[jira] [Commented] (HBASE-5827) [Coprocessors] Observer notifications on exceptions

["Andrew Purtell (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-5827?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401758#comment-13401758 ] 

Andrew Purtell commented on HBASE-5827:
---------------------------------------

bq. Assume the PUT(and related things) that i created in preBatchPut is also needed while i use the preWALWrite, is there any way i can carry it in one flow?

You can package the WAL observer and the region observer in the same JAR and they can use any way you'd like to pass state between, perhaps by way of a singleton. Does this work? 
                
> [Coprocessors] Observer notifications on exceptions
> ---------------------------------------------------
>
>                 Key: HBASE-5827
>                 URL: https://issues.apache.org/jira/browse/HBASE-5827
>             Project: HBase
>          Issue Type: Improvement
>          Components: coprocessors
>            Reporter: Andrew Purtell
>            Assignee: Andrew Purtell
>
> Benjamin Busjaeger wrote on dev@:
> {quote}
> Is there a reason that RegionObservers are not notified when a get/put/delete fails? Suppose I maintain some (transient) state in my Coprocessor that is created during preGet and discarded during postGet. If the get fails, postGet is not invoked, so I cannot remove the state.
> If there is a good reason, is there any other way to achieve the same thing? If not, would  it be possible to add something the snippet below to the code base?
> {code}
>     // pre-get CP hook
>     if (withCoprocessor && (coprocessorHost != null)) {
>       if (coprocessorHost.preGet(get, results)) {
>         return results;
>       }
>     }
> +    try{
>     ...
> +    } catch (Throwable t) {
> +        // failed-get CP hook
> +        if (withCoprocessor && (coprocessorHost != null)) {
> +          coprocessorHost.failedGet(get, results);
> +        }
> +        rethrow t;
> +    }
>     // post-get CP hook
>     if (withCoprocessor && (coprocessorHost != null)) {
>       coprocessorHost.postGet(get, results);
>     }
> {code}
> {quote}

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