updraftplus / includes / class-semaphore.php

class-semaphore.php in UpdraftPlus: WP Backup & Migration Plugin 1.16.5, at includes/class-semaphore.php

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1	<?php
2	/**
3	* Semaphore Lock Management
4	* Adapted from WP Social under the GPL - thanks to Alex King (https://github.com/crowdfavorite/wp-social)
5	*/
6	class UpdraftPlus_Semaphore {
7
8	/**
9	* Initializes the semaphore object.
10	*
11	* @static
12	* @return UpdraftPlus_Semaphore
13	*/
14	public static function factory() {
15	return new self;
16	}
17
18	/**
19	* Lock Broke
20	*
21	* @var boolean
22	*/
23	protected $lock_broke = false;
24
25	public $lock_name = 'lock';
26
27	/**
28	* Attempts to start the lock. If the rename works, the lock is started.
29	*
30	* @return bool
31	*/
32	public function lock() {
33	global $wpdb, $updraftplus;
34
35	// Attempt to set the lock
36	$affected = $wpdb->query("
37	UPDATE $wpdb->options
38	SET option_name = 'updraftplus_locked_".$this->lock_name."'
39	WHERE option_name = 'updraftplus_unlocked_".$this->lock_name."'
40	");
41
42	if ('0' == $affected && !$this->stuck_check()) {
43	$updraftplus->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
44	return false;
45	}
46
47	// Check to see if all processes are complete
48	$affected = $wpdb->query("
49	UPDATE $wpdb->options
50	SET option_value = CAST(option_value AS UNSIGNED) + 1
51	WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
52	AND option_value = '0'
53	");
54	if ('1' != $affected) {
55	if (!$this->stuck_check()) {
56	$updraftplus->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
57	return false;
58	}
59
60	// Reset the semaphore to 1
61	$wpdb->query("
62	UPDATE $wpdb->options
63	SET option_value = '1'
64	WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
65	");
66
67	$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') reset to 1');
68	}
69
70	// Set the lock time
71	$wpdb->query($wpdb->prepare("
72	UPDATE $wpdb->options
73	SET option_value = %s
74	WHERE option_name = 'updraftplus_last_lock_time_".$this->lock_name."'
75	", current_time('mysql', 1)));
76	$updraftplus->log('Set semaphore last lock ('.$this->lock_name.') time to '.current_time('mysql', 1));
77
78	$updraftplus->log('Semaphore lock ('.$this->lock_name.') complete');
79	return true;
80	}
81
82	public static function ensure_semaphore_exists($semaphore) {
83	// Make sure the options for semaphores exist
84	global $wpdb, $updraftplus;
85	$results = $wpdb->get_results("
86	SELECT option_id
87	FROM $wpdb->options
88	WHERE option_name IN ('updraftplus_locked_$semaphore', 'updraftplus_unlocked_$semaphore', 'updraftplus_last_lock_time_$semaphore', 'updraftplus_semaphore_$semaphore')
89	");
90
91	if (!is_array($results) \|\| count($results) < 3) {
92
93	if (is_array($results) && count($results) > 0) {
94	$updraftplus->log("Semaphore ($semaphore, ".$wpdb->options.") in an impossible/broken state - fixing (".count($results).")");
95	} else {
96	$updraftplus->log("Semaphore ($semaphore, ".$wpdb->options.") being initialised");
97	}
98
99	$wpdb->query("
100	DELETE FROM $wpdb->options
101	WHERE option_name IN ('updraftplus_locked_$semaphore', 'updraftplus_unlocked_$semaphore', 'updraftplus_last_lock_time_$semaphore', 'updraftplus_semaphore_$semaphore')
102	");
103
104	$wpdb->query($wpdb->prepare("
105	INSERT INTO $wpdb->options (option_name, option_value, autoload)
106	VALUES
107	('updraftplus_unlocked_$semaphore', '1', 'no'),
108	('updraftplus_last_lock_time_$semaphore', '%s', 'no'),
109	('updraftplus_semaphore_$semaphore', '0', 'no')
110	", current_time('mysql', 1)));
111	}
112	}
113
114	/**
115	* Increment the semaphore.
116	*
117	* @param array $filters
118	* @return Updraft_Semaphore
119	*/
120	public function increment(array $filters = array()) {
121	global $wpdb;
122
123	if (count($filters)) {
124	// Loop through all of the filters and increment the semaphore
125	foreach ($filters as $priority) {
126	for ($i = 0, $j = count($priority); $i < $j; ++$i) {
127	$this->increment();
128	}
129	}
130	} else {
131	$wpdb->query("
132	UPDATE $wpdb->options
133	SET option_value = CAST(option_value AS UNSIGNED) + 1
134	WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
135	");
136	$updraftplus->log('Incremented the semaphore ('.$this->lock_name.') by 1');
137	}
138
139	return $this;
140	}
141
142	/**
143	* Decrements the semaphore.
144	*
145	* @return void
146	*/
147	public function decrement() {
148	global $wpdb, $updraftplus;
149
150	$wpdb->query("
151	UPDATE $wpdb->options
152	SET option_value = CAST(option_value AS UNSIGNED) - 1
153	WHERE option_name = 'updraftplus_semaphore_".$this->lock_name."'
154	AND CAST(option_value AS UNSIGNED) > 0
155	");
156	$updraftplus->log('Decremented the semaphore ('.$this->lock_name.') by 1');
157	}
158
159	/**
160	* Unlocks the process.
161	*
162	* @return bool
163	*/
164	public function unlock() {
165	global $wpdb, $updraftplus;
166
167	// Decrement for the master process.
168	$this->decrement();
169
170	$result = $wpdb->query("
171	UPDATE $wpdb->options
172	SET option_name = 'updraftplus_unlocked_".$this->lock_name."'
173	WHERE option_name = 'updraftplus_locked_".$this->lock_name."'
174	");
175
176	if ('1' == $result) {
177	$updraftplus->log('Semaphore ('.$this->lock_name.') unlocked');
178	return true;
179	}
180
181	$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') still locked ('.$result.')');
182	return false;
183	}
184
185	/**
186	* Attempts to jiggle the stuck lock loose.
187	*
188	* @return bool
189	*/
190	private function stuck_check() {
191	global $wpdb, $updraftplus;
192
193	// Check to see if we already broke the lock.
194	if ($this->lock_broke) {
195	return true;
196	}
197
198	$current_time = current_time('mysql', 1);
199	$three_minutes_before = gmdate('Y-m-d H:i:s', time()-(defined('UPDRAFTPLUS_SEMAPHORE_LOCK_WAIT') ? UPDRAFTPLUS_SEMAPHORE_LOCK_WAIT : 180));
200
201	$affected = $wpdb->query($wpdb->prepare("
202	UPDATE $wpdb->options
203	SET option_value = %s
204	WHERE option_name = 'updraftplus_last_lock_time_".$this->lock_name."'
205	AND option_value <= %s
206	", $current_time, $three_minutes_before));
207
208	if ('1' == $affected) {
209	$updraftplus->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') was stuck, set lock time to '.$current_time);
210	$this->lock_broke = true;
211	return true;
212	}
213
214	return false;
215	}
216	} // End UpdraftPlus_Semaphore
217