Fix bug causing channels to get stuck when DB is down

package.json

@@ -2,7 +2,7 @@
   "author": "Calvin Montgomery",
   "name": "CyTube",
   "description": "Online media synchronizer and chat",
-  "version": "3.21.1",
+  "version": "3.21.2",
   "repository": {
     "url": "http://github.com/calzoneman/sync"
   },

src/channel/channel.js

@@ -90,6 +90,10 @@ function Channel(name) {
     var self = this;
     db.channels.load(this, function (err) {
         if (err && err !== "Channel is not registered") {
+            self.emit("loadFail", "Failed to load channel data from the database");
+            // Force channel to be unloaded, so that it will load properly when
+            // the database connection comes back
+            self.emit("empty");
             return;
         } else {
             self.initModules();

src/server.js

@@ -225,7 +225,9 @@ Server.prototype.unloadChannel = function (chan) {
         return;
     }
 
-    chan.saveState();
+    chan.saveState().catch(error => {
+        Logger.errlog.log(`Failed to save /r/${chan.name} for unload: ${error.stack}`);
+    });
 
     chan.logger.log("[init] Channel shutting down");
     chan.logger.close();
@@ -358,6 +360,9 @@ Server.prototype.reloadPartitionMap = function () {
                     }
                 });
                 this.unloadChannel(channel);
+            }).catch(error => {
+                Logger.errlog.log(`Failed to unload /r/${channel.name} for ` +
+                                  `partition map flip: ${error.stack}`);
             });
         }
     }, 0).then(() => {

src/user.js

@@ -67,6 +67,16 @@ function User(socket) {
                 });
                 return;
             }
+
+            if (!chan.is(Flags.C_READY)) {
+                chan.once("loadFail", reason => {
+                    self.socket.emit("errorMsg", {
+                        msg: reason,
+                        alert: true
+                    });
+                    self.kick(`Channel could not be loaded: ${reason}`);
+                });
+            }
             chan.joinUser(self, data);
         });
     });