void notifyListeners() {
    final MemoryUsageListener[] savedListeners = memoryUsageListeners;

    if (savedListeners.length == 0) {
      return;
    }

    final long bytesUsed = getUsedMemory();
    for (final MemoryUsageListener savedListener : savedListeners) {
      savedListener.updateMemoryUsed(bytesUsed);
    }
  }
Return the slabId of the slab that contains the given addr.
geode-core/src/main/java/org/apache/geode/internal/offheap/MemoryAllocatorImpl.java