renaming Lock to Mutex and use appConfig

express.js

@@ -71,13 +71,6 @@ function loggedIn(req, res, next) {
   }
 }
 
-//Start and listen on port
-
-
-
-// --- R O U T E S ---
-// when the website is asked to render "/pageName" it will come here and see what are the "instructions" to render said page. If the page isn't here, then the website won't render it properly.
-
 app.use('/', authRouter)
 app.use('/', staticMarkdownRouter)
 app.use('/news', newsRouter)

lib/LeaderboardService.js

@@ -1,8 +1,8 @@
 class LeaderboardService {
-    constructor(cacheService, lockService, leaderboardRepository, lockTimeout = 3000) {
+    constructor(cacheService, mutexService, leaderboardRepository, lockTimeout = 3000) {
         this.lockTimeout = lockTimeout
         this.cacheService = cacheService
-        this.lockService = lockService
+        this.mutexService = mutexService
         this.leaderboardRepository = leaderboardRepository
     }
 
@@ -18,13 +18,13 @@ class LeaderboardService {
             return this.cacheService.get(cacheKey)
         }
 
-        if (this.lockService.locked) {
-            await this.lockService.lock(() => {
+        if (this.mutexService.locked) {
+            await this.mutexService.acquire(() => {
             }, this.lockTimeout)
             return this.getLeaderboard(id)
         }
 
-        await this.lockService.lock(async () => {
+        await this.mutexService.acquire(async () => {
             const result = await this.leaderboardRepository.fetchLeaderboard(id)
             this.cacheService.set(cacheKey, result);
         })

lib/LeaderboardServiceFactory.js

@@ -1,10 +1,10 @@
 const LeaderboardService = require("./LeaderboardService");
 const LeaderboardRepository = require("./LeaderboardRepository");
-const {LockService} = require("./LockService");
+const {MutexService} = require("./MutexService");
 const NodeCache = require("node-cache");
 const {Axios} = require("axios");
 
-const leaderboardLock = new LockService()
+const leaderboardMutex = new MutexService()
 const cacheService = new NodeCache(
     {
         stdTTL: 300, // use 5 min for all caches if not changed with ttl
@@ -19,5 +19,5 @@ module.exports = (javaApiBaseURL, token) => {
     };
     const javaApiClient = new Axios(config)
 
-    return new LeaderboardService(cacheService, leaderboardLock, new LeaderboardRepository(javaApiClient))
+    return new LeaderboardService(cacheService, leaderboardMutex, new LeaderboardRepository(javaApiClient))
 }

lib/LockService.js → lib/MutexService.js

@@ -1,13 +1,13 @@
-class LockoutTimeoutError extends Error {
+class AcquireTimeoutError extends Error {
 }
 
-class LockService {
+class MutexService {
     constructor() {
         this.queue = [];
         this.locked = false;
     }
 
-    async lock(callback, timeLimitMS = 500) {
+    async acquire(callback, timeLimitMS = 500) {
         let timeoutHandle;
         const lockHandler = {}
 
@@ -16,7 +16,7 @@ class LockService {
             lockHandler.reject = reject
 
             timeoutHandle = setTimeout(
-                () => reject(new LockoutTimeoutError('LockService timeout reached')),
+                () => reject(new AcquireTimeoutError('MutexService timeout reached')),
                 timeLimitMS
             );
         });
@@ -66,5 +66,5 @@ class LockService {
     }
 }
 
