[jira] [Moved] (MAPREDUCE-2814) Relax the strict type check by allowing subclasses pass the check

["Eli Collins (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAPREDUCE-2814?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Eli Collins moved HADOOP-5452 to MAPREDUCE-2814:
------------------------------------------------

    Issue Type: Bug  (was: Improvement)
           Key: MAPREDUCE-2814  (was: HADOOP-5452)
       Project: Hadoop Map/Reduce  (was: Hadoop Common)

> Relax the strict type check by allowing subclasses pass the check
> -----------------------------------------------------------------
>
>                 Key: MAPREDUCE-2814
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2814
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: He Yongqiang
>
> The type check like:
> {code}
> if (key.getClass() != keyClass)
>         throw new IOException("wrong key class: "+key.getClass().getName()
>                               +" is not "+keyClass);
> if (val.getClass() != valClass)
>         throw new IOException("wrong value class: "+val.getClass().getName()
>                               +" is not "+valClass);
> {code}
> is used a lot when a type check is needed. 
> I found their uses in org.apache.hadoop.io.SequenceFile, org.apache.hadoop.mapred.IFile, org.apache.hadoop.mapred.MapTask. Because i search with(key.getClass() != keyClass), so these codes may also appear in other classes.
> I suggest we can relax the strict type check by using 
> {code}
> if (key.getClass().isAssignableFrom(keyClass))
> {code}
> The error in my situation is listed below:
> {panel:borderStyle=dashed| borderColor=#ccc| titleBGColor=#F7D6C1| bgColor=#FFFFCE}
> java.io.IOException: Type mismatch in value from map: expected cn.ac.ict.vega.type.Type, recieved cn.ac.ict.vega.type.Type$Float
> 	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:553)
> 	at cn.ac.ict.vega.parse.mapreduce.block.FilterColumnBlockMapper.map(FilterColumnBlockMapper.java:77)
> 	at cn.ac.ict.vega.parse.mapreduce.block.BlockMapRunner.run(BlockMapRunner.java:33)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:332)
> 	at org.apache.hadoop.mapred.Child.main(Child.java:155)
> {panel} 
> Float is a sub class of Type. I wish it can pass the check. I use Type instead of Float is because i can not determint exactly whether it is Float, String or  some others.

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