<?php
/**
* Semaphore Lock Management
* Adapted from WP Social under the GPL - thanks to Alex King (https://github.com/crowdfavorite/wp-social)
*/
class UpdraftPlus_Semaphore {
/**
* Initializes the semaphore object.
*
* @static
* @return UpdraftPlus_Semaphore
*/
public static function factory() {
return new self;
}
/**
* Lock Broke
*
* @var boolean
*/
protected $lock_broke = false;
public $lock_name = 'lock';
/**
* Attempts to start the lock. If the rename works, the lock is started.
*
* @return bool
*/
public function lock() {
global $wpdb, $updraftplus;
// Attempt to set the lock
$affected = $wpdb->query("
UPDATE $wpdb->options
SET option_name = 'updraftplus_locked_".$this->lock_name."'
WHERE option_name = 'updraftplus_unlocked_".$this->lock_name."'
");
if ('0' == $affected && !$this->stuck_check()) {
$updraftplus->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
return false;
}
// Check to see if all processes are complete
$affected = $wpdb->query("
UPDATE $wpdb->options
SET option_value = CAST(option_value AS UNSIGNED) + 1
WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
AND option_value = '0'
");
if ('1' != $affected) {
if (!$this->stuck_check()) {
$updraftplus->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
return false;
}
// Reset the semaphore to 1
$wpdb->query("
UPDATE $wpdb->options
SET option_value = '1'
WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
");
$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') reset to 1');
}
// Set the lock time
$wpdb->query($wpdb->prepare("
UPDATE $wpdb->options
SET option_value = %s
WHERE option_name = 'updraftplus_last_lock_time_".$this->lock_name."'
", current_time('mysql', 1)));
$updraftplus->log('Set semaphore last lock ('.$this->lock_name.') time to '.current_time('mysql', 1));
$updraftplus->log('Semaphore lock ('.$this->lock_name.') complete');
return true;
}
public static function ensure_semaphore_exists($semaphore) {
// Make sure the options for semaphores exist
global $wpdb, $updraftplus;
$results = $wpdb->get_results("
SELECT option_id
FROM $wpdb->options
WHERE option_name IN ('updraftplus_locked_$semaphore', 'updraftplus_unlocked_$semaphore', 'updraftplus_last_lock_time_$semaphore', 'updraftplus_semaphore_$semaphore')
");
if (!is_array($results) || count($results) < 3) {
if (is_array($results) && count($results) > 0) {
$updraftplus->log("Semaphore ($semaphore, ".$wpdb->options.") in an impossible/broken state - fixing (".count($results).")");
} else {
$updraftplus->log("Semaphore ($semaphore, ".$wpdb->options.") being initialised");
}
$wpdb->query("
DELETE FROM $wpdb->options
WHERE option_name IN ('updraftplus_locked_$semaphore', 'updraftplus_unlocked_$semaphore', 'updraftplus_last_lock_time_$semaphore', 'updraftplus_semaphore_$semaphore')
");
$wpdb->query($wpdb->prepare("
INSERT INTO $wpdb->options (option_name, option_value, autoload)
VALUES
('updraftplus_unlocked_$semaphore', '1', 'no'),
('updraftplus_last_lock_time_$semaphore', '%s', 'no'),
('updraftplus_semaphore_$semaphore', '0', 'no')
", current_time('mysql', 1)));
}
}
/**
* Increment the semaphore.
*
* @param array $filters
* @return Updraft_Semaphore
*/
public function increment(array $filters = array()) {
global $wpdb, $updraftplus;
if (count($filters)) {
// Loop through all of the filters and increment the semaphore
foreach ($filters as $priority) {
for ($i = 0, $j = count($priority); $i < $j; ++$i) {
$this->increment();
}
}
} else {
$wpdb->query("
UPDATE $wpdb->options
SET option_value = CAST(option_value AS UNSIGNED) + 1
WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
");
$updraftplus->log('Incremented the semaphore ('.$this->lock_name.') by 1');
}
return $this;
}
/**
* Decrements the semaphore.
*
* @return void
*/
public function decrement() {
global $wpdb, $updraftplus;
$wpdb->query("
UPDATE $wpdb->options
SET option_value = CAST(option_value AS UNSIGNED) - 1
WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
AND CAST(option_value AS UNSIGNED) > 0
");
$updraftplus->log('Decremented the semaphore ('.$this->lock_name.') by 1');
}
/**
* Unlocks the process.
*
* @return bool
*/
public function unlock() {
global $wpdb, $updraftplus;
// Decrement for the master process.
$this->decrement();
$result = $wpdb->query("
UPDATE $wpdb->options
SET option_name = 'updraftplus_unlocked_".$this->lock_name."'
WHERE option_name = 'updraftplus_locked_".$this->lock_name."'
");
if ('1' == $result) {
$updraftplus->log('Semaphore ('.$this->lock_name.') unlocked');
return true;
}
$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') still locked ('.$result.')');
return false;
}
/**
* Attempts to jiggle the stuck lock loose.
*
* @return bool
*/
private function stuck_check() {
global $wpdb, $updraftplus;
// Check to see if we already broke the lock.
if ($this->lock_broke) {
return true;
}
$current_time = current_time('mysql', 1);
$three_minutes_before = gmdate('Y-m-d H:i:s', time()-(defined('UPDRAFTPLUS_SEMAPHORE_LOCK_WAIT') ? UPDRAFTPLUS_SEMAPHORE_LOCK_WAIT : 180));
$affected = $wpdb->query($wpdb->prepare("
UPDATE $wpdb->options
SET option_value = %s
WHERE option_name = 'updraftplus_last_lock_time_".$this->lock_name."'
AND option_value <= %s
", $current_time, $three_minutes_before));
if ('1' == $affected) {
$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') was stuck, set lock time to '.$current_time);
$this->lock_broke = true;
return true;
}
// Check if lock is greater that 24 hours
$last_lock_time = strtotime(UpdraftPlus_Options::get_updraft_option('updraftplus_last_lock_time_'.$this->lock_name, $current_time));
$next_day = strtotime($current_time.' +1 day');
if ($last_lock_time > $next_day) {
$this->lock_broke = true;
return true;
}
return false;
}
/**
* Remove a given lock from the options table in the database
*
* @return Boolean True if the lock has successfully been removed, false otherwise
*/
public function delete_lock() {
global $wpdb;
return (bool) $wpdb->query($wpdb->prepare("DELETE FROM {$wpdb->options} WHERE option_name = %s", $this->lock_name));
}
} // End UpdraftPlus_Semaphore