var features = new ol.Collection(),
layer = new ol.layer.Vector({
    source: new ol.source.Vector({features: features}),
    style: function(feature, resolution){
        console.log("called it"); // <-- called twice for each feature
        return getStyle(feature);
    }
});
map.addLayer(layer);
var draw = new ol.interaction.Draw({
    features: features,
    type: (geomType)
});
map.addInteraction(draw);