redesign of locking & caching

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

src/Core/Lock/CacheLockDriver.php

@@ -0,0 +1,89 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+use Friendica\Core\Cache\ICacheDriver;
+
+class CacheLockDriver extends AbstractLockDriver
+{
+	/**
+	 * @var \Friendica\Core\Cache\ICacheDriver;
+	 */
+	private $cache;
+
+	/**
+	 * CacheLockDriver constructor.
+	 *
+	 * @param ICacheDriver $cache The CacheDriver for this type of lock
+	 */
+	public function __construct(ICacheDriver $cache)
+	{
+		$this->cache = $cache;
+	}
+
+	/**
+	 *
+	 * @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)
+	{
+		$got_lock = false;
+		$start = time();
+
+		$cachekey = get_app()->get_hostname() . ";lock:" . $key;
+
+		do {
+			$lock = $this->cache->get($cachekey);
+
+			if (!is_bool($lock)) {
+				$pid = (int)$lock;
+
+				// When the process id isn't used anymore, we can safely claim the lock for us.
+				// Or we do want to lock something that was already locked by us.
+				if (!posix_kill($pid, 0) || ($pid == getmypid())) {
+					$lock = false;
+				}
+			}
+			if (is_bool($lock)) {
+				$this->cache->set($cachekey, getmypid(), 300);
+				$got_lock = true;
+			}
+
+			if (!$got_lock && ($timeout > 0)) {
+				usleep(rand(10000, 200000));
+			}
+		} while (!$got_lock && ((time() - $start) < $timeout));
+
+		$this->markAcquire($key);
+
+		return $got_lock;
+	}
+
+	/**
+	 * @brief Removes a lock if it was set by us
+	 *
+	 * @param string $key Name of the lock
+	 *
+	 * @return mixed
+	 */
+	public function releaseLock(string $key)
+	{
+		$cachekey = get_app()->get_hostname() . ";lock:" . $key;
+		$lock = $this->cache->get($cachekey);
+
+		if (!is_bool($lock)) {
+			if ((int)$lock == getmypid()) {
+				$this->cache->delete($cachekey);
+			}
+		}
+
+		$this->markRelease($key);
+
+		return;
+	}
+}