Leaderboard TOP N
In game servers, there are many ranking-related tasks, such as retrieving TOP N operations for player level rankings, money rankings, combat power rankings, and more. While these can be implemented using relational databases, the sorting pressure on the database increases as the volume of data grows.
For Redis, these operations are straightforward. Even if you have millions of users generating millions of new scores every minute, Redis can handle these tasks effortlessly.
You only need jedis.zrevrank(key,member);
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ThreadLocalRandom;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.Tuple;
public class HelloWorldApp {
static int TOTAL_SIZE = 10000;
// Obtain a random name composed of lowercase letters of length 8
public static String randomName(int length) {
StringBuilder builder = new StringBuilder(length);
for (int i = 0; i < length; i++) {
builder.append((char) ThreadLocalRandom.current().nextInt(97,122));//a~z
}
return builder.toString();
}
public static void main(String[] args)
{
// Connection information can be obtained from the console
String host = "127.0.0.1";
int port = 10011;
Jedis jedis = new Jedis(host, port);
// Leaderboard application, perform the TOP N operation
try {
//Key
String key = "Game Leaderboard!";
//Clear possible existing data
jedis.del(key);
//Simulate generating a number of game players
List<String> playerList = new ArrayList<String>();
for (int i = 0; i < TOTAL_SIZE; ++i)
{
//Randomly generate the name of each player
playerList.add(randomName(8));
}
System.out.println("Input all " + TOTAL_SIZE +" players ");
//Record the score of each player
for (int i = 0; i < playerList.size(); i++)
{
//Random number generation, simulating the game score of the player
int score = (int)(Math.random()*5000);
String member = playerList.get(i);
if (i < 10) {
System.out.println("Player name：" + member + "， Player score: " + score
);
}
//Add the player's name and score to the corresponding key's SortedSet
jedis.zadd(key, score, member);
}
System.out.println("More player scores......");
//Get the sorted player list from the SortedSet of the corresponding key
Set<Tuple> scoreList = jedis.zrevrangeWithScores(key, 0, -1);
//Print out the Top 100 player leaderboard rankings
System.out.println();
System.out.println(" "+key);
System.out.println(" Top 100 Players");
scoreList = jedis.zrevrangeWithScores(key, 0, 99);
for (Tuple item : scoreList) {
System.out.println("Player name："+item.getElement()+"， Player score:"+Doubl
e.valueOf(item.getScore()).intValue());
}
//Output the ranking of a certain player
String player = playerList.get(0);
System.out.println();
System.out.println(" "+key);
System.out.println(" Player "+player+" ranking: "+ jedis.zrevrank(key,player));
} catch (Exception e) {
e.printStackTrace();
}finally{
jedis.quit();
jedis.close();
}
}
}Output：
Input all 10000 players
Player name：hegmsrcs， Player score: 1191
Player name：ocvhhxke， Player score: 653
Player name：ekgdllwj， Player score: 694
Player name：kxwsnnjj， Player score: 2051
Player name：vjflcktn， Player score: 2100
Player name：jtrlmnlk， Player score: 4257
Player name：aatbchgk， Player score: 2912
Player name：phukvvxy， Player score: 2044
Player name：aqqdqnel， Player score: 1859
Player name：hyndvsen， Player score: 2381
More player scores......
Game Leaderboard!
Top 100 Players
Player name：kqyhxehe， Player score:4999
Player name：datnveli， Player score:4998
Player name：ovxfislm， Player score:4997
Player name：llqnigun， Player score:4997
Player name：ckikmasa， Player score:4997
Player name：wlmdrpnx， Player score:4996
Player name：trslhgga， Player score:4996
Player name：bkbfnutg， Player score:4996
Player name：yqesafda， Player score:4995
Player name：grtjbjrq， Player score:4995
More player rankings......
Game Leaderboard!
Player hegmsrcs ranking: 7618