-module.exports.LockService = LockService
-module.exports.LockoutTimeoutError = LockoutTimeoutError
+module.exports.MutexService = MutexService
+module.exports.AcquireTimeoutError = AcquireTimeoutError

routes/views/leaderboardRouter.js

@@ -1,7 +1,9 @@
 const express = require('express');
 const router = express.Router();
 const LeaderboardServiceFactory = require('../../lib/LeaderboardServiceFactory')
-const {LockoutTimeoutError} = require("../../lib/LockService");
+const {AcquireTimeoutError} = require('../../lib/MutexService');
+const appConfig = require('../../config/app')
+
 
 const getLeaderboardId = (leaderboardName) => {
     const mapping = {
@@ -39,11 +41,11 @@ router.get('/:leaderboard.json', async (req, res) => {
         }
 
         const token = req.user.data.attributes.token
-        const leaderboardService = LeaderboardServiceFactory(process.env.API_URL, token)
+        const leaderboardService = LeaderboardServiceFactory(appConfig.apiUrl, token)
 
         return res.json(await leaderboardService.getLeaderboard(leaderboardId))
     } catch (e) {
-        if (e instanceof LockoutTimeoutError) {
+        if (e instanceof AcquireTimeoutError) {
             return res.status(503).json({error: 'timeout reached'})
         }
 

tests/LeaderboardService.test.js

@@ -1,6 +1,6 @@
 const LeaderboardService = require("../lib/LeaderboardService")
 const LeaderboardRepository = require("../lib/LeaderboardRepository")
-const {LockService} = require("../lib/LockService")
+const {MutexService} = require("../lib/MutexService")
 const NodeCache = require("node-cache")
 const {Axios} = require("axios");
 
@@ -34,7 +34,7 @@ beforeEach(() => {
         new NodeCache(
             { stdTTL: 300, checkperiod: 600 }
         ),
-        new LockService(),
+        new MutexService(),
         new LeaderboardRepository(axios)
     )
 })
@@ -97,9 +97,9 @@ test('timeout for cache creation throws an error', async () => {
     expect.assertions(1);
     axios.get.mockImplementationOnce(() => Promise.resolve({ status: 200, data: fakeEntry }))
 
-    leaderboardService.lockService.locked = true
+    leaderboardService.mutexService.locked = true
     leaderboardService.getLeaderboard(0).then(() => {}).catch((e) => {
-        expect(e.toString()).toBe('Error: LockService timeout reached')
+        expect(e.toString()).toBe('Error: MutexService timeout reached')
     })
 
     jest.runOnlyPendingTimers()

tests/MutexService.test.js

@@ -0,0 +1,61 @@
+const {AcquireTimeoutError, MutexService} = require('../lib/MutexService')
+test('release will unlock the queue', async () => {
+    const mutexService = new MutexService()
+    expect(mutexService.locked).toBe(false)
+
+    await mutexService.acquire(() => {
+        expect(mutexService.locked).toBe(true)
+    })
+
+    expect(mutexService.locked).toBe(false)
+})
+
+test('call lock twice will fill the queue', async () => {
+    let oneCalled = false
+    let twoCalled = false
+    const mutexService = new MutexService()
+    const one = mutexService.acquire(() => oneCalled = true)
+    const two = mutexService.acquire(() =>  twoCalled = true)
+
+    expect(mutexService.queue).toHaveLength(1)
+    expect(mutexService.locked).toBe(true)
+
+    await one
+    await two
+    expect(oneCalled).toBe(true)
+    expect(twoCalled).toBe(true)
+    expect(mutexService.queue).toHaveLength(0)
+    expect(mutexService.locked).toBe(false)
+})
+
+test('lock timeout will trow an error if locked by another "process" for too long', async () => {
+    expect.assertions(1);
+
+    const mutexService = new MutexService()
+
+    await mutexService.acquire(async () => {
+        try {
+            await mutexService.acquire(() => {}, 1)
+        } catch (e) {
+            expect(e).toBeInstanceOf(AcquireTimeoutError)
+        }
+    })
+});
+
+test('lock timeout will remove it from queue', async () => {
+    expect.assertions(2);
+
+    const mutexService = new MutexService()
+
+    await mutexService.acquire(async () => {
+        try {
+            await mutexService.acquire(() => {
+            }, 1)
+        } catch (e) {
+            expect(e).toBeInstanceOf(AcquireTimeoutError)
+            expect(mutexService.queue).toHaveLength(0);
+        }
+
+    })
+})
+