Zaid Abdulla
d787f66e3f
Because the hostInfo MongoDB command may not be allowed in some environments. Also, in sharded deployments the clock skew may differ between different shards so using hostInfo is not enough. This new implementation simply assumes the clocks are in sync within a certain range and throws an error if clocks are found to be out of sync.
119 lines
3.2 KiB
TypeScript
119 lines
3.2 KiB
TypeScript
/**
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* Copyright 2013-2019 GenieACS Inc.
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*
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* This file is part of GenieACS.
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*
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* GenieACS is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* GenieACS is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with GenieACS. If not, see <http://www.gnu.org/licenses/>.
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*/
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import { Collection } from "mongodb";
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import { onConnect } from "./db";
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import * as config from "./config";
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const CLOCK_SKEW_TOLERANCE = 30000;
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const MAX_CACHE_TTL = +config.get("MAX_CACHE_TTL");
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let cacheCollection: Collection;
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onConnect(async (db) => {
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cacheCollection = db.collection("cache");
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await cacheCollection.createIndex({ expire: 1 }, { expireAfterSeconds: 0 });
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});
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export async function get(key: string): Promise<string> {
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const res = await cacheCollection.findOne({ _id: key });
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if (res) return res["value"];
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return null;
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}
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export async function del(key: string): Promise<void> {
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await cacheCollection.deleteOne({ _id: key });
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}
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export async function set(
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key: string,
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value: string,
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ttl: number = MAX_CACHE_TTL
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): Promise<void> {
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const timestamp = new Date();
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const expire = new Date(
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timestamp.getTime() + CLOCK_SKEW_TOLERANCE + ttl * 1000
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);
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await cacheCollection.replaceOne(
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{ _id: key },
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{ _id: key, value, expire, timestamp },
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{ upsert: true }
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);
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}
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export async function pop(key: string): Promise<any> {
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const res = await cacheCollection.findOneAndDelete({ _id: key });
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if (res && res["value"]) return res["value"]["value"];
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return null;
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}
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export async function acquireLock(
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lockName: string,
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ttl: number,
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timeout = 0,
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token = Math.random().toString(36).slice(2)
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): Promise<string> {
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try {
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const now = Date.now();
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const r = await cacheCollection.findOneAndUpdate(
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{ _id: lockName, token },
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{
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$set: {
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value: token,
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expire: new Date(now + ttl + CLOCK_SKEW_TOLERANCE),
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},
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$currentDate: { timestamp: true },
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},
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{ upsert: true, returnOriginal: false }
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);
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const v = r.value;
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if (Math.abs(v["timestamp"].getTime() - now) > CLOCK_SKEW_TOLERANCE)
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throw new Error("Database clock skew too great");
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} catch (err) {
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if (err.code === 11000) {
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if (timeout > 0) {
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return new Promise((resolve, reject) => {
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const w = 50 + Math.random() * 50;
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setTimeout(() => {
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acquireLock(lockName, ttl, timeout - w, token).then(
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resolve,
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reject
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);
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}, w);
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});
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}
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throw new Error("Failed to acquire lock");
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}
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throw err;
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}
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return token;
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}
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export async function releaseLock(
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lockName: string,
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token: string
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): Promise<void> {
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const res = await cacheCollection.deleteOne({
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_id: lockName,
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value: token,
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});
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if (res["result"]["n"] !== 1) throw new Error("Lock expired");
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}
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