fix: Use memcached to lock daily processes on Distributed Pollers (#7735)

* fix: use memcached to lock daily processes on Distributed Pollers * All the locks!
2024-10-07 16:52:45 +00:00 · 2017-11-24 03:37:52 -06:00
parent 9c0a74debb
commit 2e73b75297
13 changed files with 603 additions and 230 deletions
--- a/LibreNMS/Util/MemcacheLock.php
+++ b/LibreNMS/Util/MemcacheLock.php
@@ -0,0 +1,146 @@
+<?php
+/**
+ * MemcacheLock.php
+ *
+ * -Description-
+ *
+ * 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/>.
+ *
+ * @package    LibreNMS
+ * @link       http://librenms.org
+ * @copyright  2017 Tony Murray
+ * @author     Tony Murray <murraytony@gmail.com>
+ */
+
+namespace LibreNMS\Util;
+
+use LibreNMS\Config;
+use LibreNMS\Exceptions\LockException;
+use LibreNMS\Interfaces\Lock;
+
+class MemcacheLock implements Lock
+{
+    private $namespace = 'lock';
+    private $lock_name;
+    private $poller_name;
+    private $memcached;
+    private $host;
+    private $port;
+
+    private function __construct($lock_name)
+    {
+        if (!class_exists('Memcached')) {
+            throw new LockException("Missing PHP Memcached extension, this is required for distributed polling.");
+        }
+
+        // check all config vars or fallback
+        $this->host = Config::get('distributed_poller_memcached_host', Config::get('memcached.host', 'localhost'));
+        $this->port = Config::get('distributed_poller_memcached_port', Config::get('memcached.port', 11211));
+
+        $this->lock_name = "$this->namespace.$lock_name";
+        $this->poller_name = Config::get('distributed_poller_name');
+        $this->memcached = new \Memcached();
+        $this->memcached->addServer($this->host, $this->port);
+    }
+
+    /**
+     * Given a lock name, try to acquire the lock, exiting on failure.
+     * On success return a Lock object.
+     * @param string $lock_name Name of lock
+     * @param int $timeout Try for this many seconds to see if we can acquire the lock.  Default is no wait. A negative timeout will wait forever.
+     * @return Lock
+     */
+    public static function lockOrDie($lock_name, $timeout = 0)
+    {
+        try {
+            return self::lock($lock_name, $timeout);
+        } catch (LockException $e) {
+            echo $e->getMessage() . PHP_EOL;
+            exit(1);
+        }
+    }
+
+    /**
+     * Given a lock name, try to acquire the lock.
+     * On success return a Lock object, or on failure return false.
+     * @param string $lock_name Name of lock
+     * @param int $wait Try for this many seconds to see if we can acquire the lock.  Default is no wait. A negative timeout will wait forever.
+     * @param int $expiration number of seconds to hold lock for, default is forever
+     * @return Lock
+     * @throws LockException
+     */
+    public static function lock($lock_name, $wait = 0, $expiration = null)
+    {
+        $lock = new self($lock_name);
+
+        if (!$lock->isConnected()) {
+            throw new LockException("Could not connect to memcached ($lock->host:$lock->port)");
+        }
+
+        $owner = true;
+        for ($i = 0; $i <= $wait || $wait < 0; $i++) {
+            $owner = $lock->memcached->get($lock->lock_name);
+            if ($owner == false) {
+                break;  // try to acquire the lock
+            }
+            sleep(1);
+        }
+
+        if ($owner) {
+            if ($owner == $lock->poller_name) {
+                throw new LockException("This poller ($owner) already owns the lock: $lock->lock_name");
+            }
+            throw new LockException("Lock $lock->lock_name already acquired by $owner");
+        }
+
+        $lock->memcached->set($lock->lock_name, $lock->poller_name, $expiration);
+        $owner = $lock->memcached->get($lock->lock_name);
+        if ($owner != $lock->poller_name) {
+            throw new LockException("Another poller ($owner) has lock: $lock->lock_name");
+        }
+
+        return $lock;
+    }
+
+    private function isConnected()
+    {
+        return $this->memcached->getVersion() != false;
+    }
+
+    public function __destruct()
+    {
+        $this->release();
+    }
+
+    /**
+     * Release the lock.
+     */
+    public function release()
+    {
+        $this->memcached->delete($this->lock_name);
+    }
+
+    /**
+     * Renew an expiring lock
+     *
+     * @param int $expiration number of seconds to hold lock for (null to cancel expiration)
+     */
+    public function renew($expiration)
+    {
+        $owner = $this->memcached->get($this->lock_name);
+        if ($owner == $this->poller_name) {
+            $this->memcached->set($this->lock_name, $this->poller_name, $expiration);
+        }
+    }
+}