public void clear(DiskRegion diskRegion, RegionVersionVector<DiskStoreID> regionVersionVector) {
    // call clear on each oplog
    Collection<Oplog> oplogsToClear = new ArrayList<>();
    synchronized (getOplogIdToOplog()) {
      oplogsToClear.addAll(getOplogIdToOplog().values());
      oplogsToClear.addAll(inactiveOplogs.values());

      Oplog child = getChild();
      if (child != null) {
        oplogsToClear.add(child);
      }
    }

    for (Oplog oplog : oplogsToClear) {
      oplog.clear(diskRegion, regionVersionVector);
    }

    if (regionVersionVector != null) {
      parent.getDiskInitFile().clearRegion(diskRegion, regionVersionVector);
    } else {
      long clearedOplogEntryId = getOplogEntryId();
      parent.getDiskInitFile().clearRegion(diskRegion, clearedOplogEntryId);
    }
  }
Destroy all the oplogs that are:

<pre>
1. the oldest (based on smallest oplog id)
2. empty (have no live values)
</pre>
geode-core/src/main/java/org/apache/geode/internal/cache/PersistentOplogSet.java