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[release/7.0] Remove locks from COM events delegate management. #76034

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Merged
merged 9 commits into from
Sep 27, 2022
Merged

[release/7.0] Remove locks from COM events delegate management. #76034

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dcb15f9
Remove locks from COM events delegate management.
AaronRobinsonMSFT Sep 19, 2022
281af27
Remove uses of var.
AaronRobinsonMSFT Sep 19, 2022
a8f94f4
Use array instead of List<T>
AaronRobinsonMSFT Sep 20, 2022
65f3e24
Revert "Use array instead of List<T>"
AaronRobinsonMSFT Sep 20, 2022
95775d7
Revert "Revert "Use array instead of List<T>""
AaronRobinsonMSFT Sep 21, 2022
f202cc7
Remove usage of `Delegate.Combine`. Upon deeper inspection there does…
AaronRobinsonMSFT Sep 21, 2022
cab29e5
Use some sugar
AaronRobinsonMSFT Sep 21, 2022
a2cc1ee
Simplify the RemoveAll scenario.
AaronRobinsonMSFT Sep 21, 2022
d7c3b43
Style nits.
AaronRobinsonMSFT Sep 22, 2022
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108 changes: 36 additions & 72 deletions src/libraries/Common/src/System/Runtime/InteropServices/ComEventsMethod.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using System.Reflection;

namespace System.Runtime.InteropServices
Expand Down Expand Up @@ -99,7 +100,7 @@ private void PreProcessSignature()
/// Since multicast delegate's built-in chaining supports only chaining instances of the same type,
/// we need to complement this design by using an explicit linked list data structure.
/// </summary>
private readonly List<DelegateWrapper> _delegateWrappers = new List<DelegateWrapper>();
private DelegateWrapper[] _delegateWrappers = Array.Empty<DelegateWrapper>();

private readonly int _dispid;
private ComEventsMethod? _next;
Expand Down Expand Up @@ -154,48 +155,36 @@ public static ComEventsMethod Add(ComEventsMethod? methods, ComEventsMethod meth

public bool Empty
{
get
{
lock (_delegateWrappers)
{
return _delegateWrappers.Count == 0;
}
}
get => _delegateWrappers.Length == 0;
}

public void AddDelegate(Delegate d, bool wrapArgs = false)
{
lock (_delegateWrappers)
DelegateWrapper[] wrappers, newWrappers;
do
{
// Update an existing delegate wrapper
foreach (DelegateWrapper wrapper in _delegateWrappers)
{
if (wrapper.Delegate.GetType() == d.GetType() && wrapper.WrapArgs == wrapArgs)
{
wrapper.Delegate = Delegate.Combine(wrapper.Delegate, d);
return;
}
}

var newWrapper = new DelegateWrapper(d, wrapArgs);
_delegateWrappers.Add(newWrapper);
}
wrappers = _delegateWrappers;
newWrappers = new DelegateWrapper[wrappers.Length + 1];
wrappers.CopyTo(newWrappers, 0);
newWrappers[^1] = new DelegateWrapper(d, wrapArgs);
} while (!PublishNewWrappers(newWrappers, wrappers));
}

public void RemoveDelegate(Delegate d, bool wrapArgs = false)
{
lock (_delegateWrappers)
DelegateWrapper[] wrappers, newWrappers;
do
{
wrappers = _delegateWrappers;

// Find delegate wrapper index
int removeIdx = -1;
DelegateWrapper? wrapper = null;
for (int i = 0; i < _delegateWrappers.Count; i++)
for (int i = 0; i < wrappers.Length; i++)
{
DelegateWrapper wrapperMaybe = _delegateWrappers[i];
if (wrapperMaybe.Delegate.GetType() == d.GetType() && wrapperMaybe.WrapArgs == wrapArgs)
DelegateWrapper wrapperMaybe = wrappers[i];
if (wrapperMaybe.Delegate == d && wrapperMaybe.WrapArgs == wrapArgs)
{
removeIdx = i;
wrapper = wrapperMaybe;
break;
}
}
Expand All @@ -206,67 +195,42 @@ public void RemoveDelegate(Delegate d, bool wrapArgs = false)
return;
}

// Update wrapper or remove from collection
Delegate? newDelegate = Delegate.Remove(wrapper!.Delegate, d);
if (newDelegate != null)
{
wrapper.Delegate = newDelegate;
}
else
{
_delegateWrappers.RemoveAt(removeIdx);
}
}
newWrappers = new DelegateWrapper[wrappers.Length - 1];
wrappers.AsSpan(0, removeIdx).CopyTo(newWrappers);
wrappers.AsSpan(removeIdx + 1).CopyTo(newWrappers.AsSpan(removeIdx));
} while (!PublishNewWrappers(newWrappers, wrappers));
}

public void RemoveDelegates(Func<Delegate, bool> condition)
{
lock (_delegateWrappers)
DelegateWrapper[] wrappers, newWrappers;
do
{
// Find delegate wrapper indexes. Iterate in reverse such that the list to remove is sorted by high to low index.
List<int> toRemove = new List<int>();
for (int i = _delegateWrappers.Count - 1; i >= 0; i--)
{
DelegateWrapper wrapper = _delegateWrappers[i];
Delegate[] invocationList = wrapper.Delegate.GetInvocationList();
foreach (Delegate delegateMaybe in invocationList)
{
if (condition(delegateMaybe))
{
Delegate? newDelegate = Delegate.Remove(wrapper!.Delegate, delegateMaybe);
if (newDelegate != null)
{
wrapper.Delegate = newDelegate;
}
else
{
toRemove.Add(i);
}
}
}
}

foreach (int idx in toRemove)
{
_delegateWrappers.RemoveAt(idx);
}
wrappers = _delegateWrappers;
List<DelegateWrapper> tmp = new(wrappers);
tmp.RemoveAll(w => condition(w.Delegate));
newWrappers = tmp.ToArray();
}
while (!PublishNewWrappers(newWrappers, wrappers));
}

public object? Invoke(object[] args)
{
Debug.Assert(!Empty);
object? result = null;

lock (_delegateWrappers)
foreach (DelegateWrapper wrapper in _delegateWrappers)
{
foreach (DelegateWrapper wrapper in _delegateWrappers)
{
result = wrapper.Invoke(args);
}
result = wrapper.Invoke(args);
}

return result;
}

// Attempt to update the member wrapper field
private bool PublishNewWrappers(DelegateWrapper[] newWrappers, DelegateWrapper[] currentMaybe)
{
return Interlocked.CompareExchange(ref _delegateWrappers, newWrappers, currentMaybe) == currentMaybe;
}
}
}