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javachroniclechronicle-map

Chroniclemap - fetch subset of keys

According to this answer ChronicleMap's entrySet().iterator() will dump all objects in memory.

I do not want to load all objects in memory and filter the entire map in memory - that defeats the purpose of chroniclemap.

So now, Given a chronicle map type <LongValue, Pojo>, and keys ranging from 0-1000 how would I -

  1. fetch keys ranging >= 500
  2. delete keys ranging <500
Solution

  • You can use a ThreadLocal to cache this value or create as needed.

    // cache as desired
LongValue key = Values.newHeapInstance(LongValue.class);

    To fetch many values without creating garbage

    // cached value for a Pojo
Pojo pojo = acquirePojo();

for (int i = 500; i < max; i++) {
    key.setValue(i);
    Pojo p2 = map.getUsing(key, pojo);
}

    This will create little or no garbage to remove entries

    for (int i = 0; i < 500 ; i++) {
    key.setValue(i);
    // assume map was built with removeReturnsNull(true)
    map.remove(key);
}