config tests added,

.env file support added with dotenv,
README.md file updated for .evn file support,
database lost connection bug crash fixed,
session server run_session long timeout bug fixed

README.md

@@ -1,3 +1,11 @@
 # pixel-streaming-coordinator
 
-pixel streaming coordinator
+pixel streaming coordinator
+
+configure environment variables with .env file
+
+.env:
+
+PORT=
+DATABASE_URL=""
+DATABASE_NAME=""

app.js

@@ -8,6 +8,13 @@ const {request_logger, error_logger} = require('./src/middlewares/logger')
 const {options, cors} = require('./src/middlewares/cors')
 const {error_handler} = require('./src/middlewares/error_handler')
 //const limiter = require('./src/middlewares/limiter')
+const {test_config} = require('./tests/config')
+
+if (!test_config()) {
+    process.exit(1)
+}
+
+console.log('all initial tests successfully passed')
 
 app.options(options)
 
@@ -32,5 +39,4 @@ app.use(error_handler)
 
 // start listen server
 app.listen(port)
-console.log('all config.js tests passed successfully [not developed]')
 console.log(`Listening at http://localhost:${port}`)

config.js

@@ -1,3 +1,5 @@
+require('dotenv').config()
+
 module.exports = {
     port: parseInt(process.env.PORT),
     database_url: process.env.DATABASE_URL,

package.json

@@ -20,8 +20,12 @@
   "dependencies": {
     "body-parser": "^1.20.1",
     "celebrate": "^15.0.1",
+    "dotenv": "^16.0.3",
     "express": "^4.18.2",
     "express-rate-limit": "^6.7.0",
+    "helmet": "^6.0.1",
+    "mongodb": "^4.13.0",
+    "node-datetime": "^2.1.2",
     "request": "^2.88.2"
   }
 }

src/database/database.js

@@ -3,18 +3,21 @@ const { database_url, database_name } = require('../../config')
 const crypto = require("crypto")
 let max_database_connection_timeout = 1000
 
+const client = new MongoClient(database_url, {
+    serverSelectionTimeoutMS: max_database_connection_timeout, 
+    useUnifiedTopology: true
+})
+
 const get_db = async () => {
-    const client = new MongoClient(database_url, {
-        serverSelectionTimeoutMS: max_database_connection_timeout, 
-        useUnifiedTopology: true
-    })
     try {
         await client.connect()
+        await client.db(database_name).command({ ping: 1 })
+        return client.db(database_name)
     } catch (err) {
-        console.log('can not connect to database')
+        console.error('can not connect to database')
+        await client.close()
         return null
     }
-    return client.db(database_name)
 }
 
 const get_titles = async (start, count) => {
@@ -41,14 +44,14 @@ const get_free_session_servers = async (title) => {
     var active_session = db.collection('active_session')
     
     var free_servers = []
-    var servers_length = servers.length
-    for (var i = 0; i < servers_length; ++i) {
-        var sessions = await active_session.find({url:servers[i].url}).toArray()
-        if (servers[i].limit > sessions.length) {
-            free_servers.push(servers[i])
+
+    for (const server of servers) {
+        var sessions = await active_session.find({server_url:server.url}).toArray()
+        if (server.limit > sessions.length) {
+            free_servers.push(server)
         }
     }
-    return free_servers
+    return (free_servers.length) ? free_servers : null
 }
 
 const add_active_session = async (server_url, session_id, websocket_url) => {

src/modules/session_server.js

@@ -1,44 +1,55 @@
 var request = require('request')
 const max_response_timeout = 1000
-const max_run_session_timeout = 10000
+const max_run_session_timeout = 5000
+
+
+const ping_session_server = async (url) => {
+
+    var options = {
+        url: url + '/ping',
+        method: "GET",
+        timeout: max_response_timeout
+    }
+
+    return new Promise(function (resolve, reject) {
+        request(options,
+            async function(err, answer, data) {
+                if (err || answer.statusCode != 200) {
+                    resolve(false)
+                } else {
+                    resolve(true)
+                }
+            }
+        )
+    })
+}
 
 const get_fastest_session_server = async (free_servers) => {
     var fastest_server = null
-    var free_servers_length = free_servers.length
-    
-    for (var i = 0; i < free_servers_length; ++i) {
-        var options = {
-            url: free_servers[i].url + '/ping',
-            method: "GET",
-            timeout: max_response_timeout
+
+    Promise.all(free_servers.map(async (server) => {
+        const is_working = await ping_session_server(server.url)
+        if (is_working) {
+            if (!fastest_server) {
+                fastest_server = server
+            }
         }
-    
-        var f = (async function(server) {
-            request(options,
-                async function(err, answer, data) {
-                    if (err) {
-                        return
-                    }
-                    if (!fastest_server) {
-                        fastest_server = server
-                    }
-                }
-            )
-        })(free_servers[i])
-    }
+    }))
 
     var timeout_count = 0
-    var check_times = 1000
+    var check_times = 100
+
     while (true) {
         ++timeout_count
         if (fastest_server) {
             return fastest_server
         }
         if (timeout_count > check_times) {
-            return fastest_server
+            break
         }
         await new Promise(resolve => setTimeout(resolve, max_response_timeout / check_times))
     }
+    return fastest_server
 }
 
 const run_session = async (server_url, session_id, title) => {

tests/config.js

@@ -0,0 +1,35 @@
+var config = require('../config')
+
+const not_valid = (message) => {
+    console.log('not valid: ', message)
+}
+
+const test_config = () => {
+    var config_pass = true
+
+    if (!config) {
+        not_valid('config')
+        config_pass = false
+    }
+
+    if (!config.port) {
+        not_valid('port')
+        config_pass = false
+    }
+
+    if (!config.database_url) {
+        not_valid('database_url')
+        config_pass = false
+    }
+
+    if (!config.database_name) {
+        not_valid('database_name')
+        config_pass = false
+    }
+
+    return config_pass
+}
+
+module.exports = {
+    test_config
+}