src/Core/Lock/SemaphoreLockDriver.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 class SemaphoreLockDriver extends AbstractLockDriver
   6 {
   7         private static $semaphore = [];
   8
   9         public function __construct()
  10         {
  11                 if (!function_exists('sem_get')) {
  12                         throw new \Exception('Semaphore lock not supported');
  13                 }
  14         }
  15
  16         /**
  17          * @brief Creates a semaphore key
  18          *
  19          * @param string $key Name of the lock
  20          *
  21          * @return integer the semaphore key
  22          */
  23         private static function semaphoreKey($key)
  24         {
  25                 $temp = get_temppath();
  26
  27                 $file = $temp.'/'.$key.'.sem';
  28
  29                 if (!file_exists($file)) {
  30                         file_put_contents($file, $key);
  31                 }
  32
  33                 return ftok($file, 'f');
  34         }
  35
  36         /**
  37          *
  38          * @brief Sets a lock for a given name
  39          *
  40          * @param string $key The Name of the lock
  41          * @param integer $timeout Seconds until we give up
  42          *
  43          * @return boolean Was the lock successful?
  44          */
  45         public function acquireLock($key, $timeout = 120)
  46         {
  47                 self::$semaphore[$key] = sem_get(self::semaphoreKey($key));
  48                 if (self::$semaphore[$key]) {
  49                         if (sem_acquire(self::$semaphore[$key], ($timeout == 0))) {
  50                                 $this->markAcquire($key);
  51                                 return true;
  52                         }
  53                 }
  54
  55                 return false;
  56         }
  57
  58         /**
  59          * @brief Removes a lock if it was set by us
  60          *
  61          * @param string $key Name of the lock
  62          *
  63          * @return mixed
  64          */
  65         public function releaseLock($key)
  66         {
  67                 if (empty(self::$semaphore[$key])) {
  68                         return false;
  69                 } else {
  70                         $success = @sem_release(self::$semaphore[$key]);
  71                         unset(self::$semaphore[$key]);
  72                         $this->markRelease($key);
  73                         return $success;
  74                 }
  75         }
  76
  77         /**
  78          * @brief Checks, if a key is currently locked to a process
  79          *
  80          * @param string $key The name of the lock
  81          * @return bool
  82          */
  83         public function isLocked($key)
  84         {
  85                 return @sem_get(self::$semaphore[$key]) !== false;
  86         }
  87 }