LibUv Networking (#65)

Projects/Server/ApplicationLifetime.cs

@@ -0,0 +1,108 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Hosting
+{
+  /// <summary>
+  /// Allows consumers to perform cleanup during a graceful shutdown.
+  /// </summary>
+  internal class ApplicationLifetime : IHostApplicationLifetime
+  {
+    private readonly CancellationTokenSource _startedSource = new CancellationTokenSource();
+    private readonly CancellationTokenSource _stoppingSource = new CancellationTokenSource();
+    private readonly CancellationTokenSource _stoppedSource = new CancellationTokenSource();
+    private readonly ILogger<ApplicationLifetime> _logger;
+
+    public ApplicationLifetime(ILogger<ApplicationLifetime> logger) => _logger = logger;
+
+    /// <summary>
+    /// Triggered when the application host has fully started and is about to wait
+    /// for a graceful shutdown.
+    /// </summary>
+    public CancellationToken ApplicationStarted => _startedSource.Token;
+
+    /// <summary>
+    /// Triggered when the application host is performing a graceful shutdown.
+    /// Request may still be in flight. Shutdown will block until this event completes.
+    /// </summary>
+    public CancellationToken ApplicationStopping => _stoppingSource.Token;
+
+    /// <summary>
+    /// Triggered when the application host is performing a graceful shutdown.
+    /// All requests should be complete at this point. Shutdown will block
+    /// until this event completes.
+    /// </summary>
+    public CancellationToken ApplicationStopped => _stoppedSource.Token;
+
+    /// <summary>
+    /// Signals the ApplicationStopping event and blocks until it completes.
+    /// </summary>
+    public void StopApplication()
+    {
+      // Lock on CTS to synchronize multiple calls to StopApplication. This guarantees that the first call
+      // to StopApplication and its callbacks run to completion before subsequent calls to StopApplication,
+      // which will no-op since the first call already requested cancellation, get a chance to execute.
+      lock (_stoppingSource)
+      {
+        try
+        {
+          ExecuteHandlers(_stoppingSource);
+        }
+        catch (Exception)
+        {
+          /*                    _logger.ApplicationError(LoggerEventIds.ApplicationStoppingException,
+                                                       "An error occurred stopping the application",
+                                                       ex);*/
+        }
+      }
+    }
+
+    /// <summary>
+    /// Signals the ApplicationStarted event and blocks until it completes.
+    /// </summary>
+    public void NotifyStarted()
+    {
+      try
+      {
+        ExecuteHandlers(_startedSource);
+      }
+      catch (Exception)
+      {
+        /*                _logger.ApplicationError(LoggerEventIds.ApplicationStartupException,
+                                                 "An error occurred starting the application",
+                                                 ex);*/
+      }
+    }
+
+    /// <summary>
+    /// Signals the ApplicationStopped event and blocks until it completes.
+    /// </summary>
+    public void NotifyStopped()
+    {
+      try
+      {
+        ExecuteHandlers(_stoppedSource);
+      }
+      catch (Exception)
+      {
+        /*                _logger.ApplicationError(LoggerEventIds.ApplicationStoppedException,
+                                                 "An error occurred stopping the application",
+                                                 ex);*/
+      }
+    }
+
+    private void ExecuteHandlers(CancellationTokenSource cancel)
+    {
+      // Noop if this is already cancelled
+      if (cancel.IsCancellationRequested) return;
+
+      // Run the cancellation token callbacks
+      cancel.Cancel(false);
+    }
+  }
+}