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EXAMPLES.md

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Examples

Please note that the following examples do not show all the available options and features. Dive into the API documentation for more information.

❗ Note: Ranks are 1-based.

Basic leaderboard usage

Create a plain leaderboard:

const lb = new Leaderboard(client, 'lb:example', {
    sortPolicy: 'high-to-low',
    updatePolicy: 'replace'
});
  • client is the ioredis connection
  • lb:example is the Redis key of the sorted set.
  • sortPolicy is set to high-to-low, that means higher scores will be considered better
  • updatePolicy is set to best, that means when we update the leaderboard, it will only be updated if the score is better (depending on sortPolicy) than the previously stored score.
    Also replace and aggregate are supported.

Now we can start doing queries!
Let's add some entries:

await lb.update([
    { id: "player1", value: 17 },
    { id: "player2", value: 97 },
    { id: "player3", value: 43 },
    { id: "player4", value: 12 },
    { id: "player5", value: 58 }
]);

Psst: you can also specify an update policy to override the default for that update only.

Now query the entries, for example, the top 3:

await lb.top(3);
[
    { id: 'player2', score: 97, rank: 1 },
    { id: 'player5', score: 58, rank: 2 },
    { id: 'player3', score: 43, rank: 3 }
]

Awesome! Remember that you can also use bottom to retrieve the worst entries.

Now lets say we want to list a specific range of ranks, for example, from rank 3 to 5:

await lb.list(3, 5); // ranks are inclusive [lower, upper]
[
    { id: 'player3', score: 43, rank: 3 },
    { id: 'player1', score: 17, rank: 4 },
    { id: 'player4', score: 12, rank: 5 }
]

Now how to query entries around another entries. For example, the entries at distance 1 of player3:

await lb.around("player3", 1);
[
    { id: 'player5', score: 58, rank: 2 }, // dist 1
    { id: 'player3', score: 43, rank: 3 }, // center
    { id: 'player1', score: 17, rank: 4 }  // dist 1
]

Psst: you can change the behaviour of around near the borders, check the documentation!

Want to find a specific entry?

await lb.find("player5");
{ id: 'player5', score: 58, rank: 2 }

Want to remove bad entries?

await lb.remove(["player1", "player3", "player5"]); // odds are bad 😠

Want to know how many entries are in the leaderboard?

await lb.count();
2

Want to reset the leaderboard? (remove all entries)

await lb.clear();

Enough for an introduction!

Exporting a leaderboard

To export a Leaderboard, you call exportStream(batchSize) in a leaderboard object, which returns a Readable stream that lets you iterate every entry in the leaderboard:

const stream = lb.exportStream(1000);

stream.on("data", (entries) => {
    // process entries
});
stream.on("end", () => {
    // finished
});

If you want to do async work when you receive each batch (for example, insert the data into MySQL), then you should use the pause and resume functions in the stream:

stream.on("data", (entries) => {
    stream.pause();

    doSomeAsyncWork(entries).then(() => {
        // continue processing
        stream.resume();
    });
});

or with async/await:

stream.on("data", async (entries) => {
    stream.pause();
    await doSomeAsyncWork(entries);
    stream.resume();
});

Recurring leaderboards

Let's say you want to create a leaderboard that "resets" each month (for custom cycles see the custom cycles example). I say "reset" in quotes because the previous Redis Key is not deleted or altered when a cycle ends (a month). A new key is generated for each cycle identified by a CycleKey. If you want to delete or export previous leaderboards see the clean stale leaderboards example.

Create the periodic leaderboard:

const plb = new PeriodicLeaderboard(client, "plb:test", {
    leaderboardOptions: {
        sortPolicy: 'high-to-low',
        updatePolicy: 'replace'
    },
    cycle: 'monthly'
});

Now you use getLeaderboardNow to get the leaderboard for the current cycle (month in this case):

const lb = plb.getLeaderboardNow();

Now you can use lb as a regular leaderboard. You should call getLeaderboardNow every time you want to access the current leaderboard, to make sure you are always on the last cycle.

