Efficiently matching two Flux - kotlin

Question

I have two Flux with 2 different data types as shown below:
Flux<Dog> dogs = loadDogsFromFile()
Flux<Man> men = loadMenFromFile()
data class Dog(
val name: String,
val ownerName: String,
)
data class Man(
val name: String,
val dogOwnerName: String,
)
As you can see the one field we can use to match these two Flux objects is dogOwnerName. Right now this is how I am comparing them
val disposable = dogs.flatMap { dog ->
men.map { man->
val isEqual = comparator(dog, man)
Triple(dog, man, isEqual)
}
}.filter {x -> x.third === true }
This gets the job done but it is nowhere efficient, it keeps looping even after the desired fields are found and because of that, we have to use a filter operator to only get what we need.
Edit
Based on #marstran comment on the user input, I have large JSON files that contain dogs and men that I'm loading here:
Flux<Dog> dogs = loadDogsFromFile()
Flux<Man> men = loadMenFromFile()
After matching the dogs to their owners/men I'm building an object that I'm saving to the database like this:
val disposable = dogs.flatMap { dog ->
men.map { man->
val isEqual = comparator(dog, man)
Triple(dog, man, isEqual)
}
}.filter {x -> x.third === true }
.map{(dog,man,isEqual) ->
DogOwner(man,dog)
}.doOnNext{dogOwner -> dogOwnerRepository.save(dogOwner)}

Answer 1

Consider using method take(long n, boolean limitRequest) from Flux:
public final Flux<T> take(long n,
boolean limitRequest)
Take only the first N values from this Flux, if available.
using it will allow you to break iterating over man once owner would be found.
https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Flux.html#take-long-boolean-
Take a look at this java example. I assume that dog and his owner have same value.
#Test
void dog_owner_test() {
int COUNT = 10000;
Flux<Integer> dogs = Flux.range(0, COUNT);
Flux<Integer> man = Flux.range(0, COUNT);
dogs.flatMap(
dog ->
man.map(m -> Tuples.of(dog, m))
.filter(tuple -> tuple.getT1().equals(tuple.getT2()))
.map(tuple -> new DogOwner(tuple.getT1(), tuple.getT2()))
.take(1, true)
)
.doOnNext(System.out::println)
// here you can save DogOwner to db
.as(StepVerifier::create)
.expectNextCount(COUNT)
.verifyComplete();
}
private static class DogOwner {
DogOwner(Integer dog, Integer owner) {
this.dog = dog;
this.owner = owner;
}
Integer dog;
Integer owner;
#Override
public String toString() {
return "DogOwner{" +
"dog=" + dog +
", owner=" + owner +
'}';
}
}