From f08c28c77a585e35cc17a2248ba61428275ccdd7 Mon Sep 17 00:00:00 2001 From: Oleg Pudeyev Date: Tue, 4 Dec 2012 01:59:27 -0500 Subject: [ticket/10103] Factor out flock lock class. PHPBB3-10103 --- phpBB/includes/lock/flock.php | 124 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 phpBB/includes/lock/flock.php (limited to 'phpBB/includes/lock') diff --git a/phpBB/includes/lock/flock.php b/phpBB/includes/lock/flock.php new file mode 100644 index 0000000000..e24a5f3e1c --- /dev/null +++ b/phpBB/includes/lock/flock.php @@ -0,0 +1,124 @@ +path = $path; + $this->lock_fp = null; + } + + /** + * Tries to acquire the lock. + * + * As a lock may only be held by one process at a time, lock + * acquisition may fail if another process is holding the lock. + * + * @return bool true if lock was acquired + * false otherwise + */ + public function acquire() + { + if ($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; + } + } +} -- cgit v1.2.1 From 4cc81f1ffa62cdbcbb656300c7dd9fbd44cc21fc Mon Sep 17 00:00:00 2001 From: Oleg Pudeyev Date: Tue, 4 Dec 2012 13:44:22 -0500 Subject: [ticket/10103] Correct flock class documentation. PHPBB3-10103 --- phpBB/includes/lock/flock.php | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'phpBB/includes/lock') diff --git a/phpBB/includes/lock/flock.php b/phpBB/includes/lock/flock.php index e24a5f3e1c..09450644bc 100644 --- a/phpBB/includes/lock/flock.php +++ b/phpBB/includes/lock/flock.php @@ -35,9 +35,9 @@ class phpbb_lock_flock private $lock_fp; /** - * Creates an instance of the lock. + * Constructor. * - * You have to call acquire() to actually create the lock. + * You have to call acquire() to actually acquire the lock. * * @param string $path Path to the file access to which is controlled */ @@ -50,8 +50,17 @@ class phpbb_lock_flock /** * Tries to acquire the lock. * - * As a lock may only be held by one process at a time, lock - * acquisition may fail if another process is holding 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 -- cgit v1.2.1 From 3e093c282a63df4d16b212859fd8137fd2bbca81 Mon Sep 17 00:00:00 2001 From: Oleg Pudeyev Date: Tue, 4 Dec 2012 14:05:49 -0500 Subject: [ticket/10103] New and improved wording. PHPBB3-10103 --- phpBB/includes/lock/flock.php | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'phpBB/includes/lock') diff --git a/phpBB/includes/lock/flock.php b/phpBB/includes/lock/flock.php index 09450644bc..5c2288ce1b 100644 --- a/phpBB/includes/lock/flock.php +++ b/phpBB/includes/lock/flock.php @@ -22,7 +22,7 @@ if (!defined('IN_PHPBB')) class phpbb_lock_flock { /** - * Path to the file access to which is controlled + * Path to the file to which access is controlled * * @var string */ @@ -39,7 +39,7 @@ class phpbb_lock_flock * * You have to call acquire() to actually acquire the lock. * - * @param string $path Path to the file access to which is controlled + * @param string $path Path to the file to which access is controlled */ public function __construct($path) { -- cgit v1.2.1