Performance improvement: improve Time Complexity from O(n) to O(1) in DataConversions#get in some cases

[yagagagaga]

The implement of DataConversions#get (by default) is as follows:

public V get(Object key) {
    Iterator<Entry<K,V>> i = entrySet().iterator();
    if (key==null) {
        while (i.hasNext()) {
            Entry<K,V> e = i.next();
            if (e.getKey()==null)
                return e.getValue();
        }
    } else {
        while (i.hasNext()) {
            Entry<K,V> e = i.next();
            if (key.equals(e.getKey()))
                return e.getValue();
        }
    }
    return null;
}

which means that you need to traverse all entities when find an entity. When there are lots of elements in the map, the cost of each operation is extremely high.

For example, it will show very clearly when you Import OSM data into PostGIS.

before improvement:

# take several hours or even more
baremaps workflow execute --file workflow.json

after improvement:

# take several seconds
baremaps workflow execute --file workflow.json

Of course, considering that org.apache.baremaps.data.collection.DataMap have different implementations and behaviors, this optimization is not applicable to all subclass.

[bchapuis]

Spot-on 🚀

It almost hurts 😅 I should have better tested the import before introducing the DataConversions utility.

As we can reintroduce JMH (Thank you @CalvinKirs for looking into this), it would be nice to include a couple of benchmarks or a mean to prevent this kind of regression in the future.