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| author | Andreas Fischer <bantu@phpbb.com> | 2012-12-04 20:26:43 +0100 |
|---|---|---|
| committer | Andreas Fischer <bantu@phpbb.com> | 2012-12-04 20:26:43 +0100 |
| commit | 2fdd039e5223b7acea3795811326945bd649bf49 (patch) | |
| tree | b0efba74b1bdc2eaad2443d7e65f61c66ee66a1e /phpBB/includes/lock | |
| parent | d7a23df2d9c3a9f93d8477e164edef0d263d8dcb (diff) | |
| parent | 3e093c282a63df4d16b212859fd8137fd2bbca81 (diff) | |
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Merge remote-tracking branch 'p/ticket/10103' into develop
* p/ticket/10103:
[ticket/10103] New and improved wording.
[ticket/10103] Assert with messages.
[ticket/10103] assertLessThan/assertGreaterThan.
[ticket/10103] Inline assignment is bad?
[ticket/10103] $rv had too few characters.
[ticket/10103] Correct flock class documentation.
[ticket/10103] Try a longer sleep for travis.
[ticket/10103] Convert the rest of the tree to flock class.
[ticket/10103] Test for flock lock class, with concurrency no less.
[ticket/10103] Use flock lock class in messenger.
[ticket/10103] Factor out flock lock class.
Diffstat (limited to 'phpBB/includes/lock')
| -rw-r--r-- | phpBB/includes/lock/flock.php | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/phpBB/includes/lock/flock.php b/phpBB/includes/lock/flock.php new file mode 100644 index 0000000000..5c2288ce1b --- /dev/null +++ b/phpBB/includes/lock/flock.php @@ -0,0 +1,133 @@ +<?php +/** +* +* @package phpBB3 +* @copyright (c) 2012 phpBB Group +* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2 +* +*/ + +/** +* @ignore +*/ +if (!defined('IN_PHPBB')) +{ + exit; +} + +/** +* File locking class +* @package phpBB3 +*/ +class phpbb_lock_flock +{ + /** + * Path to the file to which access is controlled + * + * @var string + */ + private $path; + + /** + * File pointer for the lock file + * @var string + */ + private $lock_fp; + + /** + * Constructor. + * + * You have to call acquire() to actually acquire the lock. + * + * @param string $path Path to the file to which access is controlled + */ + public function __construct($path) + { + $this->path = $path; + $this->lock_fp = null; + } + + /** + * Tries to acquire the lock. + * + * If the lock is already held by another process, this call will block + * until the other process releases the lock. If a lock is acquired and + * is not released before script finishes but the process continues to + * live (apache/fastcgi) then subsequent processes trying to acquire + * the same lock will be blocked forever. + * + * If the lock is already held by the same process via another instance + * of this class, this call will block forever. + * + * If flock function is disabled in php or fails to work, lock + * acquisition will fail and false will be returned. + * + * @return bool true if lock was acquired + * false otherwise + */ + public function acquire() + { + if ($this->locked) + { + return false; + } + + // For systems that can't have two processes opening + // one file for writing simultaneously + if (file_exists($this->path . '.lock')) + { + $mode = 'rb'; + } + else + { + $mode = 'wb'; + } + + $this->lock_fp = @fopen($this->path . '.lock', $mode); + + if ($mode == 'wb') + { + if (!$this->lock_fp) + { + // Two processes may attempt to create lock file at the same time. + // Have the losing process try opening the lock file again for reading + // on the assumption that the winning process created it + $mode = 'rb'; + $this->lock_fp = @fopen($this->path . '.lock', $mode); + } + else + { + // Only need to set mode when the lock file is written + @chmod($this->path . '.lock', 0666); + } + } + + if ($this->lock_fp) + { + @flock($this->lock_fp, LOCK_EX); + } + + return (bool) $this->lock_fp; + } + + /** + * Releases the lock. + * + * The lock must have been previously obtained, that is, acquire() call + * was issued and returned true. + * + * Note: Attempting to release a lock that is already released, + * that is, calling release() multiple times, is harmless. + * + * @return null + */ + public function release() + { + if ($this->lock_fp) + { + @flock($this->lock_fp, LOCK_UN); + fclose($this->lock_fp); + $this->lock_fp = null; + } + } +} |