Warn moderators when a channel exceeds size limit

When the chandump is saved, the size of the file is checked.  If it is over the limit, moderators are displayed a message indicating that the channel is too large and they should remove extra playlist items, filters, and/or emotes.

This is a partial solution for #421.

lib/channel/channel.js

@@ -9,6 +9,8 @@ var path = require("path");
 var sio = require("socket.io");
 var db = require("../database");
 
+const SIZE_LIMIT = 1048576;
+
 /**
  * Previously, async channel functions were riddled with race conditions due to
  * an event causing the channel to be unloaded while a pending callback still
@@ -130,6 +132,23 @@ Channel.prototype.initModules = function () {
     self.logger.log("[init] Loaded modules: " + inited.join(", "));
 };
 
+Channel.prototype.getDiskSize = function (cb) {
+    if (this._getDiskSizeTimeout > Date.now()) {
+        return cb(null, this._cachedDiskSize);
+    }
+
+    var self = this;
+    var file = path.join(__dirname, "..", "..", "chandump", self.uniqueName);
+    fs.stat(file, function (err, stats) {
+        if (err) {
+            return cb(err);
+        }
+
+        self._cachedDiskSize = stats.size;
+        cb(null, self._cachedDiskSize);
+    });
+};
+
 Channel.prototype.loadState = function () {
     var self = this;
     var file = path.join(__dirname, "..", "..", "chandump", self.uniqueName);
@@ -158,7 +177,7 @@ Channel.prototype.loadState = function () {
         if (!err) {
             var mb = stats.size / 1048576;
             mb = Math.floor(mb * 100) / 100;
-            if (mb > 1) {
+            if (mb > SIZE_LIMIT / 1048576) {
                 Logger.errlog.log("Large chandump detected: " + self.uniqueName +
                                   " (" + mb + " MiB)");
                 var msg = "This channel's state size has exceeded the memory limit " +
@@ -233,6 +252,20 @@ Channel.prototype.saveState = function () {
      * channels.
      */
     var err = fs.writeFileSync(file, json);
+
+    // Check for large chandump and warn moderators/admins
+    self.getDiskSize(function (err, size) {
+        if (!err && size > SIZE_LIMIT && self.users) {
+            self.users.forEach(function (u) {
+                if (u.account.effectiveRank >= 2) {
+                    u.socket.emit("warnLargeChandump", {
+                        limit: SIZE_LIMIT,
+                        actual: size
+                    });
+                }
+            });
+        }
+    });
 };
 
 Channel.prototype.checkModules = function (fn, args, cb) {

www/js/callbacks.js

@@ -1072,6 +1072,28 @@ Callbacks = {
             row.hide("fade", row.remove.bind(row));
             CHANNEL.emotes.splice(i, 1);
         }
+    },
+
+    warnLargeChandump: function (data) {
+        function toHumanReadable(size) {
+            if (size > 1048576) {
+                return Math.floor((size / 1048576) * 100) / 100 + "MiB";
+            } else if (size > 1024) {
+                return Math.floor((size / 1024) * 100) / 100 + "KiB";
+            } else {
+                return size + "B";
+            }
+        }
+
+        if ($("#chandumptoobig").length > 0) {
+            $("#chandumptoobig").remove();
+        }
+
+        errDialog("This channel currently exceeds the maximum size of " +
+            toHumanReadable(data.limit) + " (channel size is " +
+            toHumanReadable(data.actual) + ").  Please reduce the size by removing " +
+            "unneeded playlist items, filters, and/or emotes or else the channel will " +
+            "be unable to load the next time it is reloaded").attr("id", "chandumptoobig");
     }
 }