learnpress / inc / libraries / wp-background-process / classes / wp-background-process.php

wp-background-process.php in LearnPress – WordPress LMS Plugin for Create and Sell Online Courses 4.4.1, at inc/libraries/wp-background-process/classes/wp-background-process.php

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1	<?php
2	/**
3	* WP Background Process
4	*
5	* @package WP-Background-Processing
6	*/
7
8	/**
9	* Abstract WP_Background_Process class.
10	*
11	* @abstract
12	* @extends WP_Async_Request
13	*/
14	abstract class WP_Background_Process extends WP_Async_Request {
15
16	/**
17	* Action
18	*
19	* (default value: 'background_process')
20	*
21	* @var string
22	* @access protected
23	*/
24	protected $action = 'background_process';
25
26	/**
27	* Start time of current process.
28	*
29	* (default value: 0)
30	*
31	* @var int
32	* @access protected
33	*/
34	protected $start_time = 0;
35
36	/**
37	* Cron_hook_identifier
38	*
39	* @var mixed
40	* @access protected
41	*/
42	protected $cron_hook_identifier;
43
44	/**
45	* Cron_interval_identifier
46	*
47	* @var mixed
48	* @access protected
49	*/
50	protected $cron_interval_identifier;
51
52	/**
53	* Initiate new background process
54	*/
55	public function __construct() {
56	parent::__construct();
57
58	$this->cron_hook_identifier = $this->identifier . '_cron';
59	$this->cron_interval_identifier = $this->identifier . '_cron_interval';
60
61	add_action( $this->cron_hook_identifier, array( $this, 'handle_cron_healthcheck' ) );
62	add_filter( 'cron_schedules', array( $this, 'schedule_cron_healthcheck' ) );
63	}
64
65	/**
66	* Dispatch
67	*
68	* @access public
69	* @return array\|WP_Error
70	*/
71	public function dispatch() {
72	// Schedule the cron healthcheck.
73	$this->schedule_event();
74
75	// Perform remote post.
76	return parent::dispatch();
77	}
78
79	/**
80	* Push to queue
81	*
82	* @param mixed $data Data.
83	*
84	* @return $this
85	*/
86	public function push_to_queue( $data ) {
87	$this->data[] = $data;
88
89	return $this;
90	}
91
92	/**
93	* Save queue
94	*
95	* @return $this
96	*/
97	public function save() {
98	$key = $this->generate_key();
99
100	if ( ! empty( $this->data ) ) {
101	update_site_option( $key, $this->data );
102	}
103
104	return $this;
105	}
106
107	/**
108	* Update queue
109	*
110	* @param string $key Key.
111	* @param array $data Data.
112	*
113	* @return $this
114	*/
115	public function update( $key, $data ) {
116	if ( ! empty( $data ) ) {
117	update_site_option( $key, $data );
118	}
119
120	return $this;
121	}
122
123	/**
124	* Delete queue
125	*
126	* @param string $key Key.
127	*
128	* @return $this
129	*/
130	public function delete( $key ) {
131	delete_site_option( $key );
132
133	return $this;
134	}
135
136	/**
137	* Generate key
138	*
139	* Generates a unique key based on microtime. Queue items are
140	* given a unique key so that they can be merged upon save.
141	*
142	* @param int $length Length.
143	*
144	* @return string
145	*/
146	protected function generate_key( $length = 64 ) {
147	$unique = md5( microtime() . rand() );
148	$prepend = $this->identifier . '_batch_';
149
150	return substr( $prepend . $unique, 0, $length );
151	}
152
153	/**
154	* Maybe process queue
155	*
156	* Checks whether data exists within the queue and that
157	* the process is not already running.
158	*/
159	public function maybe_handle() {
160	// Don't lock up other requests while processing
161	session_write_close();
162
163	if ( $this->is_process_running() ) {
164	// Background process already running.
165	wp_die();
166	}
167
168	if ( $this->is_queue_empty() ) {
169	// No data to process.
