Fix InvalidOp when enumerating the SystemClockChanged hashset

akarnokd · akarnokd · commit c8897672470c · 2019-04-08T16:32:00.000+02:00
diff --git a/Rx.NET/Source/src/System.Reactive/Internal/SystemClock.cs b/Rx.NET/Source/src/System.Reactive/Internal/SystemClock.cs
@@ -59,7 +59,9 @@ private static void OnSystemClockChanged(object sender, SystemClockChangedEventA
         {
             lock (SystemClockChanged)
             {
-                foreach (var entry in SystemClockChanged)
+                // create a defensive copy as the callbacks may change the hashset
+                var copySystemClockChanged = new List<WeakReference<LocalScheduler>>(SystemClockChanged);
+                foreach (var entry in copySystemClockChanged)
                 {
                     if (entry.TryGetTarget(out var scheduler))
                     {

Original file line number	Diff line number	Diff line change
`@@ -59,7 +59,9 @@ private static void OnSystemClockChanged(object sender, SystemClockChangedEventA`
`59`	`59`	`{`
`60`	`60`	`lock (SystemClockChanged)`
`61`	`61`	`{`
`62`		`- foreach (var entry in SystemClockChanged)`
	`62`	`+ // create a defensive copy as the callbacks may change the hashset`
	`63`	`+ var copySystemClockChanged = new List<WeakReference<LocalScheduler>>(SystemClockChanged);`
	`64`	`+ foreach (var entry in copySystemClockChanged)`
`63`	`65`	`{`
`64`	`66`	`if (entry.TryGetTarget(out var scheduler))`
`65`	`67`	`{`