src/Core/Lock/CacheLockDriver.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 use Friendica\Core\Cache\IMemoryCacheDriver;
   6
   7 class CacheLockDriver extends AbstractLockDriver
   8 {
   9         /**
  10          * @var \Friendica\Core\Cache\ICacheDriver;
  11          */
  12         private $cache;
  13
  14         /**
  15          * CacheLockDriver constructor.
  16          *
  17          * @param IMemoryCacheDriver $cache The CacheDriver for this type of lock
  18          */
  19         public function __construct(IMemoryCacheDriver $cache)
  20         {
  21                 $this->cache = $cache;
  22         }
  23
  24         /**
  25          * (@inheritdoc)
  26          */
  27         public function acquireLock($key, $timeout = 120)
  28         {
  29                 $got_lock = false;
  30                 $start = time();
  31
  32                 $cachekey = self::getCacheKey($key);
  33
  34                 do {
  35                         $lock = $this->cache->get($cachekey);
  36                         // When we do want to lock something that was already locked by us.
  37                         if ((int)$lock == getmypid()) {
  38                                 $got_lock = true;
  39                         }
  40
  41                         // When we do want to lock something new
  42                         if (is_null($lock)) {
  43                                 // At first initialize it with "0"
  44                                 $this->cache->add($cachekey, 0);
  45                                 // Now the value has to be "0" because otherwise the key was used by another process meanwhile
  46                                 if ($this->cache->compareSet($cachekey, 0, getmypid(), 300)) {
  47                                         $got_lock = true;
  48                                         $this->markAcquire($key);
  49                                 }
  50                         }
  51
  52                         if (!$got_lock && ($timeout > 0)) {
  53                                 usleep(rand(10000, 200000));
  54                         }
  55                 } while (!$got_lock && ((time() - $start) < $timeout));
  56
  57                 return $got_lock;
  58         }
  59
  60         /**
  61          * (@inheritdoc)
  62          */
  63         public function releaseLock($key)
  64         {
  65                 $cachekey = self::getCacheKey($key);
  66
  67                 $this->cache->compareDelete($cachekey, getmypid());
  68                 $this->markRelease($key);
  69         }
  70
  71         /**
  72          * (@inheritdoc)
  73          */
  74         public function isLocked($key)
  75         {
  76                 $cachekey = self::getCacheKey($key);
  77                 $lock = $this->cache->get($cachekey);
  78                 return isset($lock) && ($lock !== false);
  79         }
  80
  81         /**
  82          * @param string $key   The original key
  83          * @return string               The cache key used for the cache
  84          */
  85         private static function getCacheKey($key) {
  86                 return self::getApp()->get_hostname() . ";lock:" . $key;
  87         }
  88 }