Bugfix GetAllKeys() of Memcache

- Abstract Memcache and Memcached implementation

src/Core/Cache/TraitMemcacheCommand.php

@@ -0,0 +1,106 @@
+<?php
+
+namespace Friendica\Core\Cache;
+
+use Friendica\Network\HTTPException\InternalServerErrorException;
+
+/**
+ * Trait for Memcache to add a custom version of the
+ * method getAllKeys() since this isn't working anymore
+ *
+ * Adds the possibility to directly communicate with the memcache too
+ */
+trait TraitMemcacheCommand
+{
+	/**
+	 * @var string server address
+	 */
+	protected $server;
+
+	/**
+	 * @var int server port
+	 */
+	protected $port;
+
+	/**
+	 * Retrieves the stored keys of the memcache instance
+	 * Uses custom commands, which aren't bound to the used instance of the class
+	 *
+	 * @todo Due the fact that we use a custom command, there are race conditions possible:
+	 *       - $this->memcache(d) adds a key
+	 *       - $this->getMemcacheKeys is called directly "after"
+	 *       - But $this->memcache(d) isn't finished adding the key, so getMemcacheKeys doesn't find it
+	 *
+	 * @return array All keys of the memcache instance
+	 *
+	 * @throws InternalServerErrorException
+	 */
+	protected function getMemcacheKeys()
+	{
+		$string = $this->sendMemcacheCommand("stats items");
+		$lines  = explode("\r\n", $string);
+		$slabs  = [];
+		$keys   = [];
+
+		foreach ($lines as $line) {
+
+			if (preg_match("/STAT items:([\d]+):number ([\d]+)/", $line, $matches)) {
+
+				if (isset($matches[1])) {
+					if (!in_array($matches[1], $keys)) {
+						$slabs[] = $matches[1];
+						$string  = $this->sendMemcacheCommand("stats cachedump " . $matches[1] . " " . $matches[2]);
+						preg_match_all("/ITEM (.*?) /", $string, $matches);
+						$keys = array_merge($keys, $matches[1]);
+					}
+				}
+			}
+		}
+
+		return $keys;
+	}
+
+	/**
+	 * Taken directly from memcache PECL source
+	 * Sends a command to the memcache instance and returns the result
+	 * as a string
+	 *
+	 * http://pecl.php.net/package/memcache
+	 *
+	 * @param string $command The command to send to the Memcache server
+	 *
+	 * @return string The returned buffer result
+	 *
+	 * @throws InternalServerErrorException In case the memcache server isn't available (anymore)
+	 */
+	protected function sendMemcacheCommand(string $command)
+	{
+		$s = @fsockopen($this->server, $this->port);
+		if (!$s) {
+			throw new InternalServerErrorException("Cant connect to:" . $this->server . ':' . $this->port);
+		}
+
+		fwrite($s, $command . "\r\n");
+		$buf = '';
+
+		while ((!feof($s))) {
+
+			$buf .= fgets($s, 256);
+
+			if (strpos($buf, "END\r\n") !== false) { // stat says end
+				break;
+			}
+
+			if (strpos($buf, "DELETED\r\n") !== false || strpos($buf, "NOT_FOUND\r\n") !== false) { // delete says these
+				break;
+			}
+
+			if (strpos($buf, "OK\r\n") !== false) { // flush_all says ok
+				break;
+			}
+		}
+
+		fclose($s);
+		return ($buf);
+	}
+}