updraftcentral / classes / class-updraft-semaphore.php

class-updraft-semaphore.php in UpdraftCentral Dashboard trunk, at classes/class-updraft-semaphore.php

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1	<?php
2	/**
3	* Semaphore Lock Management
4	*/
5	class Updraft_Semaphore_1_0 {
6
7	/**
8	* Initializes the semaphore object.
9	*
10	* @static
11	* @return Updraft_Semaphore
12	*/
13	public static function factory() {
14	return new self;
15	}
16
17	/**
18	* Lock Broke
19	*
20	* @var boolean
21	*/
22	protected $lock_broke = false;
23
24	/**
25	* Array of loggers
26	*
27	* @var array
28	*/
29	protected $loggers;
30
31	public $lock_name = 'lock';
32
33	/**
34	* Ensures that the semaphore options exists before actually using them
35	*/
36	public function ensure_semaphore_exists() {
37	// Make sure the options for semaphores exist
38	global $wpdb;
39
40	$results = $wpdb->get_results("
41	SELECT option_id
42	FROM $wpdb->options
43	WHERE option_name IN ('updraft_locked_".$this->lock_name."', 'updraft_unlocked_".$this->lock_name."', 'updraft_last_lock_time_".$this->lock_name."', 'updraft_semaphore_".$this->lock_name."')
44	");
45
46	if (!is_array($results) \|\| count($results) < 3) {
47
48	if (is_array($results) && count($results) > 0) {
49	$this->log(sprintf('Semaphore (%s, $s) in an impossible/broken state - fixing (%d)', $this->lock_name, $wpdb->options, count($results)));
50	} else {
51	$this->log(sprintf('Semaphore (%s, %s) being initialised', $this->lock_name, $wpdb->options));
52	}
53
54	$wpdb->query("
55	DELETE FROM $wpdb->options
56	WHERE option_name IN ('updraft_locked_".$this->lock_name."', 'updraft_unlocked_".$this->lock_name."', 'updraft_last_lock_time_".$this->lock_name."', 'updraft_semaphore_".$this->lock_name."')
57	");
58
59	$wpdb->query($wpdb->prepare("
60	INSERT INTO $wpdb->options (option_name, option_value, autoload)
61	VALUES
62	('updraft_unlocked_".$this->lock_name."', '1', 'no'),
63	('updraft_last_lock_time_".$this->lock_name."', '%s', 'no'),
64	('updraft_semaphore_".$this->lock_name."', '0', 'no')
65	", current_time('mysql', 1)));
66	}
67	}
68
69	/**
70	* Attempts to start the lock. If the rename works, the lock is started.
71	*
72	* @return bool
73	*/
74	public function lock() {
75	global $wpdb;
76
77	// Attempt to set the lock
78	$affected = $wpdb->query("
79	UPDATE $wpdb->options
80	SET option_name = 'updraft_locked_".$this->lock_name."'
81	WHERE option_name = 'updraft_unlocked_".$this->lock_name."'
82	");
83
84	if ('0' == $affected && !$this->stuck_check()) {
85	$this->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
86	return false;
87	}
88
89	// Check to see if all processes are complete
90	$affected = $wpdb->query("
91	UPDATE $wpdb->options
92	SET option_value = CAST(option_value AS UNSIGNED) + 1
93	WHERE option_name = 'updraft_semaphore_".$this->lock_name."'
94	AND option_value = '0'
95	");
96	if ('1' != $affected) {
97	if (!$this->stuck_check()) {
98	$this->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
99	return false;
100	}
101
102	// Reset the semaphore to 1
103	$wpdb->query("
104	UPDATE $wpdb->options
105	SET option_value = '1'
106	WHERE option_name = 'updraft_semaphore_".$this->lock_name."'
107	");
108
109	$this->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') reset to 1');
110	}
111
112	// Set the lock time
113	$wpdb->query($wpdb->prepare("
114	UPDATE $wpdb->options
115	SET option_value = %s
116	WHERE option_name = 'updraft_last_lock_time_".$this->lock_name."'
117	", current_time('mysql', 1)));
118	$this->log('Set semaphore last lock ('.$this->lock_name.') time to '.current_time('mysql', 1));
119
120	$this->log('Semaphore lock ('.$this->lock_name.') complete');
121	return true;
122	}
123
124	/**
125	* Increment the semaphore.
