mono/tests/sgen-toggleref.cs

   1 using System;
   2 using System.Collections;
   3 using System.Collections.Generic;
   4 using System.Threading;
   5 using System.Runtime.InteropServices;
   6
   7 public class Toggleref {
   8         public int __test;
   9         public string id;
  10         public List<object> link = new List<object> ();
  11         public const int DROP = 0;
  12         public const int STRONG = 1;
  13         public const int WEAK = 2;
  14
  15         ~Toggleref () {
  16
  17         }
  18 }
  19
  20 [StructLayout (LayoutKind.Explicit)]
  21 public struct Helper {
  22         [FieldOffset(0)]
  23         IntPtr ptr;
  24         [FieldOffset(0)]
  25         object obj;
  26         public static IntPtr ObjToPtr (object obj)
  27         {
  28                 Helper h = default (Helper);
  29                 h.obj = obj;
  30                 return h.ptr;
  31         }
  32 }
  33
  34 class Driver {
  35         static WeakReference<Toggleref> root, child;
  36
  37         [DllImport ("__Internal", EntryPoint="mono_gc_toggleref_add")]
  38         static extern int mono_gc_toggleref_add (IntPtr ptr, bool strong_ref);
  39
  40         static void Register (object obj)
  41         {
  42                 mono_gc_toggleref_add (Helper.ObjToPtr (obj), true);
  43         }
  44
  45         static void SetupLinks () {
  46                 var a = new Toggleref () { id = "root" };
  47                 var b = new Toggleref () { id = "child" };
  48                 a.link.Add (b);
  49                 a.__test = Toggleref.STRONG;
  50                 b.__test = Toggleref.WEAK;
  51                 Register (a);
  52                 Register (b);
  53                 root = new WeakReference<Toggleref> (a, false);
  54                 child = new WeakReference<Toggleref> (b, false);
  55         }
  56
  57         static Toggleref a, b;
  58
  59         static int Main ()
  60         {
  61
  62                 var t = new Thread (SetupLinks);
  63                 t.Start ();
  64                 t.Join ();
  65
  66                 GC.Collect ();
  67                 GC.WaitForPendingFinalizers ();
  68
  69                 Console.WriteLine ("try get A {0}", root.TryGetTarget (out a));
  70                 Console.WriteLine ("try get B {0}", child.TryGetTarget (out b));
  71                 Console.WriteLine ("a is null {0}", a == null);
  72                 Console.WriteLine ("b is null {0}", b == null);
  73                 if (a == null || b == null)
  74                         return 1;
  75                 Console.WriteLine ("a test {0}", a.__test);
  76                 Console.WriteLine ("b test {0}", b.__test);
  77
  78                 //now we break the link and switch b to strong
  79                 a.link.Clear ();
  80                 b.__test = Toggleref.STRONG;
  81                 a = b = null;
  82
  83                 GC.Collect ();
  84                 GC.WaitForPendingFinalizers ();
  85
  86                 Console.WriteLine ("try get A {0}", root.TryGetTarget (out a));
  87                 Console.WriteLine ("try get B {0}", child.TryGetTarget (out b));
  88                 Console.WriteLine ("a is null {0}", a == null);
  89                 Console.WriteLine ("b is null {0}", b == null);
  90                 if (a == null || b == null)
  91                         return 2;
  92                 Console.WriteLine ("a test {0}", a.__test);
  93                 Console.WriteLine ("b test {0}", b.__test);
  94
  95
  96                 return 0;
  97
  98         }
  99 }