src/Core/Lock/DatabaseLock.php

   1 <?php
   2
   3 namespace Friendica\Core\Lock;
   4
   5 use Friendica\Core\BaseLock;
   6 use Friendica\Core\Cache\Duration;
   7 use Friendica\Database\Database;
   8 use Friendica\Util\DateTimeFormat;
   9
  10 /**
  11  * Locking driver that stores the locks in the database
  12  */
  13 class DatabaseLock extends BaseLock
  14 {
  15         /**
  16          * The current ID of the process
  17          *
  18          * @var int
  19          */
  20         private $pid;
  21
  22         /**
  23          * @var Database The database connection of Friendica
  24          */
  25         private $dba;
  26
  27         /**
  28          * @param null|int $pid The Id of the current process (null means determine automatically)
  29          */
  30         public function __construct(Database $dba, $pid = null)
  31         {
  32                 $this->dba = $dba;
  33                 $this->pid = isset($pid) ? $pid : getmypid();
  34         }
  35
  36         /**
  37          * (@inheritdoc)
  38          */
  39         public function acquire($key, $timeout = 120, $ttl = Duration::FIVE_MINUTES)
  40         {
  41                 $got_lock = false;
  42                 $start    = time();
  43
  44                 do {
  45                         $this->dba->lock('locks');
  46                         $lock = $this->dba->selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  47
  48                         if ($this->dba->isResult($lock)) {
  49                                 if ($lock['locked']) {
  50                                         // We want to lock something that was already locked by us? So we got the lock.
  51                                         if ($lock['pid'] == $this->pid) {
  52                                                 $got_lock = true;
  53                                         }
  54                                 }
  55                                 if (!$lock['locked']) {
  56                                         $this->dba->update('locks', ['locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')], ['name' => $key]);
  57                                         $got_lock = true;
  58                                 }
  59                         } else {
  60                                 $this->dba->insert('locks', ['name' => $key, 'locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')]);
  61                                 $got_lock = true;
  62                                 $this->markAcquire($key);
  63                         }
  64
  65                         $this->dba->unlock();
  66
  67                         if (!$got_lock && ($timeout > 0)) {
  68                                 usleep(rand(100000, 2000000));
  69                         }
  70                 } while (!$got_lock && ((time() - $start) < $timeout));
  71
  72                 return $got_lock;
  73         }
  74
  75         /**
  76          * (@inheritdoc)
  77          */
  78         public function release($key, $override = false)
  79         {
  80                 if ($override) {
  81                         $where = ['name' => $key];
  82                 } else {
  83                         $where = ['name' => $key, 'pid' => $this->pid];
  84                 }
  85
  86                 if ($this->dba->exists('locks', $where)) {
  87                         $return = $this->dba->delete('locks', $where);
  88                 } else {
  89                         $return = false;
  90                 }
  91
  92                 $this->markRelease($key);
  93
  94                 return $return;
  95         }
  96
  97         /**
  98          * (@inheritdoc)
  99          */
 100         public function releaseAll($override = false)
 101         {
 102                 $success = parent::releaseAll($override);
 103
 104                 if ($override) {
 105                         $where = ['1 = 1'];
 106                 } else {
 107                         $where = ['pid' => $this->pid];
 108                 }
 109                 $return = $this->dba->delete('locks', $where);
 110
 111                 $this->acquiredLocks = [];
 112
 113                 return $return && $success;
 114         }
 115
 116         /**
 117          * (@inheritdoc)
 118          */
 119         public function isLocked($key)
 120         {
 121                 $lock = $this->dba->selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
 122
 123                 if ($this->dba->isResult($lock)) {
 124                         return $lock['locked'] !== false;
 125                 } else {
 126                         return false;
 127                 }
 128         }
 129
 130         /**
 131          * {@inheritDoc}
 132          */
 133         public function getName()
 134         {
 135                 return Type::DATABASE;
 136         }
 137
 138         /**
 139          * {@inheritDoc}
 140          */
 141         public function getLocks(string $prefix = '')
 142         {
 143                 if (empty($prefix)) {
 144                         $where = ['`expires` >= ?', DateTimeFormat::utcNow()];
 145                 } else {
 146                         $where = ['`expires` >= ? AND `name` LIKE CONCAT(?, \'%\')', DateTimeFormat::utcNow(), $prefix];
 147                 }
 148
 149                 $stmt = $this->dba->select('locks', ['name'], $where);
 150
 151                 $keys = [];
 152                 while ($key = $this->dba->fetch($stmt)) {
 153                         array_push($keys, $key['name']);
 154                 }
 155                 $this->dba->close($stmt);
 156
 157                 return $keys;
 158         }
 159 }