Shrink Task.Delay when used without Cancellation (2)

[benaadams]

Follow up to #22233

Task.Delay is commonly used without cancellation:

Task Delay(int) - API Port 22.6%
Task Delay(TimeSpan) - API Port 9.8%

Task Delay(int, CancellationToken) - API Port 5.6%
Task Delay(TimeSpan, CancellationToken) - API Port 9.3%

This shaves 24 bytes of allocation off that common path.

Using @SergeyTeplyakov's ObjectLayoutInspector and local copies of the internal objects to make it easier to inspect.

ObjectLayoutInspector.TypeLayout.PrintLayout<DelayPromiseWithCancellation>(recursively: true);
ObjectLayoutInspector.TypeLayout.PrintLayout<DelayPromise>(recursively: true);

Type layout for 'DelayPromiseWithCancellation'
Size: 88 bytes. Paddings: 7 bytes (%7 of empty space)
|==============================================================|
| Object Header (8 bytes)                                      |
|--------------------------------------------------------------|
| Method Table Ptr (8 bytes)                                   |
|==============================================================|
|   0-7: Delegate m_action (8 bytes)                           |
|--------------------------------------------------------------|
|  8-15: Object m_stateObject (8 bytes)                        |
|--------------------------------------------------------------|
| 16-23: TaskScheduler m_taskScheduler (8 bytes)               |
|--------------------------------------------------------------|
| 24-31: Object m_continuationObject (8 bytes)                 |
|--------------------------------------------------------------|
| 32-39: ContingentProperties m_contingentProperties (8 bytes) |
|--------------------------------------------------------------|
| 40-43: Int32 m_taskId (4 bytes)                              |
|--------------------------------------------------------------|
| 44-47: Int32 m_stateFlags (4 bytes)                          |
|--------------------------------------------------------------|
|    48: VoidTaskResult m_result (1 byte)                      |
|--------------------------------------------------------------|
| 49-55: padding (7 bytes)                                     |
|--------------------------------------------------------------|
| 56-63: TimerQueueTimer Timer (8 bytes)                       |
|--------------------------------------------------------------|
| 64-71: CancellationToken Token (8 bytes)                     |
|--------------------------------------------------------------|
| 72-87: CancellationTokenRegistration Registration (16 bytes) |
| |=====================================|                      |
| |   0-7: CallbackNode _node (8 bytes) |                      |
| |-------------------------------------|                      |
| |  8-15: Int64 _id (8 bytes)          |                      |
| |=====================================|                      |
|==============================================================|

To

Type layout for 'DelayPromise'
Size: 64 bytes. Paddings: 7 bytes (%10 of empty space)
|==============================================================|
| Object Header (8 bytes)                                      |
|--------------------------------------------------------------|
| Method Table Ptr (8 bytes)                                   |
|==============================================================|
|   0-7: Delegate m_action (8 bytes)                           |
|--------------------------------------------------------------|
|  8-15: Object m_stateObject (8 bytes)                        |
|--------------------------------------------------------------|
| 16-23: TaskScheduler m_taskScheduler (8 bytes)               |
|--------------------------------------------------------------|
| 24-31: Object m_continuationObject (8 bytes)                 |
|--------------------------------------------------------------|
| 32-39: ContingentProperties m_contingentProperties (8 bytes) |
|--------------------------------------------------------------|
| 40-43: Int32 m_taskId (4 bytes)                              |
|--------------------------------------------------------------|
| 44-47: Int32 m_stateFlags (4 bytes)                          |
|--------------------------------------------------------------|
|    48: VoidTaskResult m_result (1 byte)                      |
|--------------------------------------------------------------|
| 49-55: padding (7 bytes)                                     |
|--------------------------------------------------------------|
| 56-63: TimerQueueTimer Timer (8 bytes)                       |
|==============================================================|

/cc @stephentoub

[stephentoub]

Thanks. I was thinking of something slightly different. Away from my computer right now but will try it when I'm back.

[stephentoub]

@benaadams, I was thinking of something like this:
stephentoub@37378d5
Opinions? (This also addresses an existing race condition I noticed in the implementation.)

[benaadams]

Yeah, that looks much better

[benaadams]

Are you submitting PR with it?

[stephentoub]

Are you submitting PR with it?

Feel free to copy or cherry-pick, since you already have two PRs open 😄

[benaadams]

Done, went for first as my cherry-picking ability is still a bit primordial 😄