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          *
  26          * @brief Sets a lock for a given name
  27          *
  28          * @param string $key The Name of the lock
  29          * @param integer $timeout Seconds until we give up
  30          *
  31          * @return boolean Was the lock successful?
  32          */
  33         public function acquireLock($key, $timeout = 120)
  34         {
  35                 $got_lock = false;
  36                 $start = time();
  37
  38                 $cachekey = self::getCacheKey($key);
  39
  40                 do {
  41                         $lock = $this->cache->get($cachekey);
  42                         // When we do want to lock something that was already locked by us.
  43                         if ((int)$lock == getmypid()) {
  44                                 $got_lock = true;
  45                         }
  46
  47                         // When we do want to lock something new
  48                         if (is_null($lock)) {
  49                                 // At first initialize it with "0"
  50                                 $this->cache->add($cachekey, 0);
  51                                 // Now the value has to be "0" because otherwise the key was used by another process meanwhile
  52                                 if ($this->cache->compareSet($cachekey, 0, getmypid(), 300)) {
  53                                         $got_lock = true;
  54                                         $this->markAcquire($key);
  55                                 }
  56                         }
  57
  58                         if (!$got_lock && ($timeout > 0)) {
  59                                 usleep(rand(10000, 200000));
  60                         }
  61                 } while (!$got_lock && ((time() - $start) < $timeout));
  62
  63                 return $got_lock;
  64         }
  65
  66         /**
  67          * @brief Removes a lock if it was set by us
  68          *
  69          * @param string $key Name of the lock
  70          */
  71         public function releaseLock($key)
  72         {
  73                 $cachekey = self::getCacheKey($key);
  74
  75                 $this->cache->compareDelete($cachekey, getmypid());
  76                 $this->markRelease($key);
  77         }
  78
  79         /**
  80          * @brief Checks, if a key is currently locked to a process
  81          *
  82          * @param string $key The name of the lock
  83          * @return bool
  84          */
  85         public function isLocked($key)
  86         {
  87                 $cachekey = self::getCacheKey($key);
  88                 $lock = $this->cache->get($cachekey);
  89                 return isset($lock) && ($lock !== false);
  90         }
  91
  92         /**
  93          * @param string $key   The original key
  94          * @return string               The cache key used for the cache
  95          */
  96         private static function getCacheKey($key) {
  97                 return self::getApp()->get_hostname() . ";lock:" . $key;
  98         }
  99 }