Fix ebuckets stop indication during ebExpire() (#13287)

on active-expire of buckets, at function `ebExpire()` ->
`ebSegExpire()`, if callback `onExpireItem()` indicated to stop, Yet
iterator (iter) was wrongly already got updated to point to next item.
In turn the segment will be updated without current item.

src/ebuckets.c

@@ -436,10 +436,11 @@ static int ebSegExpire(FirstSegHdr *firstSegHdr,
 
  for (i = 0; (i < numItemsInSeg) && (info->itemsExpired < info->maxToExpire) ; ++i) {
  mIter = type->getExpireMeta(iter);
- eItem toDelete = iter;
- iter = mIter->next;
+
+ /* keep aside `next` before removing `iter` by onExpireItem */
+ eItem next = mIter->next;
  mIter->trash = 1;
- ExpireAction act = info->onExpireItem(toDelete, info->ctx);
+ ExpireAction act = info->onExpireItem(iter, info->ctx);
 
  /* if (act == ACT_REMOVE_EXP_ITEM)
  * then don't touch the item. Assume it got deleted */
@@ -452,9 +453,11 @@ static int ebSegExpire(FirstSegHdr *firstSegHdr,
 
  if (act == ACT_UPDATE_EXP_ITEM) {
  mIter->next = *updateList;
- *updateList = toDelete;
+ *updateList = iter;
  }
 
+ /* Item was REMOVED/UPDATED. Advance to `next` item */
+ iter = next;
  ++info->itemsExpired;
  firstSegHdr->totalItems -= 1;
  }
@@ -672,6 +675,7 @@ static int ebListExpire(ebuckets *eb,
  if (info->itemsExpired == info->maxToExpire)
  break;
 
+ /* keep aside `next` before removing `iter` by onExpireItem */
  eItem *next = metaItem->next;
  metaItem->trash = 1;
  ExpireAction act = info->onExpireItem(item, info->ctx);