Interruptible promises?

[David Jeschke]

Has anyone done any work with interruptible promises? I'm thinking about the case where you have some long-running asynchronous processes managed by promises and want respond gracefully to Ctrl+C/SIGINT, SIGTERM, SIGHUP, SIGUSR1, etc. I've created a layer on top of Q where q.defer can take a callback function that is called in the case of an interrupt, where the callback is supposed to clean up and reject the deferred with a special interrupt error. I keep track of all of the interruptible promises and when a signal comes in the callbacks get called. I added interrupt-aware versions of q.all, q.delay, etc. I've also come across some use cases where it would be useful to be able to interrupt a specific promise. In my system any long-lived promises are interruptible and short-lived ones are ordinary uninterruptible Q promises. It seems to work pretty well but I'm sure I'm missing some things and I'd be a lot more comfortable if something like this were part of Q itself. Has anyone thought about this is detail?

[Domenic Denicola]

We've started down this road a few times, but never got to somewhere we were that comfortable with. "Cancellation" is usually what we call it.

The latest work that I am happy with is https://github.com/promises-aplus/cancellation-spec/issues/6. There are other discussions in that same issue tracker about other possibilities.

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From: q-con...@googlegroups.com [q-con...@googlegroups.com] on behalf of David Jeschke [djes...@gmail.com]
Sent: Wednesday, July 31, 2013 12:39
To: q-con...@googlegroups.com
Subject: [Q] Interruptible promises?

Has anyone done any work with interruptible promises? I'm thinking about the case where you have some long-running asynchronous processes managed by promises and want respond gracefully to Ctrl+C/SIGINT, SIGTERM, SIGHUP, SIGUSR1, etc. I've created a layer on top of Q where q.defer can take a callback function that is called in the case of an interrupt, where the callback is supposed to clean up and reject the deferred with a special interrupt error. I keep track of all of the interruptible promises and when a signal comes in the callbacks get called. I added interrupt-aware versions of q.all, q.delay, etc. I've also come across some use cases where it would be useful to be able to interrupt a specific promise. In my system any long-lived promises are interruptible and short-lived ones are ordinary uninterruptible Q promises. It seems to work pretty well but I'm sure I'm missing some things and I'd be a lot more comfortable if something like this were part of Q itself. Has anyone thought about this is detail?

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