21 replies

IIRC there is no way to launch a promise

IIRC there is no way to launch a promise in a durable object (from a request) in such a way that does not block a response? For example I am trying to ship logs from a custom logger async to loki, but i don't want that to block responding to a request

DanTheGoodmanOP•9/22/23, 4:28 PM

bascially .waitUntil but for DOs

sathoro•9/22/23, 4:49 PM

I think if you just call the promise and don't await it, it will still get processed in the background for up to 1 minute

DanTheGoodmanOP•9/22/23, 4:49 PM

but it blocks the response to the client though

Larry•9/22/23, 6:31 PM

This sounds a little like we're talking about output gates. IIRC, the output gate is only activated for storage operations that aren't awaited. If you make a fetch() call to an external service and you do not await it, I believe the response will happen even if the fetch() has not come back. That said, if you need certainty, I would ask @kentonv_cf

DDanTheGoodman but it blocks the response to the client though

kenton•9/22/23, 6:42 PM

It shouldn't, if you don't await it.

DanTheGoodmanOP•9/22/23, 6:43 PM

I though the output gate would block it… and it still will complete in the background before sleeping a do?

kenton•9/22/23, 6:44 PM

the output gate only blocks waiting for storage writes to hit disk; it doesn't wait for network requests

DanTheGoodmanOP•9/22/23, 6:45 PM

Awesome, but any running promises will resolve before the DO gets potentially unloaded?

DanTheGoodmanOP•9/22/23, 6:45 PM

Well exit not necessarily resolve

kenton•9/22/23, 6:45 PM

(and FWIW the output gate will actually block both responses and outgoing fetch()es, until all writes are durable)

DDanTheGoodman Awesome, but any running promises will resolve before the DO gets potentially un...

kenton•9/22/23, 6:46 PM

The DO will will wait at least 30 seconds (actually 70 seconds) for remaining I/O after the last client disconnects

kenton•9/22/23, 6:47 PM

essentially it automatically does waitUntil

kenton•9/22/23, 6:47 PM

which is why we removed the explicit waitUntil API

DanTheGoodmanOP•9/22/23, 6:47 PM

but it can be longer if the promise is still running?

kenton•9/22/23, 6:47 PM

if there is still a client waiting for a response, the DO will not be evicted at all

kenton•9/22/23, 6:47 PM

(well, unless hibernation is enabled for that request/response)

DanTheGoodmanOP•9/22/23, 6:48 PM

I'm thining more in the scenario where I do like:

storage.put()
sendLogsToLoki() // promise
return new Response()

storage.put()
sendLogsToLoki() // promise
return new Response()

where the sendLogsToLoki is a promise that does not block the client getting a response, but the DO wont unload until that promise resolves

DanTheGoodmanOP•9/22/23, 6:49 PM

so in theory the client could be disconnected already while that promise is still running due to retries or what ever

DanTheGoodmanOP•9/22/23, 6:49 PM

I think that's safe based on what's explained above? And that the sendLogsToLokisendLogsToLoki promise wont block the client from getting the response

kenton•9/22/23, 6:50 PM

the DO will be evicted some time after the last client disconnects, even if there are outgoing requests still in flight. Those requests will be canceled.

DanTheGoodmanOP•9/22/23, 6:50 PM

gotcha, thanks for clarifying

kenton•9/22/23, 6:50 PM

it's the same with waitUntil()waitUntil() BTW -- it has a 30-second limit

IIRC there is no way to launch a promise

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