126	*
127	* @param array $filters
128	* @return Updraft_Semaphore
129	*/
130	public function increment(array $filters = array()) {
131	global $wpdb;
132
133	if (count($filters)) {
134	// Loop through all of the filters and increment the semaphore
135	foreach ($filters as $priority) {
136	for ($i = 0, $j = count($priority); $i < $j; ++$i) {
137	$this->increment();
138	}
139	}
140	} else {
141	$wpdb->query("
142	UPDATE $wpdb->options
143	SET option_value = CAST(option_value AS UNSIGNED) + 1
144	WHERE option_name = 'updraft_semaphore_".$this->lock_name."'
145	");
146	$this->log('Incremented the semaphore ('.$this->lock_name.') by 1');
147	}
148
149	return $this;
150	}
151
152	/**
153	* Decrements the semaphore.
154	*
155	* @return void
156	*/
157	public function decrement() {
158	global $wpdb;
159
160	$wpdb->query("
161	UPDATE $wpdb->options
162	SET option_value = CAST(option_value AS UNSIGNED) - 1
163	WHERE option_name = 'updraft_semaphore_".$this->lock_name."'
164	AND CAST(option_value AS UNSIGNED) > 0
165	");
166	$this->log('Decremented the semaphore ('.$this->lock_name.') by 1');
167	}
168
169	/**
170	* Unlocks the process.
171	*
172	* @return bool
173	*/
174	public function unlock() {
175	global $wpdb;
176
177	// Decrement for the master process.
178	$this->decrement();
179
180	$result = $wpdb->query("
181	UPDATE $wpdb->options
182	SET option_name = 'updraft_unlocked_".$this->lock_name."'
183	WHERE option_name = 'updraft_locked_".$this->lock_name."'
184	");
185
186	if ('1' == $result) {
187	$this->log('Semaphore ('.$this->lock_name.') unlocked');
188	return true;
189	}
190
191	$this->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') still locked ('.$result.')');
192	return false;
193	}
194
195	/**
196	* Attempts to jiggle the stuck lock loose.
197	*
198	* @return bool
199	*/
200	private function stuck_check() {
201	global $wpdb;
202
203	// Check to see if we already broke the lock.
204	if ($this->lock_broke) {
205	return true;
206	}
207
208	$current_time = current_time('mysql', 1);
209	$three_minutes_before = gmdate('Y-m-d H:i:s', time()-(defined('UPDRAFT_SEMAPHORE_LOCK_WAIT') ? UPDRAFT_SEMAPHORE_LOCK_WAIT : 180));
210
211	$affected = $wpdb->query($wpdb->prepare("
212	UPDATE $wpdb->options
213	SET option_value = %s
214	WHERE option_name = 'updraft_last_lock_time_".$this->lock_name."'
215	AND option_value <= %s
216	", $current_time, $three_minutes_before));
217
218	if ('1' == $affected) {
219	$this->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') was stuck, set lock time to '.$current_time);
220	$this->lock_broke = true;
221	return true;
222	}
223
224	return false;
225	}
226
227	/**
228	* Sets the logger for this instance.
229	*
230	* @param array $loggers - the loggers for this task
231	*/
232	public function set_loggers($loggers) {
233	foreach ($loggers as $logger) {
234	$this->add_logger($logger);
235	}
236	}
237
238	/**
239	* Add a logger to loggers list
240	*
241	* @param Object $logger - a logger for the instance
242	*/
243	public function add_logger($logger) {
244	$this->_loggers[] = $logger;
245	}
246
247	/**
248	* Return list of loggers
249	*
250	* @return array
251	*/
252	public function get_loggers() {
253	return $this->_loggers;
254	}
255
256	/**
257	* Captures and logs any interesting messages
258	*
259	* @param String $message - the error message
260	* @param String $error_type - the error type
261	*
262	* @return void
263	*/
264	public function log($message, $error_type = 'info') {
265	if (defined('UPDRAFTCENTRAL_DISABLE_SEMAPHORE_LOG') && UPDRAFTCENTRAL_DISABLE_SEMAPHORE_LOG) return;
266
267	if (isset($this->_loggers)) {
268	foreach ($this->_loggers as $logger) {
269	$logger->log($error_type, $message);
270	}
271	} else {
272	error_log($message);
273	}
274	}
275	} // End Updraft_Semaphore
276