diff options
Diffstat (limited to 'Emby.Server.Implementations/Session/SessionWebSocketListener.cs')
| -rw-r--r-- | Emby.Server.Implementations/Session/SessionWebSocketListener.cs | 245 |
1 files changed, 244 insertions, 1 deletions
diff --git a/Emby.Server.Implementations/Session/SessionWebSocketListener.cs b/Emby.Server.Implementations/Session/SessionWebSocketListener.cs index d4e4ba1f2..e7b4b0ec3 100644 --- a/Emby.Server.Implementations/Session/SessionWebSocketListener.cs +++ b/Emby.Server.Implementations/Session/SessionWebSocketListener.cs @@ -1,8 +1,13 @@ using System; +using System.Collections.Generic; +using System.Linq; +using System.Net.WebSockets; +using System.Threading; using System.Threading.Tasks; using MediaBrowser.Controller.Net; using MediaBrowser.Controller.Session; using MediaBrowser.Model.Events; +using MediaBrowser.Model.Net; using Microsoft.AspNetCore.Http; using Microsoft.Extensions.Logging; @@ -14,6 +19,21 @@ namespace Emby.Server.Implementations.Session public sealed class SessionWebSocketListener : IWebSocketListener, IDisposable { /// <summary> + /// The timeout in seconds after which a WebSocket is considered to be lost. + /// </summary> + public const int WebSocketLostTimeout = 60; + + /// <summary> + /// The keep-alive interval factor; controls how often the watcher will check on the status of the WebSockets. + /// </summary> + public const float IntervalFactor = 0.2f; + + /// <summary> + /// The ForceKeepAlive factor; controls when a ForceKeepAlive is sent. + /// </summary> + public const float ForceKeepAliveFactor = 0.75f; + + /// <summary> /// The _session manager /// </summary> private readonly ISessionManager _sessionManager; @@ -27,6 +47,26 @@ namespace Emby.Server.Implementations.Session private readonly IHttpServer _httpServer; /// <summary> + /// The KeepAlive cancellation token. + /// </summary> + private CancellationTokenSource _keepAliveCancellationToken; + + /// <summary> + /// Lock used for accesing the KeepAlive cancellation token. + /// </summary> + private readonly object _keepAliveLock = new object(); + + /// <summary> + /// The WebSocket watchlist. + /// </summary> + private readonly HashSet<IWebSocketConnection> _webSockets = new HashSet<IWebSocketConnection>(); + + /// <summary> + /// Lock used for accesing the WebSockets watchlist. + /// </summary> + private readonly object _webSocketsLock = new object(); + + /// <summary> /// Initializes a new instance of the <see cref="SessionWebSocketListener" /> class. /// </summary> /// <param name="logger">The logger.</param> @@ -47,12 +87,13 @@ namespace Emby.Server.Implementations.Session httpServer.WebSocketConnected += OnServerManagerWebSocketConnected; } - private void OnServerManagerWebSocketConnected(object sender, GenericEventArgs<IWebSocketConnection> e) + private async void OnServerManagerWebSocketConnected(object sender, GenericEventArgs<IWebSocketConnection> e) { var session = GetSession(e.Argument.QueryString, e.Argument.RemoteEndPoint.ToString()); if (session != null) { EnsureController(session, e.Argument); + await KeepAliveWebSocket(e.Argument); } else { @@ -81,6 +122,7 @@ namespace Emby.Server.Implementations.Session public void Dispose() { _httpServer.WebSocketConnected -= OnServerManagerWebSocketConnected; + StopKeepAlive(); } /// <summary> @@ -99,5 +141,206 @@ namespace Emby.Server.Implementations.Session var controller = (WebSocketController)controllerInfo.Item1; controller.AddWebSocket(connection); } + + /// <summary> + /// Called when a WebSocket is closed. + /// </summary> + /// <param name="sender">The WebSocket.</param> + /// <param name="e">The event arguments.</param> + private void OnWebSocketClosed(object sender, EventArgs e) + { + var webSocket = (IWebSocketConnection)sender; + _logger.LogDebug("WebSocket {0} is closed.", webSocket); + RemoveWebSocket(webSocket); + } + + /// <summary> + /// Adds a WebSocket to the KeepAlive watchlist. + /// </summary> + /// <param name="webSocket">The WebSocket to monitor.</param> + private async Task KeepAliveWebSocket(IWebSocketConnection webSocket) + { + lock (_webSocketsLock) + { + if (!