How to achieve an ordered Observable.merge()












1














I have to observables that don't complete



val firstObservable = ....
val secondObservable = ...


What I'm trying to achieve is some kind of ordered merge between these two observables, I have tried



Observable.merge(firstObservable, secondObservable) 


but this obviously does not guarantee the order of the items being preserved.
What first seemed to work for me it was:



Observable.concatArrayEager(firstObservable, secondObservable)


but since my observables don't complete the secondObservable never gets the chance to emit items. I have also tried



Observable.concatArrayEager(firstObservable.take(1), secondObservable.take(2))


but the problem with this approach is that all the other emissions are ignored. Has anyone any idea how to handle this kind of situation?
I would like to keep receiving items from my observable but also preserve order.



Observable.concatArrayEager(firstObservable, secondObservable)


seemed a good direction for me because it used to run my observables in parallel and performance is also important for me, but I'm not able to make it work and also keep the observables continuously emitting items



If you have any ideas please let me know. Thank you!










share|improve this question
























  • Can you provide an example of such custom logic with this operator?
    – Adrian
    Nov 21 '18 at 17:09






  • 2




    It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
    – dglozano
    Nov 21 '18 at 17:26
















1














I have to observables that don't complete



val firstObservable = ....
val secondObservable = ...


What I'm trying to achieve is some kind of ordered merge between these two observables, I have tried



Observable.merge(firstObservable, secondObservable) 


but this obviously does not guarantee the order of the items being preserved.
What first seemed to work for me it was:



Observable.concatArrayEager(firstObservable, secondObservable)


but since my observables don't complete the secondObservable never gets the chance to emit items. I have also tried



Observable.concatArrayEager(firstObservable.take(1), secondObservable.take(2))


but the problem with this approach is that all the other emissions are ignored. Has anyone any idea how to handle this kind of situation?
I would like to keep receiving items from my observable but also preserve order.



Observable.concatArrayEager(firstObservable, secondObservable)


seemed a good direction for me because it used to run my observables in parallel and performance is also important for me, but I'm not able to make it work and also keep the observables continuously emitting items



If you have any ideas please let me know. Thank you!










share|improve this question
























  • Can you provide an example of such custom logic with this operator?
    – Adrian
    Nov 21 '18 at 17:09






  • 2




    It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
    – dglozano
    Nov 21 '18 at 17:26














1












1








1







I have to observables that don't complete



val firstObservable = ....
val secondObservable = ...


What I'm trying to achieve is some kind of ordered merge between these two observables, I have tried



Observable.merge(firstObservable, secondObservable) 


but this obviously does not guarantee the order of the items being preserved.
What first seemed to work for me it was:



Observable.concatArrayEager(firstObservable, secondObservable)


but since my observables don't complete the secondObservable never gets the chance to emit items. I have also tried



Observable.concatArrayEager(firstObservable.take(1), secondObservable.take(2))


but the problem with this approach is that all the other emissions are ignored. Has anyone any idea how to handle this kind of situation?
I would like to keep receiving items from my observable but also preserve order.



Observable.concatArrayEager(firstObservable, secondObservable)


seemed a good direction for me because it used to run my observables in parallel and performance is also important for me, but I'm not able to make it work and also keep the observables continuously emitting items



If you have any ideas please let me know. Thank you!










share|improve this question















I have to observables that don't complete



val firstObservable = ....
val secondObservable = ...


What I'm trying to achieve is some kind of ordered merge between these two observables, I have tried



Observable.merge(firstObservable, secondObservable) 


but this obviously does not guarantee the order of the items being preserved.
What first seemed to work for me it was:



Observable.concatArrayEager(firstObservable, secondObservable)


but since my observables don't complete the secondObservable never gets the chance to emit items. I have also tried



Observable.concatArrayEager(firstObservable.take(1), secondObservable.take(2))


but the problem with this approach is that all the other emissions are ignored. Has anyone any idea how to handle this kind of situation?
I would like to keep receiving items from my observable but also preserve order.



Observable.concatArrayEager(firstObservable, secondObservable)


seemed a good direction for me because it used to run my observables in parallel and performance is also important for me, but I'm not able to make it work and also keep the observables continuously emitting items



If you have any ideas please let me know. Thank you!







android observable rx-java2






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 21 '18 at 17:41









Sarath Kn

1,613919




1,613919










asked Nov 21 '18 at 16:51









AdrianAdrian

62




62












  • Can you provide an example of such custom logic with this operator?
    – Adrian
    Nov 21 '18 at 17:09






  • 2




    It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
    – dglozano
    Nov 21 '18 at 17:26


















  • Can you provide an example of such custom logic with this operator?
    – Adrian
    Nov 21 '18 at 17:09






  • 2




    It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
    – dglozano
    Nov 21 '18 at 17:26
















Can you provide an example of such custom logic with this operator?
– Adrian
Nov 21 '18 at 17:09




Can you provide an example of such custom logic with this operator?
– Adrian
Nov 21 '18 at 17:09




2




2




It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
– dglozano
Nov 21 '18 at 17:26




It is quite confusing for me what you want to achieve. I don't understand what is the order you want to preserve if both are infinite streams. If you want to preserve the order in which the items were emitted, that's a merge operation. If you want to put all the emissions of one observable before the other, one of them has to have an end. If given one emission of one observable and one emission of the other observable, you want to decide the order of those two, then you can use a Zip. Please, explain with a concrete example what you want to achieve
– dglozano
Nov 21 '18 at 17:26












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