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Add notes regarding using inline delegates with Scheduler.AddOnce #6023

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Oct 10, 2023
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2 changes: 2 additions & 0 deletions osu.Framework.Tests/Threading/SchedulerTest.cs
Original file line number Diff line number Diff line change
Expand Up @@ -429,6 +429,8 @@ public void TestAddOnceInlineDelegate()
{
classInvocations = 0;

// Note that while this works here (even with a capture), there's no guarantee that will always be the
// case. As such it's always best to use a local function or private method.
Comment on lines +432 to +433
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I'm... surprised that this works...

In this case the compiler has somehow decided that it can correctly reduce the inline delegate to a method group:

1696945472

For comparison, an actual method group:

1696945522

Wizardry I tell ya...

for (int i = 0; i < 10; i++)
invokeInlineDelegateAction();

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2 changes: 1 addition & 1 deletion osu.Framework/Threading/Scheduler.cs
Original file line number Diff line number Diff line change
Expand Up @@ -368,7 +368,7 @@ public bool AddOnce<T>(Action<T> task, T data)
/// Adds a task which will only be run once per frame, no matter how many times it was scheduled in the previous frame.
/// </summary>
/// <remarks>The task will be run on the next <see cref="Update"/> independent of the current clock time.</remarks>
/// <param name="task">The work to be done.</param>
/// <param name="task">The work to be done. Avoid using inline delegates as they may not be cached, bypassing the once-per-frame guarantee.</param>
/// <returns>Whether this is the first queue attempt of this work.</returns>
public bool AddOnce(Action task)
{
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