2017-06-04 09:26:21 +02:00
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<?php
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namespace Friendica\Util;
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/**
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* @file src/Util/Lock.php
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* @brief Functions for preventing parallel execution of functions
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*
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*/
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2017-06-04 17:59:20 +02:00
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use Friendica\Core\Config;
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use Memcache;
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2017-06-04 09:26:21 +02:00
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use dba;
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use dbm;
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/**
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* @brief This class contain Functions for preventing parallel execution of functions
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*/
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class Lock {
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2017-06-04 17:59:20 +02:00
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/**
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* @brief Check for memcache and open a connection if configured
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*
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* @return object|boolean The memcache object - or "false" if not successful
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*/
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public static function memcache() {
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if (!function_exists('memcache_connect')) {
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return false;
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}
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if (!Config::get('system', 'memcache')) {
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return false;
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}
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$memcache_host = Config::get('system', 'memcache_host', '127.0.0.1');
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$memcache_port = Config::get('system', 'memcache_port', 11211);
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$memcache = new Memcache;
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if (!$memcache->connect($memcache_host, $memcache_port)) {
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return false;
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}
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return $memcache;
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}
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2017-06-04 09:26:21 +02:00
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2017-06-04 10:36:08 +02:00
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/**
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* @brief Sets a lock for a given name
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*
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* @param string $fn_name Name of the lock
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* @param integer $timeout Seconds until we give up
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*
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* @return boolean Was the lock successful?
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*/
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2017-06-04 20:59:50 +02:00
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public static function set($fn_name, $timeout = 120) {
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2017-06-04 09:26:21 +02:00
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$got_lock = false;
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$start = time();
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2017-06-04 17:59:20 +02:00
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$memcache = self::memcache();
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if (is_object($memcache)) {
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2017-06-05 16:59:53 +02:00
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$wait_sec = 0.2;
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2017-06-04 17:59:20 +02:00
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$cachekey = get_app()->get_hostname().";lock:".$fn_name;
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do {
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$lock = $memcache->get($cachekey);
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if (!is_bool($lock)) {
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$pid = (int)$lock;
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// When the process id isn't used anymore, we can safely claim the lock for us.
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// Or we do want to lock something that was already locked by us.
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if (!posix_kill($pid, 0) OR ($pid == getmypid())) {
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$lock = false;
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}
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}
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if (is_bool($lock)) {
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$memcache->set($cachekey, getmypid(), MEMCACHE_COMPRESSED, 300);
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$got_lock = true;
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}
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if (!$got_lock) {
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2017-06-05 16:59:53 +02:00
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usleep($wait_sec * 1000000);
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2017-06-04 17:59:20 +02:00
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}
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2017-06-05 16:59:53 +02:00
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} while (!$got_lock AND ((time(true) - $start) < $timeout));
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2017-06-04 17:59:20 +02:00
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return $got_lock;
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}
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2017-06-04 20:59:50 +02:00
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$wait_sec = 2;
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2017-06-04 09:26:21 +02:00
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do {
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2017-06-04 14:59:29 +02:00
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dba::lock('locks');
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2017-06-04 10:36:08 +02:00
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$lock = dba::select('locks', array('locked', 'pid'), array('name' => $fn_name), array('limit' => 1));
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if (dbm::is_result($lock)) {
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if ($lock['locked']) {
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// When the process id isn't used anymore, we can safely claim the lock for us.
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if (!posix_kill($lock['pid'], 0)) {
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$lock['locked'] = false;
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}
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// We want to lock something that was already locked by us? So we got the lock.
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if ($lock['pid'] == getmypid()) {
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$got_lock = true;
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}
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}
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if (!$lock['locked']) {
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dba::update('locks', array('locked' => true, 'pid' => getmypid()), array('name' => $fn_name));
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$got_lock = true;
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}
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2017-06-04 09:26:21 +02:00
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} elseif (!dbm::is_result($lock)) {
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2017-06-04 10:36:08 +02:00
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dba::insert('locks', array('name' => $fn_name, 'locked' => true, 'pid' => getmypid()));
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2017-06-04 09:26:21 +02:00
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$got_lock = true;
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}
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2017-06-04 14:59:29 +02:00
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dba::unlock();
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2017-06-04 09:26:21 +02:00
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if (!$got_lock) {
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sleep($wait_sec);
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}
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} while (!$got_lock AND ((time() - $start) < $timeout));
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return $got_lock;
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}
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2017-06-04 10:36:08 +02:00
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/**
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* @brief Removes a lock if it was set by us
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*
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* @param string $fn_name Name of the lock
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*/
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2017-06-04 09:26:21 +02:00
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public static function remove($fn_name) {
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2017-06-04 17:59:20 +02:00
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$memcache = self::memcache();
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if (is_object($memcache)) {
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$cachekey = get_app()->get_hostname().";lock:".$fn_name;
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$lock = $memcache->get($cachekey);
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if (!is_bool($lock)) {
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if ((int)$lock == getmypid()) {
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$memcache->delete($cachekey);
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}
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}
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return;
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}
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2017-06-04 10:36:08 +02:00
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dba::update('locks', array('locked' => false, 'pid' => 0), array('name' => $fn_name, 'pid' => getmypid()));
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2017-06-04 09:26:21 +02:00
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return;
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}
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2017-06-04 17:59:20 +02:00
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/**
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* @brief Removes all lock that were set by us
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*/
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public static function removeAll() {
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$memcache = self::memcache();
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if (is_object($memcache)) {
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// We cannot delete all cache entries, but this doesn't matter with memcache
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return;
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}
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dba::update('locks', array('locked' => false, 'pid' => 0), array('pid' => getmypid()));
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return;
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}
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2017-06-04 09:26:21 +02:00
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}
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