/// <summary>
/// The middleware used for forwarding incoming hub messages to other servers.
/// </summary>
/// <param name="config">DotNetify configuration.</param>
/// <param name="serverUrls">Array of URLs of the servers to forward messages to.</param>
/// <param name="haltPipeline">Whether to prevent further processing in this server after forwarding messages.</param>
public static IDotNetifyConfiguration UseForwarding(this IDotNetifyConfiguration config, string[] serverUrls, Action <ForwardingOptions> optionsAccessor = null)
{
for (int i = 0; i < serverUrls.Length; i++)
{
var forwardingOptions = new ForwardingOptions();
optionsAccessor?.Invoke(forwardingOptions);
if (i < serverUrls.Length - 1)
{
forwardingOptions.HaltPipeline = false;
}
config.UseMiddleware <ForwardingMiddleware>(serverUrls[i], forwardingOptions);
}
return(config);
}
private DotNetifyHubForwarder CreateInstance(string serverUrl, ForwardingOptions config)
{
var hubProxy = _hubProxyFactory.GetInstance();
if (config.UseMessagePack)
{
(hubProxy as DotNetifyHubProxy).ConnectionBuilder = builder => builder.AddMessagePackProtocol();
}
else
{
(hubProxy as DotNetifyHubProxy).ConnectionBuilder = builder => builder.AddJsonProtocol();
}
hubProxy.Init(null, serverUrl);
return(new DotNetifyHubForwarder(hubProxy, new DotNetifyHubResponse(_globalHubContext)));
}
public async Task InvokeInstanceAsync(string serverUrl, ForwardingOptions config, Func <DotNetifyHubForwarder, Task> invoke)
{
var pool = GetConnectionPool(serverUrl, config);
var hubForwarder = await pool.TakeAsync();
var semaphore = _semaphores.GetOrAdd(hubForwarder, _ => new SemaphoreSlim(1));
await semaphore.WaitAsync();
await hubForwarder.StartAsync();
try
{
await invoke(hubForwarder);
}
catch (Exception ex)
{
throw new ForwardingException(ex.Message, ex);
}
finally
{
semaphore.Release();
_ = pool.AddAsync(hubForwarder);
}
}
/// <summary>
/// Class constructor.
/// </summary>
/// <param name="hubForwarderFactory">Factory of hub message forwarder objects.</param>
/// <param name="serverUrl">URL of the server to forward messages to.</param>
/// <param name="config">Forwarding configuration.</param>
public ForwardingMiddleware(IDotNetifyHubForwarderFactory hubForwarderFactory, string serverUrl, ForwardingOptions config)
{
_hubForwarderFactory = hubForwarderFactory;
_serverUrl = serverUrl;
_config = config;
}
private AsyncCollection <DotNetifyHubForwarder> GetConnectionPool(string serverUrl, ForwardingOptions config)
{
return(_hubForwarders.GetOrAdd(serverUrl, url =>
{
var newForwarders = Enumerable.Range(1, config.ConnectionPoolSize).Select(x => CreateInstance(serverUrl, config));
return new AsyncCollection <DotNetifyHubForwarder>(new ConcurrentQueue <DotNetifyHubForwarder>(newForwarders));
}));
}