redesign of locking & caching

- New Factory "CacheDriverFactory" for Cache and Locks
- Adding Redis/Memcached Locking
- Moved Lock to Core
- other improvements

src/Core/Lock/SemaphoreLockDriver.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+class SemaphoreLockDriver extends AbstractLockDriver
+{
+	public function __construct()
+	{
+		if (!function_exists('sem_get')) {
+			throw new \Exception('Semaphore lock not supported');
+		}
+	}
+
+	/**
+	 * @brief Creates a semaphore key
+	 *
+	 * @param string $key Name of the lock
+	 *
+	 * @return integer the semaphore key
+	 */
+	private static function semaphoreKey(string $key): int
+	{
+		$temp = get_temppath();
+
+		$file = $temp.'/'.$key.'.sem';
+
+		if (!file_exists($file)) {
+			file_put_contents($file, $key);
+		}
+
+		return ftok($file, 'f');
+	}
+
+	/**
+	 *
+	 * @brief Sets a lock for a given name
+	 *
+	 * @param string $key The Name of the lock
+	 * @param integer $timeout Seconds until we give up
+	 *
+	 * @return boolean Was the lock successful?
+	 */
+	public function acquireLock(string $key, int $timeout = 120)
+	{
+		$this->acquiredLocks[$key] = sem_get(self::semaphoreKey($key));
+		if ($this->acquiredLocks[$key]) {
+			return sem_acquire($this->acquiredLocks[$key], ($timeout == 0));
+		}
+	}
+
+	/**
+	 * @brief Removes a lock if it was set by us
+	 *
+	 * @param string $key Name of the lock
+	 *
+	 * @return mixed
+	 */
+	public function releaseLock(string $key)
+	{
+		if (empty($this->acquiredLocks[$key])) {
+			return false;
+		} else {
+			$success = @sem_release($this->acquiredLocks[$key]);
+			unset($this->acquiredLocks[$key]);
+			return $success;
+		}
+	}
+}