private Oplog getOldestLiveOplog() {
    Oplog result = null;
    synchronized (getOplogIdToOplog()) {
      for (Oplog oplog : getOplogIdToOplog().values()) {
        if (result == null || oplog.getOplogId() < result.getOplogId()) {
          result = oplog;
        }
      }

      // since the inactiveOplogs map is an LRU we need to check each one
      for (Oplog oplog : inactiveOplogs.values()) {
        if (result == null || oplog.getOplogId() < result.getOplogId()) {
          result = oplog;
        }
      }
    }

    return result;
  }
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