iwp-client / backup / class.semaphore.php

class.semaphore.php in InfiniteWP Client trunk, at backup/class.semaphore.php

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1	<?php
2	// Adapted from WP Social under the GPL - thanks to Alex King (https://github.com/crowdfavorite/wp-social)
3	/**
4	* Semaphore Lock Management
5	*/
6
7	if ( ! defined('ABSPATH') )
8	die();
9
10	class IWP_MMB_Semaphore {
11
12	/**
13	* Initializes the semaphore object.
14	*
15	* @static
16	*/
17	public static function factory() {
18	return new self;
19	}
20
21	/**
22	* @var bool
23	*/
24	protected $lock_broke = false;
25
26	public $lock_name = 'lock';
27
28	/**
29	* Attempts to start the lock. If the rename works, the lock is started.
30	*
31	* @return bool
32	*/
33	public function lock() {
34	global $wpdb, $iwp_backup_core,$iwp_mmb_core;
35
36	// Attempt to set the lock
37	$affected = $wpdb->query("
38	UPDATE $wpdb->options
39	SET option_name = 'IWP_locked_".$this->lock_name."'
40	WHERE option_name = 'IWP_unlocked_".$this->lock_name."'
41	");
42
43	if ($affected == '0' and !$this->stuck_check()) {
44	$iwp_backup_core->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
45	return false;
46	}
47
48	// Check to see if all processes are complete
49	$affected = $wpdb->query("
50	UPDATE $wpdb->options
51	SET option_value = CAST(option_value AS UNSIGNED) + 1
52	WHERE option_name = 'IWP_semaphore_".$this->lock_name."'
53	AND option_value = '0'
54	");
55	if ($affected != '1') {
56	if (!$this->stuck_check()) {
57	$iwp_backup_core->log('Semaphore lock ('.$this->lock_name.', '.$wpdb->options.') failed (line '.__LINE__.')');
58	return false;
59	}
60
61	// Reset the semaphore to 1
62	$wpdb->query("
63	UPDATE $wpdb->options
64	SET option_value = '1'
65	WHERE option_name = 'IWP_semaphore_".$this->lock_name."'
66	");
67
68	$iwp_backup_core->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') reset to 1');
69	}
70
71	// Set the lock time
72	$wpdb->query($wpdb->prepare("
73	UPDATE $wpdb->options
74	SET option_value = %s
75	WHERE option_name = 'IWP_last_lock_time_".$this->lock_name."'
76	", current_time('mysql', 1)));
77	$iwp_backup_core->log('Set semaphore last lock ('.$this->lock_name.') time to '.current_time('mysql', 1));
78
79	$iwp_backup_core->log('Semaphore lock ('.$this->lock_name.') complete');
80	$iwp_mmb_core->iwp_update_option($option_name = 'IWP_backup_status',$option_value = '1');
81	$iwp_mmb_core->iwp_delete_option('IWP_running_backupID');
82	return true;
83	}
84
85	/**
86	* Increment the semaphore.
87	*
88	* @param array $filters
89	* @return Social_Semaphore
90	*/
91	public function increment(array $filters = array()) {
92	global $wpdb, $iwp_backup_core;
93
94	if (count($filters)) {
95	// Loop through all of the filters and increment the semaphore
96	foreach ($filters as $priority) {
97	for ($i = 0, $j = count($priority); $i < $j; ++$i) {
98	$this->increment();
99	}
100	}
101	}
102	else {
103	$wpdb->query("
104	UPDATE $wpdb->options
105	SET option_value = CAST(option_value AS UNSIGNED) + 1
106	WHERE option_name = 'IWP_semaphore_".$this->lock_name."'
107	");
108	$iwp_backup_core->log('Incremented the semaphore ('.$this->lock_name.') by 1');
109	}
110
111	return $this;
112	}
113
114	/**
115	* Decrements the semaphore.
116	*
117	* @return void
118	*/
119	public function decrement() {
120	global $wpdb, $iwp_backup_core;
121
122	$wpdb->query("
123	UPDATE $wpdb->options
124	SET option_value = CAST(option_value AS UNSIGNED) - 1
125	WHERE option_name = 'IWP_semaphore_".$this->lock_name."'
126	AND CAST(option_value AS UNSIGNED) > 0
127	");
128	$iwp_backup_core->log('Decremented the semaphore ('.$this->lock_name.') by 1');
129	}
130
131	/**
132	* Unlocks the process.
133	*
134	* @return bool
135	*/
136	public function unlock() {
137	global $wpdb, $iwp_backup_core, $iwp_mmb_core;
138
139	// Decrement for the master process.
140	$this->decrement();
141
142	$result = $wpdb->query("
143	UPDATE $wpdb->options
144	SET option_name = 'IWP_unlocked_".$this->lock_name."'
145	WHERE option_name = 'IWP_locked_".$this->lock_name."'
146	");
147	$iwp_mmb_core->iwp_update_option($option_name = 'IWP_backup_status',$option_value = '0');
148	if ($result == '1') {
149	$iwp_backup_core->log('Semaphore ('.$this->lock_name.') unlocked');
150	return true;
151	}
152
153	$iwp_backup_core->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') still locked ('.$result.')');
154	return false;
155	}
156
157	/**
158	* Attempts to jiggle the stuck lock loose.
159	*
160	* @return bool
161	*/
162	private function stuck_check() {
163	global $wpdb, $iwp_backup_core;
164
165	// Check to see if we already broke the lock.
166	if ($this->lock_broke) {
167	return true;
168	}
169
170	$current_time = current_time('mysql', 1);
171	$three_minutes_before = gmdate('Y-m-d H:i:s', time()-(defined('IWP_SEMAPHORE_LOCK_WAIT') ? IWP_SEMAPHORE_LOCK_WAIT : 180));
172
173	$affected = $wpdb->query($wpdb->prepare("
174	UPDATE $wpdb->options
175	SET option_value = %s
176	WHERE option_name = 'IWP_last_lock_time_".$this->lock_name."'
177	AND option_value <= %s
178	", $current_time, $three_minutes_before));
179
180	if ('1' == $affected) {
181	$iwp_backup_core->log('Semaphore ('.$this->lock_name.', '.$wpdb->options.') was stuck, set lock time to '.$current_time);
182	$this->lock_broke = true;
183	return true;
184	}
185
186	return false;
187	}
188
189	}
190