Fast, easy, realtime metrics using Redis bitmaps

redis-bitmaps-1.java

import redis.clients.jedis.Jedis;
import java.util.BitSet;

Jedis redis = new Jedis("localhost");

public int uniqueCount(String action, String date) {
  String key = action + ":" + date;
  BitSet users = BitSet.valueOf(redis.get(key.getBytes()));
  return users.cardinality();
}