82 lines
2.4 KiB
TypeScript
82 lines
2.4 KiB
TypeScript
import { log, Mutex, redis, TTLCache } from "../deps.ts";
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import config from "./config.ts";
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const KEY_EXPIRY = 3; // seconds
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interface CommentManager {
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getAndIncrement(key: string): Promise<number>;
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}
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class LocalCommentManager implements CommentManager {
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private cache: TTLCache<number>;
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constructor() {
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this.cache = new TTLCache(KEY_EXPIRY * 1000);
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}
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getAndIncrement(key: string): Promise<number> {
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const value = this.cache.get(key) ?? 0;
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this.cache.set(key, value + 1);
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return Promise.resolve(value);
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}
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}
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class RedisCommentManager implements CommentManager {
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private connectOptions: redis.RedisConnectOptions;
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private lock: Mutex;
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private _redis: Promise<redis.Redis> | undefined;
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constructor(options: redis.RedisConnectOptions) {
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this.connectOptions = options;
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this.lock = new Mutex();
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}
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// manual lazy init, redis.createLazyClient currently doesn't support pipelines :/
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private redis(): Promise<redis.Redis> {
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if (!this._redis) {
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this._redis = redis.connect({
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...this.connectOptions,
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maxRetryCount: 3,
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});
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}
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return this._redis;
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}
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async getAndIncrement(key: string): Promise<number> {
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await this.lock.acquire();
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try {
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const redis = await this.redis();
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key = `reviewcomment:${key}`;
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const pl = redis.pipeline();
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pl.incr(key);
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pl.expire(key, KEY_EXPIRY);
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const results = await pl.flush();
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const newValue = results[0] as number;
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return newValue - 1; // return old value
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} finally {
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this.lock.release();
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}
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}
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}
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let commentManager: CommentManager;
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if (config.redisUrl) {
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const opts = redis.parseURL(config.redisUrl);
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// validate perms now to avoid unnecessarily retrying later on
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const host = opts.hostname + (opts.port ? `:${opts.port}` : "");
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const permStatus = await Deno.permissions.request({ name: "net", host: host });
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if (permStatus.state !== "granted") {
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throw new Error("Network access to redis url is required");
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}
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log.debug("using RedisCommentManager");
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commentManager = new RedisCommentManager(opts);
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} else {
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log.debug("using LocalCommentManager, no redis url configured");
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commentManager = new LocalCommentManager();
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}
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export { commentManager };
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