CODEWITHSUNDEEP
javaasynchronousconcurrencyplayframework
user2469133
user2469133

Reputation: 1970

Java play framework Async operation on same object

I'm trying to perform Async operations on the same object for example I would pass List to Promise to perform concurrently 3 queries where each query when finishes adds queried results to the List and finally the http result returns the Full list when all concurrent queries results finish.

Having a look at this tutorial:

https://www.playframework.com/documentation/2.2.x/JavaAsync

I could make something like this 

    return async(
            promise(new Function0<Integer>() {
                public Integer apply() {
                    firstQuery();
                }
            })
            . promise(new Function0<Integer>() {
                public Integer apply() {
                    return secondQuery();
                }
            })

            .map(new Function<Integer,Result>() {
                public Result apply(Integer i) {
                    Logger.debug("we have got "+i);
                return ok("Got " + i);
                }
            })     
        );

to make 2 operations work concurrently , but neither I could pass an object to promise and neither I can get the result of both queries to handle both results.

Upvotes: 1

Views: 124

Answers (1)

Salem
Salem

Reputation: 12986

You can use Promise.sequence to achieve that

F.Promise<Integer> one, two;
one = F.Promise.promise(new F.Function0<Integer>() {
    @Override public Integer apply() throws Throwable {
        return 20;
    }
});
two = F.Promise.promise(new F.Function0<Integer>() {
    @Override public Integer apply() throws Throwable {
        return 22;
    }
});
return F.Promise.sequence(one, two).map(new F.Function<List<Integer>, Result>() {
    @Override
    public Result apply(List<Integer> integers) throws Throwable {
        int res = integers.get(0) + integers.get(1);
        return ok("The answer is " + res);
    }
});

Upvotes: 1

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