From: Luigi Pinca <luigipinca@gmail.com>
Date: Sun, 7 Apr 2013 08:48:10 +0000 (+0200)
Subject: use a PRNG based on `crypto.randomBytes` to play tracks randomly
X-Git-Url: https://git.saalbach.dev/?a=commitdiff_plain;h=30cec4c;p=binbsis50.git

use a PRNG based on `crypto.randomBytes` to play tracks randomly
---

diff --git a/lib/prng.js b/lib/prng.js
new file mode 100644
index 0000000..be9cc80
--- /dev/null
+++ b/lib/prng.js
@@ -0,0 +1,30 @@
+/**
+ * Module dependencies.
+ */
+
+var crypto = require('crypto')
+  , rrange = 4294967296;
+
+/**
+ * Return an integer, pseudo-random number in the range [0, 2^32).
+ */
+
+var nextInt = function() {
+  return crypto.randomBytes(4).readUInt32BE(0);
+};
+
+/**
+ * Return a floating-point, pseudo-random number in the range [0, 1).
+ */
+
+var rand = function() {
+  return nextInt() / rrange;
+};
+
+/**
+ * Return an integer, pseudo-random number in the range [0, max).
+ */
+
+exports.randInt = function(max) {
+  return Math.floor(rand() * max);
+};
diff --git a/lib/room.js b/lib/room.js
index 9ea7d88..ab5ebf5 100644
--- a/lib/room.js
+++ b/lib/room.js
@@ -8,10 +8,13 @@ var amatch = require('./match')
   , config = require('../config')
   , fifolength = config.songsinarun * config.gameswithnorepeats
   , io
-  , isUsername = require('./utils').isUsername
+  , randInt = require('./prng').randInt
   , sockets
   , songsdb = clients.songs
-  , usersdb = clients.users;
+  , usersdb = clients.users
+  , utils = require('./utils')
+  , isUsername = utils.isUsername
+  , trackscount = utils.trackscount;
 
 /**
  * Expose the constructor.
@@ -42,7 +45,6 @@ function Room(roomname) {
     , status
     , title // Title in lowercase
     , trackName
-    , trackscount = 0
     , trackViewUrl
     , totusers = 0
     , usersData = Object.create(null);
@@ -135,7 +137,7 @@ function Room(roomname) {
     totusers++;
     // Broadcast new user event
     io.sockets.emit('updateoverview', roomname, totusers);
-    socket.emit('ready', usersData, trackscount, loggedin);
+    socket.emit('ready', usersData, trackscount[roomname], loggedin);
     socket.broadcast.to(roomname).emit('newuser', socket.nickname, usersData);
   };
 
@@ -331,7 +333,8 @@ function Room(roomname) {
 
   // Extract a random track from the database and send the load event
   var sendLoadTrack = function() {
-    songsdb.srandmember(roomname, function(err, res) {
+    var index = randInt(trackscount[roomname]);
+    songsdb.zrange(roomname, index, index, function(err, res) {
       // Check if extracted track is in the list of already played tracks
       if (~playedtracks.indexOf(res)) {
         return sendLoadTrack();
@@ -451,10 +454,10 @@ function Room(roomname) {
 
   // Start the room
   this.start = function() {
-    songsdb.scard(roomname, function(err, res) {
-      trackscount = res;
+    songsdb.zcard(roomname, function(err, card) {
+      trackscount[roomname] = card;
+      sendLoadTrack();
     });
-    sendLoadTrack();
   };
 
   this.unignore = function(who, executor) {
diff --git a/lib/utils.js b/lib/utils.js
index 367e601..d806a4f 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -39,6 +39,12 @@ exports.britishFormat = function(date) {
   return day+'/'+month+'/'+year;
 };
 
+/**
+ * Helper object for faster and easier access to rooms' cardinalities (number of tracks).
+ */
+
+exports.trackscount = {};
+
 /**
  * Check whether a given string is a valid email address.
  */
diff --git a/package.json b/package.json
index c6aa8f7..18733e8 100644
--- a/package.json
+++ b/package.json
@@ -7,14 +7,14 @@
     "async": "0.2.x",
     "canvas": "0.13.x",
     "connect-redis": "1.4.x",
-    "express": "3.x",
+    "express": "3.1.x",
     "jade": "0.28.x",
     "nodemailer": "0.3.x",
     "redis": "0.7.x",
     "socket.io": "0.9.x"
   },
   "devDependencies": {
-    "JSONStream": "0.4.x"
+    "JSONStream": "0.6.x"
   },
   "engines": {
     "node": "0.8.x"
@@ -24,5 +24,5 @@
     "start": "node app.js"
   },
   "subdomain": "binb",
-  "version": "0.3.5-14"
+  "version": "0.3.5-15"
 }
diff --git a/routes/site.js b/routes/site.js
index 6e91359..42d4177 100644
--- a/routes/site.js
+++ b/routes/site.js
@@ -5,8 +5,11 @@
 var async = require('async')
   , Captcha = require('../lib/captcha')
   , db = require('../lib/redis-clients').songs
-  , randomSlogan = require('../lib/utils').randomSlogan
-  , rooms = require('../config').rooms;
+  , randInt = require('../lib/prng').randInt
+  , rooms = require('../config').rooms
+  , utils = require('../lib/utils')
+  , randomSlogan = utils.randomSlogan
+  , trackscount = utils.trackscount;
 
 /**
  * Generate a task.
@@ -14,7 +17,8 @@ var async = require('async')
 
 var task = function(genre) {
   return function(callback) {
-    db.srandmember(genre, function(err, res) {
+    var index = randInt(trackscount[genre]);
+    db.zrange(genre, index, index, function(err, res) {
       db.hget('song:'+res, 'artworkUrl100', callback);
     });
   };
diff --git a/util/load_sample_tracks.js b/util/load_sample_tracks.js
index 54f3ada..dabac87 100644
--- a/util/load_sample_tracks.js
+++ b/util/load_sample_tracks.js
@@ -12,6 +12,7 @@ var artistIds = require('./artist-ids')
   , rc = require('redis').createClient()
   , rockIds = artistIds.rock
   , rooms = require('../config').rooms
+  , score
   , skip = 0 // Skip counter
   , songId = 0;
 
@@ -29,6 +30,7 @@ var options = {
 
 var updateRooms = function(artistId) {
   rooms = ['mixed'];
+  score = 0;
   if (artistId === popIds[0]) {
     rooms.push('hits', 'pop');
     // Set the skip counter (there is no need to update the rooms for the next pop artists)
@@ -64,9 +66,11 @@ parser.on('data', function(track) {
   );
 
   rooms.forEach(function(room) {
-    rc.sadd(room, songId);
+    var _score = (room === 'mixed') ? songId : score;
+    rc.zadd(room, _score, songId);
   });
 
+  score++;
   songId++;
 });