[tokio-util] AbortOnDropHandle::spawn shortcut

[stepancheg]

Motivation

Some code is written incorrectly: it spawns a task, but does not track whether task is still needed, e.g. request was not dropped. AbortOnDropHandle helps with this problem, but it is a bit unergonomic.

Solution

Add AbortOnDropHandle::spawn shortcut.

[ADD-SP]

This new interface will surprise downstream, and people will be confused by it because this isn't what AbortOnDropHandle is supposed to do.

Would you mind elaborating on your motivation? it's difficult for me to grasp the current motivation in the PR description.

• What are the challenges without this feature?
• How does this feature solve these challanges?

[stepancheg]

this isn't what AbortOnDropHandle is supposed to do.

I don't understand. What it is supposed to do?

What are the challenges without this feature?

99% of tasks I create needs abort on drop (and I guess, in many cases, other people should be doing that too). So shortcut this this common operation is desirable.

Shortcut can be member function of AbortOnDropHandle, or could be standalone function like spawn_abort_on_drop.

How does this feature solve these challenges?

This PR makes this common pattern more ergonomic.

[ADD-SP]

Shortcut can be member function of AbortOnDropHandle, or could be standalone function like spawn_abort_on_drop.

For existing interface, downstream have to do this.

let hdl = AbortOnDropHandle::new(tokio::spawn(...));

And you want a shortcut like this, is my understanding correct?

let hdl = AbortOnDropHandle::spawn(...);

If so, would you mind adding this kind of example to the PR description? I believe this can help reviewers to get the motivation in 10 seconds.

[stepancheg]

Added an example.

Now I understand the motivation.

[ADD-SP]

I searched the history of AbortOnDropHandle, there was a short discussion about AbortOnDropHandle::spawn, see #6786 (comment).

Initially, there was a AbortOnDropHandle::spawn, but it was removed before merging.

Shortcut can be member function of AbortOnDropHandle, or could be standalone function like spawn_abort_on_drop.

A standalone function spawn_abort_on_drop was also considered, but the AbortOnDropHandle::new was win.

I think having a shortcut is beneficial, but we need a approach which looks better than spawn_abort_on_drop.

[ADD-SP]

Thanks for your PR! I closed this PR as currently we don't have a better approach. Feel free to re-open this PR or open a new once once you have a better approach.