batterseapower / btreemap Goto Github PK

Could the README include a memory usage comparison between TreeMap and BTreeMap?

I have been looking at your library, and it looks quite neat.
Thanks.
Would you consider adding a clone() method? Use case is to freeze a map state for further processing while continuing to mutate the original map.

This code:

    BTreeMap<Integer, Integer> map = BTreeMap.create();

    for (int i = 0; i < 1000; i++) {
      map.put(i, i);
    }

    for (int i = 0; i < 481; i++) {
      map.remove(i);
    }

    map.get(481);  // this line fails with NullPointerException

fails with exception:

Exception in thread "main" java.lang.NullPointerException
	at uk.co.omegaprime.btreemap.BTreeMap$Internal.find(BTreeMap.java:221)
	at uk.co.omegaprime.btreemap.BTreeMap.findLeaf(BTreeMap.java:491)
	at uk.co.omegaprime.btreemap.BTreeMap.getOrDefault(BTreeMap.java:501)
	at uk.co.omegaprime.btreemap.BTreeMap.get(BTreeMap.java:470)
	at Test.main(Test.java:22)

The code uses sun.misc.Unsafe which isn't supported anymore in Java 17:

The problem can be fixed by replacing it with jdk.internal.misc.Unsafe.objectFieldOffset but it would be better to altogether get rid of the usage of Unsafe.

It would be really nice to make constructors in BTreeMap public, so the API of BTreeMap will be the same as for TreeMap. Until, if I just want to try how things got faster with a BTreeMap in my project, I can't replace TreeMap with a BTreeMap automatically, since I need to manually replace all constructor calls with BTreeMap factory methods.