How to stop processing of DataImportHandler in EventListener

[Wenca]

Hi,

I have 2 DataImportHandlers configured. The first one prepares data to 
berkeley backed cache (SOLR-2382, SOLR-2613) and the second one then 
indexes documents reading subentity data from the cache.

I need some way to prevent the second handler to run if the first one is 
currently runnig to prevent reading any inconsistent data. I have't 
found any clear way to achieve this yet.

I thought I can use EventListener before the second handler that will 
check whether the cache dataimport is running and if so set some flag, 
that the processing should not continue.

Or is there another way to block data import handler when another one is 
running?

in solrconfig.xml I have:

<requestHandler name="/dataimport"
  class="org.apache.solr.handler.dataimport.DataImportHandler">
    <lst name="defaults">
      <str name="config">db-data-config.xml</str>
      <str name="persistCacheBaseDir">...</str>
    </lst>
</requestHandler>

<requestHandler name="/dih-cache"
  class="org.apache.solr.handler.dataimport.DataImportHandler">
    <lst name="defaults">
        <str name="config">cache-db-data-config.xml</str>
        <str name="writerImpl">
                org.apache.solr.handler.dataimport.DIHCacheWriter
        </str>
        <str name="persistCacheImpl">
                org.apache.solr.handler.dataimport.BerkleyBackedCache
        </str>
        <str name="persistCacheBaseDir">...</str>
        <str name="persistCacheName">data_cache</str>
        <str name="cachePk">id</str>
    </lst>
</requestHandler>

Thank wenca