How to use GORM to automically update a group of objects

Question

I am using GORM standalone (groovyVersion = '2.0.8', grailsVersion = '2.2.4', gormVersion = '1.3.7', h2Version = '1.3.170') and have a database of objects which will be undergoing frequent concurrent modification.

These objects are grouped by one property, 'entry' and have another property 'process_flags' that I need to update. I want to update all of the process_flag settings of a group of the objects defined by having the same entry. (This will indicate to other processes that I am processing this group of objects.)

I presently try code like the following:

List<Item>  res = null
int triesRemaining = 10 // try locking a group this many times
while (res==null && triesRemaining > 0) {
  Item firstItem = Item.findByProcessFlags(Item.ProcessFlags.NEW)
  if (firstItem==null) return null
  res = Item.findAllByEntry(firstItem.entry)
  try {
    Item.withTransaction {transStatus->
      res.each {it->
        if (it.processFlags != Item.ProcessFlags.NEW) {
          throw new StaleObjectStateException(Item.class.toString(),it.id)
        }
        it.processFlags = Item.ProcessFlags.IN_PROCESS
        it.save(flush:true)
      }
    }
  } catch (HibernateOptimisticLockingFailureException e) {
    logger.debug("Caught HibernateOptimisticLockingFailureException. Trying new group.")
    res = null
    triesRemaining--
  }
return res

This results in a exception propagating up the stack, labelled as occurring at the res.each and as a StaleObjectStateException, though I presume is actually a HibernateOptimisticLockingFailureException, as per this discussion: How to handle GORM exceptions. Note that neither the class nor the method in which this code appears is annotated @Transactional.

So my questions are how to best handle this situation in code with frequent concurrent accesses? Is there a way to do it with catching a failure of optimistic locking? Or does this need to be handled with some pessimistic locking? And if so, can it still be handled with dynamic finders?

One very important item to note. The class PatchedDefaultEventListener, which is in Grails, is logging the exception as an error and then re-throwing it. This shows up in the log and is a bit confusing, because it looks like an exception being caught further along, but is not. The exception being thrown is a HibernateOptimisticLockingFailureException. — Peter N. Steinmetz, Jun 05 '14 at 18:43

score 0 · Answer 1 · answered Jun 01 '14 at 01:00

0

What you want to do is used a where query. The where method returns a DetachedCriteria instance, that allows you to perform a batch update:

 Item.where { entry == firstItem.entry }
     .updateAll(processFlags: Item.ProcessFlags.IN_PROCESS)

answered Jun 01 '14 at 01:00

Graeme Rocher

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How to use GORM to automically update a group of objects

1 Answers1