netcore/System.Private.CoreLib/shared/System/AppContext.cs

   1 // Licensed to the .NET Foundation under one or more agreements.
   2 // The .NET Foundation licenses this file to you under the MIT license.
   3 // See the LICENSE file in the project root for more information.
   4
   5 using System.Collections.Generic;
   6 using System.Reflection;
   7 using System.Runtime.ExceptionServices;
   8 using System.Runtime.Loader;
   9 using System.Runtime.Versioning;
  10 using System.Threading;
  11
  12 namespace System
  13 {
  14     public static partial class AppContext
  15     {
  16         private static readonly Dictionary<string, object?> s_dataStore = new Dictionary<string, object?>();
  17         private static Dictionary<string, bool>? s_switches;
  18         private static string? s_defaultBaseDirectory;
  19
  20         public static string BaseDirectory =>
  21             // The value of APP_CONTEXT_BASE_DIRECTORY key has to be a string and it is not allowed to be any other type.
  22             // Otherwise the caller will get invalid cast exception
  23             (string?)GetData("APP_CONTEXT_BASE_DIRECTORY") ??
  24             (s_defaultBaseDirectory ??= GetBaseDirectoryCore());
  25
  26         public static string? TargetFrameworkName =>
  27             // The Target framework is not the framework that the process is actually running on.
  28             // It is the value read from the TargetFrameworkAttribute on the .exe that started the process.
  29             Assembly.GetEntryAssembly()?.GetCustomAttribute<TargetFrameworkAttribute>()?.FrameworkName;
  30
  31         public static object? GetData(string name)
  32         {
  33             if (name == null)
  34                 throw new ArgumentNullException(nameof(name));
  35
  36             object? data;
  37             lock (s_dataStore)
  38             {
  39                 s_dataStore.TryGetValue(name, out data);
  40             }
  41             return data;
  42         }
  43
  44         public static void SetData(string name, object? data)
  45         {
  46             if (name == null)
  47                 throw new ArgumentNullException(nameof(name));
  48
  49             lock (s_dataStore)
  50             {
  51                 s_dataStore[name] = data;
  52             }
  53         }
  54
  55 #pragma warning disable CS0067 // events raised by the VM
  56         public static event UnhandledExceptionEventHandler? UnhandledException;
  57
  58         public static event System.EventHandler<FirstChanceExceptionEventArgs>? FirstChanceException;
  59 #pragma warning restore CS0067
  60
  61         public static event System.EventHandler? ProcessExit;
  62
  63         internal static void OnProcessExit()
  64         {
  65             AssemblyLoadContext.OnProcessExit();
  66
  67             ProcessExit?.Invoke(AppDomain.CurrentDomain, EventArgs.Empty);
  68         }
  69
  70         /// <summary>
  71         /// Try to get the value of the switch.
  72         /// </summary>
  73         /// <param name="switchName">The name of the switch</param>
  74         /// <param name="isEnabled">A variable where to place the value of the switch</param>
  75         /// <returns>A return value of true represents that the switch was set and <paramref name="isEnabled"/> contains the value of the switch</returns>
  76         public static bool TryGetSwitch(string switchName, out bool isEnabled)
  77         {
  78             if (switchName == null)
  79                 throw new ArgumentNullException(nameof(switchName));
  80             if (switchName.Length == 0)
  81                 throw new ArgumentException(SR.Argument_EmptyName, nameof(switchName));
  82
  83             if (s_switches != null)
  84             {
  85                 lock (s_switches)
  86                 {
  87                     if (s_switches.TryGetValue(switchName, out isEnabled))
  88                         return true;
  89                 }
  90             }
  91
  92             if (GetData(switchName) is string value && bool.TryParse(value, out isEnabled))
  93             {
  94                return true;
  95             }
  96
  97             isEnabled = false;
  98             return false;
  99         }
 100
 101         /// <summary>
 102         /// Assign a switch a value
 103         /// </summary>
 104         /// <param name="switchName">The name of the switch</param>
 105         /// <param name="isEnabled">The value to assign</param>
 106         public static void SetSwitch(string switchName, bool isEnabled)
 107         {
 108             if (switchName == null)
 109                 throw new ArgumentNullException(nameof(switchName));
 110             if (switchName.Length == 0)
 111                 throw new ArgumentException(SR.Argument_EmptyName, nameof(switchName));
 112
 113             if (s_switches == null)
 114             {
 115                 // Compatibility switches are rarely used. Initialize the Dictionary lazily
 116                 Interlocked.CompareExchange(ref s_switches, new Dictionary<string, bool>(), null);
 117             }
 118
 119             lock (s_switches)
 120             {
 121                 s_switches[switchName] = isEnabled;
 122             }
 123         }
 124     }
 125 }