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Fix ladder double-update issue
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Caused by smogon#8015 incorrectly copy/pasting only parts of smogon#7960.

I also cleaned up the ladder fast-update code while I was working
on this.
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@Zarel @Quanyails
Zarel authored and Quanyails committed May 12, 2021
1 parent 7a44f2d commit e4f67ee
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Showing 2 changed files with 52 additions and 72 deletions.
56 changes: 32 additions & 24 deletions server/ladders-local.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -171,30 +171,7 @@ export class LadderStore {
updateRow(row: LadderRow, score: number, foeElo: number) {
let elo = row[1];

// The K factor determines how much your Elo changes when you win or
// lose games. Larger K means more change.
// In the "original" Elo, K is constant, but it's common for K to
// get smaller as your rating goes up
let K = 50;

// dynamic K-scaling (optional)
if (elo < 1200) {
if (score < 0.5) {
K = 10 + (elo - 1000) * 40 / 200;
} else if (score > 0.5) {
K = 90 - (elo - 1000) * 40 / 200;
}
} else if (elo > 1350 && elo <= 1600) {
K = 40;
} else {
K = 32;
}

// main Elo formula
const E = 1 / (1 + Math.pow(10, (foeElo - elo) / 400));
elo += K * (score - E);

if (elo < 1000) elo = 1000;
elo = this.calculateElo(elo, score, foeElo);

row[1] = elo;
if (score > 0.6) {
Expand Down Expand Up @@ -321,6 +298,37 @@ export class LadderStore {
return `${output}<td>${ratings[3]}</td><td>${ratings[4]}</td><td>${ratings[3] + ratings[4]}</td></tr>`;
}

/**
* Calculates Elo based on a match result
*/
calculateElo(oldElo: number, score: number, foeElo: number): number {
// The K factor determines how much your Elo changes when you win or
// lose games. Larger K means more change.
// In the "original" Elo, K is constant, but it's common for K to
// get smaller as your rating goes up
let K = 50;

// dynamic K-scaling (optional)
if (oldElo < 1200) {
if (score < 0.5) {
K = 10 + (oldElo - 1000) * 40 / 200;
} else if (score > 0.5) {
K = 90 - (oldElo - 1000) * 40 / 200;
}
} else if (oldElo > 1350 && oldElo <= 1600) {
K = 40;
} else {
K = 32;
}

// main Elo formula
const E = 1 / (1 + Math.pow(10, (foeElo - oldElo) / 400));

const newElo = oldElo + K * (score - E);

return Math.max(newElo, 1000);
}

/**
* Returns a Promise for an array of strings of <tr>s for ladder ratings of the user
*/
Expand Down
68 changes: 20 additions & 48 deletions server/ladders-remote.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,9 @@ export class LadderStore {
* Update the Elo rating for two players after a battle, and display
* the results in the passed room.
*/
async updateRating(p1name: string, p2name: string, p1score: number, room: AnyObject) {
async updateRating(p1name: string, p2name: string, p1score: number, room: AnyObject): Promise<[
number, AnyObject | undefined | null, AnyObject | undefined | null,
]> {
if (Ladders.disabled) {
room.addRaw(`Ratings not updated. The ladders are currently disabled.`).update();
return [p1score, null, null];
Expand Down Expand Up @@ -101,18 +103,16 @@ export class LadderStore {
if (p2) p2.mmrCache[formatid] = +p2NewElo;

room.update();

const [data, error] = await ladderUpdatePromise;
let problem = false;

let problem = false;
if (error) {
if (error.message === 'stream interrupt') {
room.add(`||Ladder updated, but score could not be retrieved.`);
} else {
room.add(`||Ladder (probably) updated, but score could not be retrieved (${error.message}).`);
if (error.message !== 'stream interrupt') {
room.add(`||Ladder isn't responding, score probably updated but might not have (${error.message}).`);
problem = true;
}
problem = true;
} else if (!room.battle) {
Monitor.warn(`room expired before ladder update was received`);
problem = true;
} else if (!data) {
room.add(`|error|Unexpected response ${data} from ladder server.`);
Expand All @@ -132,37 +132,7 @@ export class LadderStore {
return [p1score, null, null];
}

let p1rating;
let p2rating;
try {
p1rating = data!.p1rating;
p2rating = data!.p2rating;

let oldelo = Math.round(p1rating.oldelo);
let elo = Math.round(p1rating.elo);
let act = (p1score > 0.9 ? `winning` : (p1score < 0.1 ? `losing` : `tying`));
let reasons = `${elo - oldelo} for ${act}`;
if (!reasons.startsWith('-')) reasons = '+' + reasons;
room.addRaw(Utils.html`${p1name}'s rating: ${oldelo} &rarr; <strong>${elo}</strong><br />(${reasons})`);
let minElo = elo;

oldelo = Math.round(p2rating.oldelo);
elo = Math.round(p2rating.elo);
act = (p1score > 0.9 || p1score < 0 ? `losing` : (p1score < 0.1 ? `winning` : `tying`));
reasons = `${elo - oldelo} for ${act}`;
if (!reasons.startsWith('-')) reasons = '+' + reasons;
room.addRaw(Utils.html`${p2name}'s rating: ${oldelo} &rarr; <strong>${elo}</strong><br />(${reasons})`);
if (elo < minElo) minElo = elo;
room.rated = minElo;

if (p1) p1.mmrCache[formatid] = +p1rating.elo;
if (p2) p2.mmrCache[formatid] = +p2rating.elo;
room.update();
} catch (e) {
room.addRaw(`There was an error calculating rating changes.`);
room.update();
}
return [p1score, p1rating, p2rating];
return [p1score, data?.p1rating, data?.p2rating];
}

/**
Expand All @@ -175,31 +145,33 @@ export class LadderStore {
}
/**
* Calculates Elo based on a match result
*
*/
private calculateElo(previousUserElo: number, score: number, foeElo: number): number {
calculateElo(oldElo: number, score: number, foeElo: number): number {
// see lib/ntbb-ladder.lib.php in the pokemon-showdown-client repo for the login server implementation
// *intentionally* different from calculation in ladders-local, due to the high activity on the main server

// The K factor determines how much your Elo changes when you win or
// lose games. Larger K means more change.
// In the "original" Elo, K is constant, but it's common for K to
// get smaller as your rating goes up
let K = 50;

// dynamic K-scaling (optional)
if (previousUserElo < 1200) {
if (oldElo < 1100) {
if (score < 0.5) {
K = 10 + (previousUserElo - 1000) * 40 / 200;
K = 20 + (oldElo - 1000) * 30 / 100;
} else if (score > 0.5) {
K = 90 - (previousUserElo - 1000) * 40 / 200;
K = 80 - (oldElo - 1000) * 30 / 100;
}
} else if (previousUserElo > 1350 && previousUserElo <= 1600) {
} else if (oldElo > 1300) {
K = 40;
} else {
K = 32;
}

// main Elo formula
const E = 1 / (1 + Math.pow(10, (foeElo - previousUserElo) / 400));
const E = 1 / (1 + Math.pow(10, (foeElo - oldElo) / 400));

const newElo = previousUserElo + K * (score - E);
const newElo = oldElo + K * (score - E);

return Math.max(newElo, 1000);
}
Expand Down

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