src/Core/Lock/DatabaseLockDriver.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 use Friendica\Core\Cache;
   6 use Friendica\Database\DBA;
   7 use Friendica\Util\DateTimeFormat;
   8
   9 /**
  10  * Locking driver that stores the locks in the database
  11  */
  12 class DatabaseLockDriver extends AbstractLockDriver
  13 {
  14         /**
  15          * The current ID of the process
  16          *
  17          * @var int
  18          */
  19         private $pid;
  20
  21         /**
  22          * @param null|int $pid The Id of the current process (null means determine automatically)
  23          */
  24         public function __construct($pid = null)
  25         {
  26                 $this->pid = isset($pid) ? $pid : getmypid();
  27         }
  28
  29         /**
  30          * (@inheritdoc)
  31          */
  32         public function acquireLock($key, $timeout = 120, $ttl = Cache::FIVE_MINUTES)
  33         {
  34                 $got_lock = false;
  35                 $start = time();
  36
  37                 do {
  38                         DBA::lock('locks');
  39                         $lock = DBA::selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  40
  41                         if (DBA::isResult($lock)) {
  42                                 if ($lock['locked']) {
  43                                         // We want to lock something that was already locked by us? So we got the lock.
  44                                         if ($lock['pid'] == $this->pid) {
  45                                                 $got_lock = true;
  46                                         }
  47                                 }
  48                                 if (!$lock['locked']) {
  49                                         DBA::update('locks', ['locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')], ['name' => $key]);
  50                                         $got_lock = true;
  51                                 }
  52                         } else {
  53                                 DBA::insert('locks', ['name' => $key, 'locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')]);
  54                                 $got_lock = true;
  55                                 $this->markAcquire($key);
  56                         }
  57
  58                         DBA::unlock();
  59
  60                         if (!$got_lock && ($timeout > 0)) {
  61                                 usleep(rand(100000, 2000000));
  62                         }
  63                 } while (!$got_lock && ((time() - $start) < $timeout));
  64
  65                 return $got_lock;
  66         }
  67
  68         /**
  69          * (@inheritdoc)
  70          */
  71         public function releaseLock($key)
  72         {
  73                 DBA::delete('locks', ['name' => $key, 'pid' => $this->pid]);
  74
  75                 $this->markRelease($key);
  76
  77                 return;
  78         }
  79
  80         /**
  81          * (@inheritdoc)
  82          */
  83         public function releaseAll()
  84         {
  85                 DBA::delete('locks', ['pid' => $this->pid]);
  86
  87                 $this->acquiredLocks = [];
  88         }
  89
  90         /**
  91          * (@inheritdoc)
  92          */
  93         public function isLocked($key)
  94         {
  95                 $lock = DBA::selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  96
  97                 if (DBA::isResult($lock)) {
  98                         return $lock['locked'] !== false;
  99                 } else {
 100                         return false;
 101                 }
 102         }
 103 }