Alter channel unload behavior, add additional checks

- Should prevent "write after end" errors caused by unloading a channel before it finishes loading
- Might prevent strange cases of playlists gone wild

changelog

@@ -1,3 +1,15 @@
+Sun Sep  8 17:41 2013 CDT
+    * lib/server.js: Change behavior of unloadChannel - deletes all object
+      keys in the channel object and then sets channel.dead = true
+    * lib/channel.js: Add extra checks in callbacks to ensure certain things
+      don't happen if the channel is dead
+    * lib/playlist.js: Add extra checks to kill the playlist if the channel
+      it is associated with is dead
+    * lib/database.js: Add extra checks to prevent loading channel data into
+      a dead channel object
+    * tests/fastQuit.js: A simple script to open a connection, join a
+      channel, and disconnect immediately to test for race conditions
+
 Sat Sep  7 23:38 2013 CDT
     * lib/user.js: Add "loggingIn" field to act as a lock on async logins.
       Delay further login attempts until the current login attempt finishes.

lib/channel.js

@@ -119,8 +119,12 @@ var Channel = function(name, Server) {
         self.ipkey += "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"[parseInt(Math.random() * 65)]
     }
 
-    Server.db.loadChannelData(self, function () {
-        self.dbloaded = true;
+    Server.db.loadChannelData(self, function (err) {
+        if (err && err === "channel_dead")
+                return;
+        else if (!err || err === "channel_unregistered")
+            self.dbloaded = true;
+
         if(self.registered) {
             self.loadDump();
         }
@@ -150,6 +154,9 @@ Channel.prototype.loadDump = function() {
         return;
     fs.stat(path.join(__dirname, "../chandump", self.name),
             function (err, stats) {
+        if (self.dead)
+            return;
+
         if(!err) {
             var mb = stats.size / 1048576;
             mb = parseInt(mb * 100) / 100;
@@ -165,6 +172,9 @@ Channel.prototype.loadDump = function() {
         }
         fs.readFile(path.join(__dirname, "../chandump", self.name),
                     function(err, data) {
+            if (self.dead)
+                return;
+
             if(err) {
                 if(err.code == "ENOENT") {
                     Logger.errlog.log("WARN: missing dump for " + self.name);

lib/database.js

@@ -405,7 +405,12 @@ Database.prototype.loadChannelData = function (chan, callback) {
         }
 
         if(res.length == 0) {
-            callback("Channel is unregistered", null);
+            callback("channel_unregistered", null);
+            return;
+        }
+
+        if (chan.dead) {
+            callback("channel_dead", null);
             return;
         }
 
@@ -416,6 +421,11 @@ Database.prototype.loadChannelData = function (chan, callback) {
         // Load bans
         query = "SELECT * FROM `chan_" + chan.name + "_bans`";
         self.query(query, function (err, res) {
+            if (chan.dead) {
+                callback("channel_dead", null);
+                return;
+            }
+
             if(err) {
                 callback(err, null);
                 return;

lib/playlist.js

@@ -59,14 +59,26 @@ function Playlist(chan) {
     this.server = chan.server;
     var pl = this;
     this.on("mediaUpdate", function(m) {
+        if (chan.dead) {
+            pl.die();
+            return;
+        }
         chan.sendAll("mediaUpdate", m.timeupdate());
     });
     this.on("changeMedia", function(m) {
+        if (chan.dead) {
+            pl.die();
+            return;
+        }
         chan.onVideoChange();
         chan.sendAll("setCurrent", pl.current.uid);
         chan.sendAll("changeMedia", m.fullupdate());
     });
     this.on("remove", function(item) {
+        if (chan.dead) {
+            pl.die();
+            return;
+        }
         chan.broadcastPlaylistMeta();
         chan.sendAll("delete", {
             uid: item.uid

lib/server.js

@@ -62,8 +62,11 @@ var Server = {
                 break;
             }
         }
-        chan.name = "";
-        chan.canonical_name = "";
+        var keys = Object.keys(chan);
+        for (var i in keys) {
+            delete chan[keys[i]];
+        }
+        chan.dead = true;
     },
     stats: null,
     app: null,

tests/fastQuit.js

@@ -0,0 +1,9 @@
+var io = require('socket.io-client');
+
+var socket = io.connect('http://localhost:1337');
+
+// connect, join a room, then disconnect as quickly as possible
+socket.on('connect', function () {
+    socket.emit('joinChannel', { name: 'test' });
+    socket.disconnect();
+});