup = new ClientGroup(connectionOptions, Capacity, ClientMode);
clientGroups.Add(optionsKey, clientGroup);
}
}
DateTime utcNow = DateTime.UtcNow;
ScadaClient scadaClient = clientGroup.GetClient(utcNow);
// cleanup the pool
if (utcNow - lastCleanupTime > CleanupPeriod)
{
RemoveOutdatedClients(utcNow);
}
return(scadaClient);
}
/// <summary>
/// Removes and returns the client at the end of the client list.
/// </summary>
private ScadaClient PopClient()
{
int lastIndex = availableClients.Count - 1;
ScadaClient scadaClient = availableClients[lastIndex];
availableClients.RemoveAt(lastIndex);
return(scadaClient);
}
/// <summary>
/// Returns the client to the group.
/// </summary>
public void ReturnClient(ScadaClient client, DateTime nowDT)
{
lock (this)
{
LastAccessTime = nowDT;
if (usedClients.Remove(client.ClientID))
{
availableClients.Add(client);
}
}
}
/// <summary>
/// Gets a client from the group if one is available, otherwise creates one.
/// </summary>
public ScadaClient GetClient(DateTime nowDT)
{
lock (this)
{
LastAccessTime = nowDT;
ScadaClient scadaClient = availableClients.Count > 0
? PopClient()
: CreateClient();
usedClients[scadaClient.ClientID] = scadaClient;
return(scadaClient);
}
}
/// <summary>
/// Returns the client to the pool.
/// </summary>
public void ReturnClient(ScadaClient client)
{
if (client != null)
{
ClientGroup clientGroup;
lock (clientGroups)
{
clientGroups.TryGetValue(GetOptionsKey(client.ConnectionOptions), out clientGroup);
}
clientGroup?.ReturnClient(client, DateTime.UtcNow);
}
}