Hi, I have method with a callback, that will be ca...
# coroutinesp
pawelbochenski
12/19/2018, 7:18 AMHi, I have method with a callback, that will be called more then once. how to wrap it into coroutine?
b
bdawg.io
12/19/2018, 7:23 AMDo you need the result of each time the callback is invoked?
p
pawelbochenski
12/19/2018, 7:24 AMyes, there will be some data in callback that I need to handle
pawelbochenski
12/19/2018, 7:25 AMI was thinking about Channel, but I don’t know how to wrap it up
d
dave08
12/19/2018, 7:27 AMsuspendCancellableCoroutine { }p
pawelbochenski
12/19/2018, 7:38 AMsuspendCancellableCoroutine will not work, callback will be called more than once
g
gildor
12/19/2018, 7:39 AMThan you need channel, because you cannot use suspend functions to receive stream of events
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gildor
12/19/2018, 7:40 AMDepends on how this channel should work *buffer or drop events.
gildor
12/19/2018, 7:41 AMActually you just wrap callback, create a channel and send events to it using
send()offerd
dave08
12/19/2018, 7:42 AMPerhaps
produce { }g
gildor
12/19/2018, 7:42 AMbut offer is not suspending function, so have to decide what to do if offer is failed (channel is full)
gildor
12/19/2018, 7:42 AMyes, produce can be used, depends on what do you want as result API
gildor
12/19/2018, 7:43 AMalso if callback is asyncronous and you just use offer, you even don’t need produce (produce it’s channel + coroutine), but just a channel and callback
p
pawelbochenski
12/19/2018, 7:48 AM Copy code
fun subscribe(topic: String): Channel<String> {
val channel = Channel<String>()
client.subscribe(topic) { _, message ->
channel.offer(message.toString())
}
return channel
}pawelbochenski
12/19/2018, 7:48 AMis this enough?
pawelbochenski
12/19/2018, 7:48 AMI guess that callback is asynchronous
g
gildor
12/19/2018, 7:51 AMyes, but be careful, this is rendezvous channel, so if event will not be consumed, next offer will just drop data
gildor
12/19/2018, 7:51 AMas I said, it depends on your use case
gildor
12/19/2018, 7:51 AMif you want get all the events, use buffered channel instead
gildor
12/19/2018, 7:52 AMalso you do not handle channel cancellation, if your callback API provides some cancellation APIs you can integrate it with channel
p
pawelbochenski
12/19/2018, 7:55 AMok thanks a lot 🙂
s
streetsofboston
12/19/2018, 1:03 PM@pawelbochenski
See the discussion here:
https://kotlinlang.slack.com/archives/C1CFAFJSK/p1544020761136600?thread_ts=1544020761.136600&cid=C1CFAFJSK
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