src/Core/Lock/SemaphoreLockDriver.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 class SemaphoreLockDriver implements ILockDriver
   6 {
   7         /**
   8          * @var array stored semaphores
   9          */
  10         private static $semaphore = [];
  11
  12         /**
  13          * @brief Creates a semaphore key
  14          *
  15          * @param string $key Name of the lock
  16          *
  17          * @return integer the semaphore key
  18          */
  19         private static function semaphoreKey($key)
  20         {
  21                 $temp = get_temppath();
  22
  23                 $file = $temp.'/'.$key.'.sem';
  24
  25                 if (!file_exists($file)) {
  26                         file_put_contents($file, $key);
  27                 }
  28
  29                 return ftok($file, 'f');
  30         }
  31
  32         /**
  33          *
  34          * @brief Sets a lock for a given name
  35          *
  36          * @param string $key The Name of the lock
  37          * @param integer $timeout Seconds until we give up
  38          *
  39          * @return boolean Was the lock successful?
  40          */
  41         public function acquireLock($key, $timeout = 120)
  42         {
  43                 // The second parameter for "sem_acquire" doesn't exist before 5.6.1
  44                 if (function_exists('sem_get') && version_compare(PHP_VERSION, '5.6.1', '>=')) {
  45                         self::$semaphore[$key] = sem_get(self::semaphoreKey($key));
  46                         if (self::$semaphore[$key]) {
  47                                 return sem_acquire(self::$semaphore[$key], ($timeout == 0));
  48                         }
  49                 }
  50         }
  51
  52         /**
  53          * @brief Removes a lock if it was set by us
  54          *
  55          * @param string $key Name of the lock
  56          *
  57          * @return mixed
  58          */
  59         public function releaseLock($key)
  60         {
  61                 if (function_exists('sem_get') && version_compare(PHP_VERSION, '5.6.1', '>=')) {
  62                         if (empty(self::$semaphore[$key])) {
  63                                 return false;
  64                         } else {
  65                                 $success = @sem_release(self::$semaphore[$key]);
  66                                 unset(self::$semaphore[$key]);
  67                                 return $success;
  68                         }
  69                 }
  70         }
  71
  72         /**
  73          * @brief Removes all lock that were set by us
  74          *
  75          * @return void
  76          */
  77         public function releaseAll()
  78         {
  79                 // not needed/supported
  80                 return;
  81         }
  82 }