src/Core/Lock/DatabaseLock.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   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;
  23
  24 use Friendica\Core\BaseLock;
  25 use Friendica\Core\Cache\Duration;
  26 use Friendica\Database\Database;
  27 use Friendica\Util\DateTimeFormat;
  28
  29 /**
  30  * Locking driver that stores the locks in the database
  31  */
  32 class DatabaseLock extends BaseLock
  33 {
  34         /**
  35          * The current ID of the process
  36          *
  37          * @var int
  38          */
  39         private $pid;
  40
  41         /**
  42          * @var Database The database connection of Friendica
  43          */
  44         private $dba;
  45
  46         /**
  47          * @param null|int $pid The Id of the current process (null means determine automatically)
  48          */
  49         public function __construct(Database $dba, $pid = null)
  50         {
  51                 $this->dba = $dba;
  52                 $this->pid = isset($pid) ? $pid : getmypid();
  53         }
  54
  55         /**
  56          * (@inheritdoc)
  57          */
  58         public function acquire($key, $timeout = 120, $ttl = Duration::FIVE_MINUTES)
  59         {
  60                 $got_lock = false;
  61                 $start    = time();
  62
  63                 do {
  64                         $this->dba->lock('locks');
  65                         $lock = $this->dba->selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
  66
  67                         if ($this->dba->isResult($lock)) {
  68                                 if ($lock['locked']) {
  69                                         // We want to lock something that was already locked by us? So we got the lock.
  70                                         if ($lock['pid'] == $this->pid) {
  71                                                 $got_lock = true;
  72                                         }
  73                                 }
  74                                 if (!$lock['locked']) {
  75                                         $this->dba->update('locks', ['locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')], ['name' => $key]);
  76                                         $got_lock = true;
  77                                 }
  78                         } else {
  79                                 $this->dba->insert('locks', ['name' => $key, 'locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')]);
  80                                 $got_lock = true;
  81                                 $this->markAcquire($key);
  82                         }
  83
  84                         $this->dba->unlock();
  85
  86                         if (!$got_lock && ($timeout > 0)) {
  87                                 usleep(rand(100000, 2000000));
  88                         }
  89                 } while (!$got_lock && ((time() - $start) < $timeout));
  90
  91                 return $got_lock;
  92         }
  93
  94         /**
  95          * (@inheritdoc)
  96          */
  97         public function release($key, $override = false)
  98         {
  99                 if ($override) {
 100                         $where = ['name' => $key];
 101                 } else {
 102                         $where = ['name' => $key, 'pid' => $this->pid];
 103                 }
 104
 105                 if ($this->dba->exists('locks', $where)) {
 106                         $return = $this->dba->delete('locks', $where);
 107                 } else {
 108                         $return = false;
 109                 }
 110
 111                 $this->markRelease($key);
 112
 113                 return $return;
 114         }
 115
 116         /**
 117          * (@inheritdoc)
 118          */
 119         public function releaseAll($override = false)
 120         {
 121                 $success = parent::releaseAll($override);
 122
 123                 if ($override) {
 124                         $where = ['1 = 1'];
 125                 } else {
 126                         $where = ['pid' => $this->pid];
 127                 }
 128                 $return = $this->dba->delete('locks', $where);
 129
 130                 $this->acquiredLocks = [];
 131
 132                 return $return && $success;
 133         }
 134
 135         /**
 136          * (@inheritdoc)
 137          */
 138         public function isLocked($key)
 139         {
 140                 $lock = $this->dba->selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
 141
 142                 if ($this->dba->isResult($lock)) {
 143                         return $lock['locked'] !== false;
 144                 } else {
 145                         return false;
 146                 }
 147         }
 148
 149         /**
 150          * {@inheritDoc}
 151          */
 152         public function getName()
 153         {
 154                 return Type::DATABASE;
 155         }
 156
 157         /**
 158          * {@inheritDoc}
 159          */
 160         public function getLocks(string $prefix = '')
 161         {
 162                 if (empty($prefix)) {
 163                         $where = ['`expires` >= ?', DateTimeFormat::utcNow()];
 164                 } else {
 165                         $where = ['`expires` >= ? AND `name` LIKE CONCAT(?, \'%\')', DateTimeFormat::utcNow(), $prefix];
 166                 }
 167
 168                 $stmt = $this->dba->select('locks', ['name'], $where);
 169
 170                 $keys = [];
 171                 while ($key = $this->dba->fetch($stmt)) {
 172                         array_push($keys, $key['name']);
 173                 }
 174                 $this->dba->close($stmt);
 175
 176                 return $keys;
 177         }
 178 }