[
https://issues.apache.org/jira/browse/KYLIN-4327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Yifei Wu updated KYLIN-4327:
----------------------------
Description:
in current TopN， it should save top(k) result and keep it in double value,
just like this:
```
public class Counter<T> implements Serializable{
...
protected T item;
protected double count;
...
}
```
But its Comparator method use "==" directly to compare the result, it may
cause the error "*violate its general contract*" when calling it
```
return o1.getCount() > o2.getCount() ? 1 : o1.getCount() ==
o2.getCount() ? 0 : -1;
```
was:
in current TopN， it should save top(k) result and keep it in double value,
just like this:
```
public class Counter<T> implements Serializable{
...
protected T item;
protected double count;
...
}
```
But its Comparator method use "==" directly to compare the result, it may
cause the error "*violate its general contract*" twhen calling it
```
return o1.getCount() > o2.getCount() ? 1 : o1.getCount() ==
o2.getCount() ? 0 : -1;
```
> TOPN Comparator may violate its general contract
> -------------------------------------------------
>
> Key: KYLIN-4327
> URL: https://issues.apache.org/jira/browse/KYLIN-4327
> Project: Kylin
> Issue Type: Improvement
> Reporter: Yifei Wu
> Assignee: Yifei Wu
> Priority: Minor
>
> in current TopN， it should save top(k) result and keep it in double value,
> just like this:
> ```
> public class Counter<T> implements Serializable{
> ...
> protected T item;
> protected double count;
> ...
> }
> ```
> But its Comparator method use "==" directly to compare the result, it may
> cause the error "*violate its general contract*" when calling it
> ```
> return o1.getCount() > o2.getCount() ? 1 : o1.getCount() ==
> o2.getCount() ? 0 : -1;
> ```
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