src/Core/Lock/DatabaseLock.php

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