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\Database\DBM;
   8 use Friendica\Util\DateTimeFormat;
   9
  10 /**
  11  * Locking driver that stores the locks in the database
  12  */
  13 class DatabaseLockDriver extends AbstractLockDriver
  14 {
  15         /**
  16          * (@inheritdoc)
  17          */
  18         public function acquireLock($key, $timeout = 120, $ttl = Cache::FIVE_MINUTES)
  19         {
  20                 $got_lock = false;
  21                 $start = time();
  22
  23                 do {
  24                         dba::lock('locks');
  25                         $lock = dba::selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  26
  27                         if (DBM::is_result($lock)) {
  28                                 if ($lock['locked']) {
  29                                         // We want to lock something that was already locked by us? So we got the lock.
  30                                         if ($lock['pid'] == getmypid()) {
  31                                                 $got_lock = true;
  32                                         }
  33                                 }
  34                                 if (!$lock['locked']) {
  35                                         dba::update('locks', ['locked' => true, 'pid' => getmypid(), 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')], ['name' => $key]);
  36                                         $got_lock = true;
  37                                 }
  38                         } else {
  39                                 dba::insert('locks', ['name' => $key, 'locked' => true, 'pid' => getmypid(), 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')]);
  40                                 $got_lock = true;
  41                                 $this->markAcquire($key);
  42                         }
  43
  44                         dba::unlock();
  45
  46                         if (!$got_lock && ($timeout > 0)) {
  47                                 usleep(rand(100000, 2000000));
  48                         }
  49                 } while (!$got_lock && ((time() - $start) < $timeout));
  50
  51                 return $got_lock;
  52         }
  53
  54         /**
  55          * (@inheritdoc)
  56          */
  57         public function releaseLock($key)
  58         {
  59                 dba::delete('locks', ['name' => $key, 'pid' => getmypid()]);
  60
  61                 $this->markRelease($key);
  62
  63                 return;
  64         }
  65
  66         /**
  67          * (@inheritdoc)
  68          */
  69         public function releaseAll()
  70         {
  71                 dba::delete('locks', ['pid' => getmypid()]);
  72
  73                 $this->acquiredLocks = [];
  74         }
  75
  76         /**
  77          * (@inheritdoc)
  78          */
  79         public function isLocked($key)
  80         {
  81                 $lock = dba::selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  82
  83                 if (DBM::is_result($lock)) {
  84                         return $lock['locked'] !== false;
  85                 } else {
  86                         return false;
  87                 }
  88         }
  89 }