src/Core/Lock/CacheLockDriver.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 use Friendica\Core\Cache;
   6 use Friendica\Core\Cache\IMemoryCacheDriver;
   7
   8 class CacheLockDriver extends AbstractLockDriver
   9 {
  10         /**
  11          * @var \Friendica\Core\Cache\ICacheDriver;
  12          */
  13         private $cache;
  14
  15         /**
  16          * CacheLockDriver constructor.
  17          *
  18          * @param IMemoryCacheDriver $cache The CacheDriver for this type of lock
  19          */
  20         public function __construct(IMemoryCacheDriver $cache)
  21         {
  22                 $this->cache = $cache;
  23         }
  24
  25         /**
  26          * (@inheritdoc)
  27          */
  28         public function acquireLock($key, $timeout = 120, $ttl = Cache::FIVE_MINUTES)
  29         {
  30                 $got_lock = false;
  31                 $start = time();
  32
  33                 $cachekey = self::getLockKey($key);
  34
  35                 do {
  36                         $lock = $this->cache->get($cachekey);
  37                         // When we do want to lock something that was already locked by us.
  38                         if ((int)$lock == getmypid()) {
  39                                 $got_lock = true;
  40                         }
  41
  42                         // When we do want to lock something new
  43                         if (is_null($lock)) {
  44                                 // At first initialize it with "0"
  45                                 $this->cache->add($cachekey, 0);
  46                                 // Now the value has to be "0" because otherwise the key was used by another process meanwhile
  47                                 if ($this->cache->compareSet($cachekey, 0, getmypid(), $ttl)) {
  48                                         $got_lock = true;
  49                                         $this->markAcquire($key);
  50                                 }
  51                         }
  52
  53                         if (!$got_lock && ($timeout > 0)) {
  54                                 usleep(rand(10000, 200000));
  55                         }
  56                 } while (!$got_lock && ((time() - $start) < $timeout));
  57
  58                 return $got_lock;
  59         }
  60
  61         /**
  62          * (@inheritdoc)
  63          */
  64         public function releaseLock($key)
  65         {
  66                 $cachekey = self::getLockKey($key);
  67
  68                 $this->cache->compareDelete($cachekey, getmypid());
  69                 $this->markRelease($key);
  70         }
  71
  72         /**
  73          * (@inheritdoc)
  74          */
  75         public function isLocked($key)
  76         {
  77                 $cachekey = self::getLockKey($key);
  78                 $lock = $this->cache->get($cachekey);
  79                 return isset($lock) && ($lock !== false);
  80         }
  81
  82         /**
  83          * @param string $key   The original key
  84          * @return string               The cache key used for the cache
  85          */
  86         private static function getLockKey($key) {
  87                 return "lock:" . $key;
  88         }
  89 }