PagingPredicate, - returning duplicated elements, resulting in infinite loop.

[Danny-Hazelcast]

RP #3042 show Junit test for this issue.

issue first discovered while making a stabilizer test, around queries and indexes.

looks like range predicates, run on a map with Ordered Indexes, don't work as expected

[mesutcelik]

related failing tests on master.
https://hazelcast-l337.ci.cloudbees.com/job/Hazelcast-3.x-problematicTest/214/com.hazelcast$hazelcast-client/testReport/

It seems the issue must be forward ported to the master branch.

 com.hazelcast.client.map.ClientSortLimitTest.mapPagingPredicate_EmployObject_WithOrderedIndex_smalltest    0.19 sec    1
 com.hazelcast.client.map.ClientSortLimitTest.mapPagingPredicate_EmployObject_WithOrderedIndex_largetest    4.6 sec 1
 com.hazelcast.client.map.ClientSortLimitTest.equalsPred_withEmploye_test   1 min 0 sec 2
 com.hazelcast.client.map.ClientSortLimitTest.betweenPaginPred_withEmploye_test 1 min 0 sec 2
 com.hazelcast.client.map.ClientSortLimitTest.lessThanPred_withEmploye_test

[awara2012]

Maybe the method -- "hashCode()"(it's called in the "SortingUtil.compare()".), inheriting from the "Object", is the cause of the incorrect result when using the "PagingPredicate". (The hash code of the same "anchor" in the same "PagingPredicate" will be different at two query requests.)

[serkan-ozal]

The issue is about the wrong hashcode comparison.

Suppose that
i1 = -500.000.000
i2 = 2.000.000.000

Normally "i1 < i2", but if we use "i1 - i2" for comparison
i1 - i2 = -500.000.000 - 2.000.000.000 and we may accept result as "-2.500.000.000".
But the actual result is "1.794.967.296" because of overflow between
positive and negative integer bounds.

So, if we use "i1 - i2" for comparison, since result is greater than 0,
"i1" is accepted as bigger that "i2". But in fact "i1" is smaller than "i2".
Therefore, "i1 - i2" is not good way for comparison way between signed integers.

So comparison must be like this

...
int result = compareIntegers(comparable1.hashCode(), comparable2.hashCode());
...
private static int compareIntegers(int i1, int i2) {
        // "return i1 - i2" is not good way for comparison
        if (i1 > i2) {
            return +1;
        } else if (i2 > i1) {
            return -1;
        } else {
            return 0;
        }
}

Please see PR #3334

[Danny-Hazelcast]

@serkan-ozal @mdogan
I am reopening this issue as paging predicates are still broken,
see this PR #3409 for updated tests

looks like paging predicate is still producing duplicate results

[mdogan]

Closed by #3427

[ihsandemir]

related to #9968