In the above example, the CycleKey was automatically handled. If you want, or have specific needs, you can use the following, which is equivalent:

const cycleKey = plb.getKeyNow(); // do something with this
const lb = plb.getLeaderboard(cycleKey);

What does a CycleKey look like?

  • yearly: y2020
  • weekly: w2650 (week number since epoch)
  • monthly: y2020-m05
  • daily: y2020-m05-d15
  • hourly: y2020-m05-d15-h22
  • minute: y2020-m05-d15-h22-m53

Custom cycles

You will have to pass a CycleFunction to the options object in the PeriodicLeaderboard constructor.
This function takes a time and returns the appropiate CycleKey that uniquely identifies the cycle that the time provided belongs to.

The provided time will be in local time, so you must return the appropiate cycle in local time. If you want to offset the time, please use the now function in the options.

Every 5 minutes

const cycleFunction = (time) => `y${time.getFullYear()}-m${time.getMonth()}-d${time.getDate()}-h${time.getHours()}-5m${Math.floor(time.getMinutes() / 5)}`;

Every 3 months

const cycleFunction = (time) => `y${time.getFullYear()}-m${Math.floor(time.getMonth() / 3)}`;

Every N days

This is a bit more complicated, because what happens when the cycle spans over a new year? Should the last cycle be shorter? Should always mantain the same number of days no matter what? (like weekly). On top of that, you have to think which day is the first day in the cycle.

If you just want to truncate the cycle at the end of the year:

const cycleFunction = (time) => `y${time.getFullYear()}-m${Math.floor(getDayOfTheYear(time) / N)}`;

Note that cycles will start on January 1st every year. You wil have to implement getDayOfTheYear yourself.

If you need that all cycles are fixed, you will have to rely on the number of days since epoch (this is how weekly works, check Defaults below):

const cycleFunction = (time) => `dN-${Math.floor(getDaySinceEpoch(time) / N)}`;

Of couse you can add an offset to make it start when you need. You will have to implement getDaySinceEpoch yourself.

Defaults

You can see how the default cycles are defined in the object CYCLE_FUNCTIONS in PeriodicLeaderboard.ts.

Pass cycle

const plb = new PeriodicLeaderboard(client, "plb:custom", {
    leaderboardOptions: { ... },
    cycle: cycleFunction
});

Clean stale leaderboards

You may get stale leaderboards by using periodic leaderboards. You can retrieve arbitrary cycles using getLeaderboardAt, or you may want to get every existing cycle.

You can retrieve existing cycles with getExistingKeys:

const keys = await plb.getExistingKeys();
[
    "y2020-m05-d01",
    "y2020-m05-d02",
    "y2020-m05-d03",
    "y2020-m05-d04"
]

Then you can iterate them and retrieve the corresponding leaderboard for each one:

for(let key of keys) {
    if(key !== plb.getKeyNow()) { // you can check if this is not the active leaderboard
        const lb = plb.getLeaderboard(key);
        // export it, delete it
    }
}

Psst: you should compute getKeyNow outside the loop.

Matrix of leaderboards

A matrix of leaderboards is defined by its dimensions and features. A dimension represents an abstract group (region, level, map) with optionally a cycle (weekly, monthly). A feature is a unit, for example, a score, number of kills, seconds survived, coins collected, etc.

Let's say we want to create a leaderboard for a game with 5 dimensions:

  • world: a permanent leaderboard for everyone
  • us: a permanent, country specific leaderboard
  • best-month, best-week, best-day: global, recurring leaderboards

And some features, lets say:

  • kills: accumulated number of kills (higher is better)
  • coins: accumulated coins collected (higher is better)
  • best-kills: best number of kill in the same game (higher is better)
  • best-time: best time (in seconds) taken to complete a level (lower is better)

The leaderboard matrix for the game would look like this:

kills coins best-kills best-time
world ... ... ... ...
us ... ... ... ...
best-month ... ... ... ...
best-week ... ... ... ...
best-day ... ... ... ...

