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using MediaBrowser.Common.Logging;
using MediaBrowser.Common.Net;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Model.Logging;
namespace MediaBrowser.Common.Kernel
{
/// <summary>
/// Starts sending data over a web socket periodically when a message is received, and then stops when a corresponding stop message is received
/// </summary>
/// <typeparam name="TKernelType">The type of the T kernel type.</typeparam>
/// <typeparam name="TReturnDataType">The type of the T return data type.</typeparam>
/// <typeparam name="TStateType">The type of the T state type.</typeparam>
public abstract class BasePeriodicWebSocketListener<TKernelType, TReturnDataType, TStateType> : BaseWebSocketListener<TKernelType>
where TKernelType : IKernel
where TStateType : class, new()
{
/// <summary>
/// The _active connections
/// </summary>
protected readonly List<Tuple<WebSocketConnection, CancellationTokenSource, Timer, TStateType, SemaphoreSlim>> ActiveConnections =
new List<Tuple<WebSocketConnection, CancellationTokenSource, Timer, TStateType, SemaphoreSlim>>();
/// <summary>
/// Gets the name.
/// </summary>
/// <value>The name.</value>
protected abstract string Name { get; }
/// <summary>
/// Gets the data to send.
/// </summary>
/// <param name="state">The state.</param>
/// <returns>Task{`1}.</returns>
protected abstract Task<TReturnDataType> GetDataToSend(TStateType state);
/// <summary>
/// The logger
/// </summary>
protected ILogger Logger;
/// <summary>
/// Initializes a new instance of the <see cref="BasePeriodicWebSocketListener{TStateType}" /> class.
/// </summary>
/// <param name="logger">The logger.</param>
protected BasePeriodicWebSocketListener(ILogger logger)
{
if (logger == null)
{
throw new ArgumentNullException("logger");
}
Logger = logger;
}
/// <summary>
/// Processes the message internal.
/// </summary>
/// <param name="message">The message.</param>
/// <returns>Task.</returns>
protected override Task ProcessMessageInternal(WebSocketMessageInfo message)
{
if (message.MessageType.Equals(Name + "Start", StringComparison.OrdinalIgnoreCase))
{
Start(message);
}
if (message.MessageType.Equals(Name + "Stop", StringComparison.OrdinalIgnoreCase))
{
Stop(message);
}
return NullTaskResult;
}
/// <summary>
/// Starts sending messages over a web socket
/// </summary>
/// <param name="message">The message.</param>
private void Start(WebSocketMessageInfo message)
{
var vals = message.Data.Split(',');
var dueTimeMs = long.Parse(vals[0]);
var periodMs = long.Parse(vals[1]);
var cancellationTokenSource = new CancellationTokenSource();
Logger.Info("{1} Begin transmitting over websocket to {0}", message.Connection.RemoteEndPoint, GetType().Name);
var timer = new Timer(TimerCallback, message.Connection, Timeout.Infinite, Timeout.Infinite);
var state = new TStateType();
var semaphore = new SemaphoreSlim(1, 1);
lock (ActiveConnections)
{
ActiveConnections.Add(new Tuple<WebSocketConnection, CancellationTokenSource, Timer, TStateType, SemaphoreSlim>(message.Connection, cancellationTokenSource, timer, state, semaphore));
}
timer.Change(TimeSpan.FromMilliseconds(dueTimeMs), TimeSpan.FromMilliseconds(periodMs));
}
/// <summary>
/// Timers the callback.
/// </summary>
/// <param name="state">The state.</param>
private async void TimerCallback(object state)
{
var connection = (WebSocketConnection)state;
Tuple<WebSocketConnection, CancellationTokenSource, Timer, TStateType, SemaphoreSlim> tuple;
lock (ActiveConnections)
{
tuple = ActiveConnections.FirstOrDefault(c => c.Item1 == connection);
}
if (tuple == null)
{
return;
}
if (connection.State != WebSocketState.Open || tuple.Item2.IsCancellationRequested)
{
DisposeConnection(tuple);
return;
}
try
{
await tuple.Item5.WaitAsync(tuple.Item2.Token).ConfigureAwait(false);
var data = await GetDataToSend(tuple.Item4).ConfigureAwait(false);
await connection.SendAsync(new WebSocketMessage<TReturnDataType>
{
MessageType = Name,
Data = data
}, tuple.Item2.Token).ConfigureAwait(false);
}
catch (OperationCanceledException)
{
if (tuple.Item2.IsCancellationRequested)
{
DisposeConnection(tuple);
}
}
catch (Exception ex)
{
Logger.ErrorException("Error sending web socket message {0}", ex, Name);
DisposeConnection(tuple);
}
finally
{
tuple.Item5.Release();
}
}
/// <summary>
/// Stops sending messages over a web socket
/// </summary>
/// <param name="message">The message.</param>
private void Stop(WebSocketMessageInfo message)
{
lock (ActiveConnections)
{
var connection = ActiveConnections.FirstOrDefault(c => c.Item1 == message.Connection);
if (connection != null)
{
DisposeConnection(connection);
}
}
}
/// <summary>
/// Disposes the connection.
/// </summary>
/// <param name="connection">The connection.</param>
private void DisposeConnection(Tuple<WebSocketConnection, CancellationTokenSource, Timer, TStateType, SemaphoreSlim> connection)
{
Logger.Info("{1} stop transmitting over websocket to {0}", connection.Item1.RemoteEndPoint, GetType().Name);
try
{
connection.Item3.Dispose();
}
catch (ObjectDisposedException)
{
}
try
{
connection.Item2.Cancel();
connection.Item2.Dispose();
}
catch (ObjectDisposedException)
{
}
try
{
connection.Item5.Dispose();
}
catch (ObjectDisposedException)
{
}
ActiveConnections.Remove(connection);
}
/// <summary>
/// Releases unmanaged and - optionally - managed resources.
/// </summary>
/// <param name="dispose"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
protected override void Dispose(bool dispose)
{
if (dispose)
{
lock (ActiveConnections)
{
foreach (var connection in ActiveConnections.ToList())
{
DisposeConnection(connection);
}
}
}
base.Dispose(dispose);
}
}
}
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