`/api/games/user` – nondeterministic, returning duplicates, missing results

[matthew-piziak]

Endpoint under test:

curl https://lichess.org/api/games/user/Deltaway?rated=true&since=1709269200000&perfType=blitz -H "Authorization: <TOKEN_REDACTED>" -H "Accept: application/x-ndjson"

In restclient format, for clarity:

GET https://lichess.org/api/games/user/Deltaway?rated=true&since=1709269200000&perfType=blitz
Authorization: Bearer <TOKEN_REDACTED>
Accept: application/x-ndjson

I expect slightly over 500 games returned, but I get back 900–1500 objects (the number varies with each run). Many of these are duplicates, for example I got five of game I0iDZ1UZ returned in the results. And when I filter out duplicates on my end I'm missing some games that I ought to see based on the results of game search on the web UI.

It's possible I'm misunderstanding correct usage of the API—sorry if so!

[matthew-piziak]

By removing the perfType query argument and filtering the stream locally, the correct results are produced (currently 519 games).

Recently GameApiV2.scala was updated at this line, which turns on ElasticSearch when a perfKey argument is included in the query. The change deployed at approximately the time I noticed the breakage, so there might be a connection there.

[khgiddon]

+1: My app (Chess Stamps) using the /games API was broken at approximately the same time as the deploy that @matthew-piziak pointed out. All of my API calls are returning no results but also seem to be working correctly when excluding the perfKey argument.

[matthew-piziak]

Interesting @khgiddon, in my case I do get results but they're the wrong ones. Still, there's the common implication of perfKey which makes me think the secondary database is the cause.

Thankfully I don't have many games and my usecase is very simple. So my workaround is simple too. I just pull all my games regardless of perfKey and filter them myself.

(ns chess
    (:require
     [clojure.pprint :as pp]
     [clojure.string :as s]
     [clojure.java.io :as io]
     [clj-http.client :as client]
     [cheshire.core :as json]
     [clj-time.core :as t]
     [clj-time.coerce :as tc]))

(defn game->rating [game]
  (let [{{:keys [white black]} :players} game]
    (:rating (case (-> white :user :name) "Deltaway" white black))))

(defn game->date [game]
  (->> game :createdAt tc/from-long ((juxt t/year t/month t/day)) (apply t/local-date) str))

(defn game-desired? [game]
  (= "blitz" (:speed game)))

(def process-games
  (comp
   (map #(json/parse-string-strict % true))
   (filter game-desired?)
   (map #(str (game->date %) "," (game->rating %) "\n"))))

(defn download-ratings []
  (let [url (str "https://lichess.org/api/games/user/Deltaway?rated=true&since=1709269200000&sort=dateAsc")
        headers {"Authorization" "Bearer <TOKEN_REDACTED>" "Accept" "application/x-ndjson"}
        response (client/get url {:headers headers :as :reader})]
    (with-open [reader (:body response)
                writer (io/writer "ratings.csv")]
      (.write writer "date,rating\n")
      (doseq [line (sequence process-games (line-seq reader))] (.write writer line)))))

(download-ratings)