And in code, this looks like:

const mlb = new LeaderboardMatrix(client, "gamelb", {
    dimensions: [
        { name: "world" },
        { name: "us" },
        { name: "best-month", cycle: 'monthly' },
        { name: "best-week", cycle: 'weekly' },
        { name: "best-day", cycle: 'daily' }
    ],
    features: [{
        name: "kills",
        options: {
            updatePolicy: 'aggregate',
            sortPolicy: 'high-to-low'
        }
    },{
        name: "coins",
        options: {
            updatePolicy: 'aggregate',
            sortPolicy: 'high-to-low'
        }
    }, {
        name: "best-kills",
        options: {
            updatePolicy: 'best',
            sortPolicy: 'high-to-low'
        }
    }, {
        name: "best-time",
        options: {
            updatePolicy: 'best',
            sortPolicy: 'low-to-high'
        }
    }]
});

To update multiples entries in all dimensions you can do it like this:

await mlb.update([{
    id: "player1",
    values: {
        kills: 27,
        coins: 684,
        "best-kills": 27,
        "best-time": 427
    }
}, {
    id: "player2",
    values: {
        kills: 33,
        coins: 719,
        // you can skip features if you want too
        // "best-kills": 33,
        // "best-time": 479
    }
}]);

You can filter which dimensions are updated, just list which dimensions you want to update in an array after the entries:

await mlb.update([ ... ], ["global", "best-month", "best-week", "best-day"]); // skip "us", the listed players are not from the US

What about querying?

await mlb.top("world", "kills", 3);
[
    {
        "id": "player2",   
        "ranks": {
            "world": {     
                "kills": 1,
                "coins": 1 
            },
            "us": {        
                "kills": 1,
                "coins": 1 
            },
            "best-month": {
                "kills": 1,
                "coins": 1
            },
            "best-week": {
                "kills": 1,
                "coins": 1
            },
            "best-day": {
                "kills": 1,
                "coins": 1
            }
        },
        "scores": {
            "world": {
                "kills": 33,
                "coins": 719
            },
            "us": {
                "kills": 33,
                "coins": 719
            },
            "best-month": {
                "kills": 33,
                "coins": 719
            },
            "best-week": {
                "kills": 33,
                "coins": 719
            },
            "best-day": {
                "kills": 33,
                "coins": 719
            }
        }
    },
    ...
]

Woah, thats a lot of data! You can filter queries to specific dimensions/features like so:

await mlb.top("world", "kills", 3, {
    dimensions: ["world"],
    features: ["kills", "coins"]
});
[
    {
        "id": "player2",
        "ranks": {
            "world": { "kills": 1, "coins": 1 }
        },
        "scores": {
            "world": { "kills": 33, "coins": 719 }
        }
    },
    {
        "id": "player1",
        "ranks": {
            "world": { "kills": 2, "coins": 2 }
        },
        "scores": {
            "world": { "kills": 27, "coins": 684 }
        }
    }
]

bottom, list, around, remove and count work like you would expect.

You can access a single leaderboard like so:

mlb.getLeaderboard("best-month", "kills"); // will give you the current leaderboard
mlb.getRawLeaderboard("best-month", "kills"); // will give you the periodic leaderboard wrapper

Showcasing leaderboards

Let's say you have in the front page of your game the daily leaderboard. What happens when the day change and there are no entries? Do you want to show the empty leaderboard? I would fall back to the weekly leaderboard, and if the change also is a week change then to the monthly, then yearly, then permanent.

You can do this easily with the showcase function:

await mlb.showcase(["best-day", "best-week", "best-month", "world"], "kills", 10);

This will query the top threshold entries from the leaderboard that has at least threshold entries in the order you provided. If none match, the last in the order ("world") will be used to query the entries.