public boolean runIfAbsent(DataRegionId regionId, Runnable runnable) {
    final AtomicBoolean result = new AtomicBoolean(false);
    dataRegionMap.computeIfAbsent(
        regionId,
        k -> {
          runnable.run();
          result.set(true);
          return null;
        });
    return result.get();
  }
run the runnable if the region is absent. if the region is present, do nothing.

<p>we don't use computeIfAbsent because we don't want to create a new region if the region is
absent, we just want to run the runnable in a synchronized way.

@return true if the region is absent and the runnable is run. false if the region is present.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/StorageEngine.java