[jira] [Commented] (CASSANDRA-9334) Returning null from a trigger does not abort the write

["Sam Tunnicliffe (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-9334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14534813#comment-14534813 ] 

Sam Tunnicliffe commented on CASSANDRA-9334:
--------------------------------------------

Well, it's been this way since triggers were introduced. The initial implementation of {{StorageProxy#mutateWithTriggers}}

{code}
public static void mutateWithTriggers(Collection<? extends IMutation> mutations, ConsistencyLevel consistencyLevel, boolean mutateAtomically) throws WriteTimeoutException, UnavailableException,
        OverloadedException, InvalidRequestException
{
    Collection<RowMutation> tmutations = TriggerExecutor.instance.execute(mutations);
    if (mutateAtomically || tmutations != null)
    {
        Collection<RowMutation> allMutations = (Collection<RowMutation>) mutations;
        if (tmutations != null)
            allMutations.addAll(tmutations);
        StorageProxy.mutateAtomically(allMutations, consistencyLevel);
    }
    else
    {
        StorageProxy.mutate(mutations, consistencyLevel);
    }
}
{code}

So I would say it's a bug in the javadoc. 
Do you think it's a valid use case to be able to abort the entire mutation via a trigger?

> Returning null from a trigger does not abort the write
> ------------------------------------------------------
>
>                 Key: CASSANDRA-9334
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9334
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Brandon Williams
>            Assignee: Sam Tunnicliffe
>             Fix For: 2.0.x
>
>
> The javadoc for ITrigger seems to indicate that returning null means no mutations for the write will be applied at all:
> {noformat}
>      * Called exactly once per CF update, returned mutations are atomically updated.
>      *
>      * @param key - Row Key for the update.
>      * @param update - Update received for the CF
>      * @return modifications to be applied, null if no action to be performed.
> {noformat}
> and indeed, TriggerExecutor.execute seems to have code for this:
> {noformat}
>         if (augmentedMutations == null)
>             return null;
> {noformat}
> but it never fires.  In testing with a trigger that always returns null, the original mutation is still applied.



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