Merge remote-tracking branch 'upstream/master' into api-upload-subtitle

1 files changed, 269 insertions, 23 deletions

diff --git a/Emby.Server.Implementations/Session/SessionWebSocketListener.cs b/Emby.Server.Implementations/Session/SessionWebSocketListener.cs
index 930f2d35d..15c2af220 100644
--- a/Emby.Server.Implementations/Session/SessionWebSocketListener.cs
+++ b/Emby.Server.Implementations/Session/SessionWebSocketListener.cs
@@ -1,64 +1,103 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.WebSockets;
+using System.Threading;
 using System.Threading.Tasks;
+using Jellyfin.Data.Events;
 using MediaBrowser.Controller.Net;
 using MediaBrowser.Controller.Session;
-using MediaBrowser.Model.Events;
-using MediaBrowser.Model.Serialization;
+using MediaBrowser.Model.Net;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 
 namespace Emby.Server.Implementations.Session
 {
     /// <summary>
-    /// Class SessionWebSocketListener
+    /// Class SessionWebSocketListener.
     /// </summary>
-    public class SessionWebSocketListener : IWebSocketListener, IDisposable
+    public sealed class SessionWebSocketListener : IWebSocketListener, IDisposable
     {
         /// <summary>
-        /// The _session manager
+        /// 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;
 
         /// <summary>
-        /// The _logger
+        /// The _logger.
         /// </summary>
-        private readonly ILogger _logger;
+        private readonly ILogger<SessionWebSocketListener> _logger;
+        private readonly ILoggerFactory _loggerFactory;
+
+        private readonly IWebSocketManager _webSocketManager;
 
         /// <summary>
-        /// The _dto service
+        /// The KeepAlive cancellation token.
         /// </summary>
-        private readonly IJsonSerializer _json;
+        private CancellationTokenSource _keepAliveCancellationToken;
 
-        private readonly IHttpServer _httpServer;
+        /// <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>
         /// <param name="sessionManager">The session manager.</param>
         /// <param name="loggerFactory">The logger factory.</param>
-        /// <param name="json">The json.</param>
-        /// <param name="httpServer">The HTTP server.</param>
-        public SessionWebSocketListener(ISessionManager sessionManager, ILoggerFactory loggerFactory, IJsonSerializer json, IHttpServer httpServer)
+        /// <param name="webSocketManager">The HTTP server.</param>
+        public SessionWebSocketListener(
+            ILogger<SessionWebSocketListener> logger,
+            ISessionManager sessionManager,
+            ILoggerFactory loggerFactory,
+            IWebSocketManager webSocketManager)
         {
+            _logger = logger;
             _sessionManager = sessionManager;
-            _logger = loggerFactory.CreateLogger(GetType().Name);
-            _json = json;
-            _httpServer = httpServer;
-            httpServer.WebSocketConnected += _serverManager_WebSocketConnected;
+            _loggerFactory = loggerFactory;
+            _webSocketManager = webSocketManager;
+
+            webSocketManager.WebSocketConnected += OnServerManagerWebSocketConnected;
         }
 
-        void _serverManager_WebSocketConnected(object sender, GenericEventArgs<IWebSocketConnection> e)
+        private async void OnServerManagerWebSocketConnected(object sender, GenericEventArgs<IWebSocketConnection> e)
         {
-            var session = GetSession(e.Argument.QueryString, e.Argument.RemoteEndPoint);
-
+            var session = GetSession(e.Argument.QueryString, e.Argument.RemoteEndPoint.ToString());
             if (session != null)
             {
                 EnsureController(session, e.Argument);
+                await KeepAliveWebSocket(e.Argument).ConfigureAwait(false);
             }
             else
             {
-                _logger.LogWarning("Unable to determine session based on url: {0}", e.Argument.Url);
+                _logger.LogWarning("Unable to determine session based on query string: {0}", e.Argument.QueryString);
             }
         }
 
@@ -79,9 +118,11 @@ namespace Emby.Server.Implementations.Session
             return _sessionManager.GetSessionByAuthenticationToken(token, deviceId, remoteEndpoint);
         }
 
+        /// <inheritdoc />
         public void Dispose()
         {
-            _httpServer.WebSocketConnected -= _serverManager_WebSocketConnected;
+            _webSocketManager.WebSocketConnected -= OnServerManagerWebSocketConnected;
+            StopKeepAlive();
         }
 
         /// <summary>
@@ -94,10 +135,215 @@ namespace Emby.Server.Implementations.Session
 
         private void EnsureController(SessionInfo session, IWebSocketConnection connection)
         {
-            var controllerInfo = session.EnsureController<WebSocketController>(s => new WebSocketController(s, _logger, _sessionManager));
+            var controllerInfo = session.EnsureController<WebSocketController>(
+                s => new WebSocketController(_loggerFactory.CreateLogger<WebSocketController>(), s, _sessionManager));
 
             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).ConfigureAwait(false);
+            }
+            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.Dispose();
+                    _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.Count > 0)
+            {
+                _logger.LogInformation("Sending ForceKeepAlive message to {0} inactive WebSockets.", inactive.Count);
+            }
+
+            foreach (var webSocket in inactive)
+            {
+                try
+                {
+                    await SendForceKeepAlive(webSocket).ConfigureAwait(false);
+                }
+                catch (WebSocketException exception)
+                {
+                    _logger.LogInformation(exception, "Error sending ForceKeepAlive message to WebSocket.");
+                    lost.Add(webSocket);
+                }
+            }
+
+            lock (_webSocketsLock)
+            {
+                if (lost.Count > 0)
+                {
+                    _logger.LogInformation("Lost {0} WebSockets.", lost.Count);
+                    foreach (var webSocket in lost)
+                    {
+                        // TODO: handle session relative to the lost webSocket
+                        RemoveWebSocket(webSocket);
+                    }
+                }
+
+                if (_webSockets.Count == 0)
+                {
+                    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().ConfigureAwait(false);
+
+                try
+                {
+                    await Task.Delay(interval, cancellationToken).ConfigureAwait(false);
+                }
+                catch (TaskCanceledException)
+                {
+                    return;
+                }
+            }
+        }
     }
 }