src/Core/Lock/Type/CacheLock.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2021, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Core\Lock\Type;
  23
  24 use Friendica\Core\Cache\Enum\Duration;
  25 use Friendica\Core\Cache\IMemoryCache;
  26
  27 class CacheLock extends BaseLock
  28 {
  29         /**
  30          * @var string The static prefix of all locks inside the cache
  31          */
  32         const CACHE_PREFIX = 'lock:';
  33
  34         /**
  35          * @var \Friendica\Core\Cache\ICache;
  36          */
  37         private $cache;
  38
  39         /**
  40          * CacheLock constructor.
  41          *
  42          * @param IMemoryCache $cache The CacheDriver for this type of lock
  43          */
  44         public function __construct(IMemoryCache $cache)
  45         {
  46                 $this->cache = $cache;
  47         }
  48
  49         /**
  50          * (@inheritdoc)
  51          */
  52         public function acquire($key, $timeout = 120, $ttl = Duration::FIVE_MINUTES)
  53         {
  54                 $got_lock = false;
  55                 $start    = time();
  56
  57                 $cachekey = self::getLockKey($key);
  58
  59                 do {
  60                         $lock = $this->cache->get($cachekey);
  61                         // When we do want to lock something that was already locked by us.
  62                         if ((int)$lock == getmypid()) {
  63                                 $got_lock = true;
  64                         }
  65
  66                         // When we do want to lock something new
  67                         if (is_null($lock)) {
  68                                 // At first initialize it with "0"
  69                                 $this->cache->add($cachekey, 0);
  70                                 // Now the value has to be "0" because otherwise the key was used by another process meanwhile
  71                                 if ($this->cache->compareSet($cachekey, 0, getmypid(), $ttl)) {
  72                                         $got_lock = true;
  73                                         $this->markAcquire($key);
  74                                 }
  75                         }
  76
  77                         if (!$got_lock && ($timeout > 0)) {
  78                                 usleep(rand(10000, 200000));
  79                         }
  80                 } while (!$got_lock && ((time() - $start) < $timeout));
  81
  82                 return $got_lock;
  83         }
  84
  85         /**
  86          * (@inheritdoc)
  87          */
  88         public function release($key, $override = false)
  89         {
  90                 $cachekey = self::getLockKey($key);
  91
  92                 if ($override) {
  93                         $return = $this->cache->delete($cachekey);
  94                 } else {
  95                         $return = $this->cache->compareDelete($cachekey, getmypid());
  96                 }
  97                 $this->markRelease($key);
  98
  99                 return $return;
 100         }
 101
 102         /**
 103          * (@inheritdoc)
 104          */
 105         public function isLocked($key)
 106         {
 107                 $cachekey = self::getLockKey($key);
 108                 $lock     = $this->cache->get($cachekey);
 109                 return isset($lock) && ($lock !== false);
 110         }
 111
 112         /**
 113          * {@inheritDoc}
 114          */
 115         public function getName()
 116         {
 117                 return $this->cache->getName();
 118         }
 119
 120         /**
 121          * {@inheritDoc}
 122          */
 123         public function getLocks(string $prefix = '')
 124         {
 125                 $locks = $this->cache->getAllKeys(self::CACHE_PREFIX . $prefix);
 126
 127                 array_walk($locks, function (&$lock, $key) {
 128                         $lock = substr($lock, strlen(self::CACHE_PREFIX));
 129                 });
 130
 131                 return $locks;
 132         }
 133
 134         /**
 135          * {@inheritDoc}
 136          */
 137         public function releaseAll($override = false)
 138         {
 139                 $success = parent::releaseAll($override);
 140
 141                 $locks = $this->getLocks();
 142
 143                 foreach ($locks as $lock) {
 144                         if (!$this->release($lock, $override)) {
 145                                 $success = false;
 146                         }
 147                 }
 148
 149                 return $success;
 150         }
 151
 152         /**
 153          * @param string $key The original key
 154          *
 155          * @return string        The cache key used for the cache
 156          */
 157         private static function getLockKey($key)
 158         {
 159                 return self::CACHE_PREFIX . $key;
 160         }
 161 }