_webSockets.Add(webSocket)) + { + _logger.LogWarning("Multiple attempts to keep alive single WebSocket {0}", webSocket); + return; + } + webSocket.Closed += OnWebSocketClosed; + webSocket.LastKeepAliveDate = DateTime.UtcNow; + + StartKeepAlive(); + } + + // Notify WebSocket about timeout + try + { + await SendForceKeepAlive(webSocket); + } + catch (WebSocketException exception) + { + _logger.LogWarning(exception, "Cannot send ForceKeepAlive message to WebSocket {0}.", webSocket); + } + } + + /// <summary> + /// Removes a WebSocket from the KeepAlive watchlist. + /// </summary> + /// <param name="webSocket">The WebSocket to remove.</param> + private void RemoveWebSocket(IWebSocketConnection webSocket) + { + lock (_webSocketsLock) + { + if (!_webSockets.Remove(webSocket)) + { + _logger.LogWarning("WebSocket {0} not on watchlist.", webSocket); + } + else + { + webSocket.Closed -= OnWebSocketClosed; + } + } + } + + /// <summary> + /// Starts the KeepAlive watcher. + /// </summary> + private void StartKeepAlive() + { + lock (_keepAliveLock) + { + if (_keepAliveCancellationToken == null) + { + _keepAliveCancellationToken = new CancellationTokenSource(); + // Start KeepAlive watcher + _ = RepeatAsyncCallbackEvery( + KeepAliveSockets, + TimeSpan.FromSeconds(WebSocketLostTimeout * IntervalFactor), + _keepAliveCancellationToken.Token); + } + } + } + + /// <summary> + /// Stops the KeepAlive watcher. + /// </summary> + private void StopKeepAlive() + { + lock (_keepAliveLock) + { + if (_keepAliveCancellationToken != null) + { + _keepAliveCancellationToken.Cancel(); + _keepAliveCancellationToken = null; + } + } + + lock (_webSocketsLock) + { + foreach (var webSocket in _webSockets) + { + webSocket.Closed -= OnWebSocketClosed; + } + + _webSockets.Clear(); + } + } + + /// <summary> + /// Checks status of KeepAlive of WebSockets. + /// </summary> + private async Task KeepAliveSockets() + { + List<IWebSocketConnection> inactive; + List<IWebSocketConnection> lost; + + lock (_webSocketsLock) + { + _logger.LogDebug("Watching {0} WebSockets.", _webSockets.Count); + + inactive = _webSockets.Where(i => + { + var elapsed = (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds; + return (elapsed > WebSocketLostTimeout * ForceKeepAliveFactor) && (elapsed < WebSocketLostTimeout); + }).ToList(); + lost = _webSockets.Where(i => (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds >= WebSocketLostTimeout).ToList(); + } + + if (inactive.Any()) + { + _logger.LogInformation("Sending ForceKeepAlive message to {0} inactive WebSockets.", inactive.Count); + } + + foreach (var webSocket in inactive) + { + try + { + await SendForceKeepAlive(webSocket); + } + catch (WebSocketException exception) + { + _logger.LogInformation(exception, "Error sending ForceKeepAlive message to WebSocket."); + lost.Add(webSocket); + } + } + + lock (_webSocketsLock) + { + if (lost.Any()) + { + _logger.LogInformation("Lost {0} WebSockets.", lost.Count); + foreach (var webSocket in lost) + { + // TODO: handle session relative to the lost webSocket + RemoveWebSocket(webSocket); + } + } + + if (!_webSockets.Any()) + { + StopKeepAlive(); + } + } + } + + /// <summary> + /// Sends a ForceKeepAlive message to a WebSocket. + /// </summary> + /// <param name="webSocket">The WebSocket.</param> + /// <returns>Task.</returns> + private Task SendForceKeepAlive(IWebSocketConnection webSocket) + { + return webSocket.SendAsync(new WebSocketMessage<int> + { + MessageType = "ForceKeepAlive", + Data = WebSocketLostTimeout + }, CancellationToken.None); + } + + /// <summary> + /// Runs a given async callback once every specified interval time, until cancelled. + /// </summary> + /// <param name="callback">The async callback.</param> + /// <param name="interval">The interval time.</param> + /// <param name="cancellationToken">The cancellation token.</param> + /// <returns>Task.</returns> + private async Task RepeatAsyncCallbackEvery(Func<Task> callback, TimeSpan interval, CancellationToken cancellationToken) + { + while (!cancellationToken.IsCancellationRequested) + { + await callback(); + Task task = Task.Delay(interval, cancellationToken); + + try + { + await task; + } + catch (TaskCanceledException) + { + return; + } + } + } } } |