Svetlin Zarev created TOMEE-2085:
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Summary: AutoConfig::firstMatching sorting issue with java 8
Key: TOMEE-2085
URL: https://issues.apache.org/jira/browse/TOMEE-2085
Project: TomEE
Issue Type: Bug
Reporter: Svetlin Zarev
Java 8 changed the implementation of Collections.sort(). In java < 8 it always
allocated a new array which was used for the actual sorting, and then the list
was recreated with it's content. Starting with Jav a8, the sort() method
delegates to the concrete implementation of the concrete list. For arrya list
it works directly on the backing array, which violates the assumption of the
current comparator impl, that the backing array is not modified during the
actual sorting.
Test case
{code}
public final class Main {
public static void main(String[] args) {
final Random random = new Random();
final String prefix = "0";
for (int k = 0; k < 1000; k++) {
try {
final List<String> resourceIds = generateRandomData(random);
sort(prefix, resourceIds);
} catch (Exception e) {
System.out.println(e);
break;
}
System.out.println(k);
}
}
private static void sort(final String prefix, final List<String>
resourceIds) {
Collections.sort(resourceIds, new Comparator<String>() { // sort from
webapp to global resources
@Override
public int compare(final String o1, final String o2) { // don't
change global order, just put app scoped resource before others
if (o1.startsWith(prefix) && o2.startsWith(prefix)) {
return resourceIds.indexOf(o1) - resourceIds.indexOf(o2);
} else if (o1.startsWith(prefix)) {
return -1;
} else if (o2.startsWith(prefix)) {
return 1;
}
// make it stable with prefixed comparison + keep existing
ordering (bck compat)
return resourceIds.indexOf(o1) - resourceIds.indexOf(o2);
}
});
}
private static List<String> generateRandomData(Random random) {
final List<String> resourceIds = new ArrayList<>();
for (int i = 0; i < 5000; i++) {
resourceIds.add(Integer.toString(random.nextInt(3)) +
random.nextInt(1000));
}
return resourceIds;
}
}
{code}
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