https://github.com/Terracotta-OSS/offheap-store/: A library that offers data structures allocated off the java heap. 
public interface org.terracotta.offheapstore.disk.persistent.PersistentStorageEngine<K, V> extends org.terracotta.offheapstore.storage.StorageEngine<K, V>, org.terracotta.offheapstore.disk.persistent.Persistent
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.terracotta.offheapstore.disk.persistent.PersistentStorageEngine
  super_class: java.lang.Object
{
}
Signature: <K:Ljava/lang/Object;V:Ljava/lang/Object;>Ljava/lang/Object;Lorg/terracotta/offheapstore/storage/StorageEngine<TK;TV;>;Lorg/terracotta/offheapstore/disk/persistent/Persistent;
SourceFile: "PersistentStorageEngine.java"