Support multiple daily process locking backends with distributed poll…

…ing (librenms#11896)

* Implement locks in the file cache

* Replace custom locks

* implement restore lock
Used when re-hydrating

* remove legacy use statements

* Add class descriptions

* Fix style

* Default to database cache driver

* missed cache_locks table
prevent chicken-egg issue

* style fixes

* Remove custom file lock implementation

* missed items from file cache

* Update schema definition
hmm, other schema noise must be from manual modification as this is generated from a freshly migrated db.

* require predis, it is pure python, so no harm in adding

* and set predis as the default client

alerts.php

@@ -28,32 +28,30 @@
  */
 
 use LibreNMS\Alert\RunAlerts;
-use LibreNMS\Util\FileLock;
 
 $init_modules = ['alerts', 'laravel'];
 require __DIR__ . '/includes/init.php';
 
 $options = getopt('d::');
 
-$alerts_lock = FileLock::lockOrDie('alerts');
-
-$alerts = new RunAlerts();
-
 if (set_debug(isset($options['d']))) {
     echo "DEBUG!\n";
 }
 
-if (! defined('TEST') && \LibreNMS\Config::get('alert.disable') != 'true') {
-    echo 'Start: ' . date('r') . "\r\n";
-    echo 'ClearStaleAlerts():' . PHP_EOL;
-    $alerts->clearStaleAlerts();
-    echo "RunFollowUp():\r\n";
-    $alerts->runFollowUp();
-    echo "RunAlerts():\r\n";
-    $alerts->runAlerts();
-    echo "RunAcks():\r\n";
-    $alerts->runAcks();
-    echo 'End  : ' . date('r') . "\r\n";
+$alerts_lock = Cache::lock('alerts');
+if ($alerts_lock->get()) {
+    $alerts = new RunAlerts();
+    if (! defined('TEST') && \LibreNMS\Config::get('alert.disable') != 'true') {
+        echo 'Start: ' . date('r') . "\r\n";
+        echo 'ClearStaleAlerts():' . PHP_EOL;
+        $alerts->clearStaleAlerts();
+        echo "RunFollowUp():\r\n";
+        $alerts->runFollowUp();
+        echo "RunAlerts():\r\n";
+        $alerts->runAlerts();
+        echo "RunAcks():\r\n";
+        $alerts->runAcks();
+        echo 'End  : ' . date('r') . "\r\n";
+    }
+    $alerts_lock->release();
 }
-
-$alerts_lock->release();