Change mempools summary graph to show values (#12349)

* Change mempools summary graph to show values
put swap on the negative axis
fix swap classification

* fix whitespace

* fix incorrect class
fix rrd rename logic

* Style

* missed one

app/Observers/ModuleModelObserver.php

@@ -0,0 +1,69 @@
+<?php
+/*
+ * ModuleModelObserver.php
+ *
+ * Displays +,-,U,. while running discovery and adding,deleting,updating, and doing nothing.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @link       http://librenms.org
+ * @copyright  2020 Tony Murray
+ * @author     Tony Murray <murraytony@gmail.com>
+ */
+
+namespace App\Observers;
+
+use Illuminate\Database\Eloquent\Model as Eloquent;
+
+class ModuleModelObserver
+{
+    /**
+     * Install observers to output +, -, U for models being created, deleted, and updated
+     *
+     * @param string|\Illuminate\Database\Eloquent\Model $model The model name including namespace
+     */
+    public static function observe($model)
+    {
+        static $observed_models = []; // keep track of observed models so we don't duplicate output
+        $class = ltrim($model, '\\');
+
+        if (! in_array($class, $observed_models)) {
+            $model::observe(new ModuleModelObserver());
+            $observed_models[] = $class;
+        }
+    }
+
+    public function saving(Eloquent $model)
+    {
+        if (! $model->isDirty()) {
+            echo '.';
+        }
+    }
+
+    public function updated(Eloquent $model)
+    {
+        d_echo('Updated data:', 'U');
+        d_echo($model->getDirty());
+    }
+
+    public function created(Eloquent $model)
+    {
+        echo '+';
+    }
+
+    public function deleted(Eloquent $model)
+    {
+        echo '-';
+    }
+}