170	wp_die();
171	}
172
173	check_ajax_referer( $this->identifier, 'nonce' );
174
175	$this->handle();
176
177	wp_die();
178	}
179
180	/**
181	* Is queue empty
182	*
183	* @return bool
184	*/
185	protected function is_queue_empty() {
186	global $wpdb;
187
188	$table = $wpdb->options;
189	$column = 'option_name';
190
191	if ( is_multisite() ) {
192	$table = $wpdb->sitemeta;
193	$column = 'meta_key';
194	}
195
196	$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';
197
198	$count = $wpdb->get_var( $wpdb->prepare( "
199	SELECT COUNT(*)
200	FROM {$table}
201	WHERE {$column} LIKE %s
202	", $key ) );
203
204	return ( $count > 0 ) ? false : true;
205	}
206
207	/**
208	* Is process running
209	*
210	* Check whether the current process is already running
211	* in a background process.
212	*/
213	protected function is_process_running() {
214	if ( get_site_transient( $this->identifier . '_process_lock' ) ) {
215	// Process already running.
216	return true;
217	}
218
219	return false;
220	}
221
222	/**
223	* Lock process
224	*
225	* Lock the process so that multiple instances can't run simultaneously.
226	* Override if applicable, but the duration should be greater than that
227	* defined in the time_exceeded() method.
228	*/
229	protected function lock_process() {
230	$this->start_time = time(); // Set start time of current process.
231
232	$lock_duration = ( property_exists( $this, 'queue_lock_time' ) ) ? $this->queue_lock_time : 60; // 1 minute
233	$lock_duration = apply_filters( $this->identifier . '_queue_lock_time', $lock_duration );
234
235	set_site_transient( $this->identifier . '_process_lock', microtime(), $lock_duration );
236	}
237
238	/**
239	* Unlock process
240	*
241	* Unlock the process so that other instances can spawn.
242	*
243	* @return $this
244	*/
245	protected function unlock_process() {
246	delete_site_transient( $this->identifier . '_process_lock' );
247
248	return $this;
249	}
250
251	/**
252	* Get batch
253	*
254	* @return stdClass Return the first batch from the queue
255	*/
256	protected function get_batch() {
257	global $wpdb;
258
259	$table = $wpdb->options;
260	$column = 'option_name';
261	$key_column = 'option_id';
262	$value_column = 'option_value';
263
264	if ( is_multisite() ) {
265	$table = $wpdb->sitemeta;
266	$column = 'meta_key';
267	$key_column = 'meta_id';
268	$value_column = 'meta_value';
269	}
270
271	$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';
272
273	$query = $wpdb->get_row( $wpdb->prepare( "
274	SELECT *
275	FROM {$table}
276	WHERE {$column} LIKE %s
277	ORDER BY {$key_column} ASC
278	LIMIT 1
279	", $key ) );
280
281	$batch = new stdClass();
282	$batch->key = $query->$column;
283	$batch->data = maybe_unserialize( $query->$value_column );
284
285	return $batch;
286	}
287
288	/**
289	* Handle
290	*
291	* Pass each queue item to the task handler, while remaining
292	* within server memory and time limit constraints.
293	*/
294	protected function handle() {
295	$this->lock_process();
296
297	do {
298	$batch = $this->get_batch();
299
300	foreach ( $batch->data as $key => $value ) {
301	$task = $this->task( $value );
302
303	if ( false !== $task ) {
304	$batch->data[ $key ] = $task;
305	} else {
306	unset( $batch->data[ $key ] );
307	}
308
309	if ( $this->time_exceeded() \|\| $this->memory_exceeded() ) {
310	// Batch limits reached.
311	break;
312	}
313	}
314
315	// Update or delete current batch.
316	if ( ! empty( $batch->data ) ) {
317	$this->update( $batch->key, $batch->data );
318	} else {
319	$this->delete( $batch->key );
320	}
321	} while ( ! $this->time_exceeded() && ! $this->memory_exceeded() && ! $this->is_queue_empty() );
322
323	$this->unlock_process();
324
325	// Start next batch or complete process.
326	if ( ! $this->is_queue_empty() ) {
327	$this->dispatch();
328	} else {
329	$this->complete();
330	}
331
332	wp_die();
333	}
334
335	/**
336	* Memory exceeded
337	*
338	* Ensures the batch process never exceeds 90%
339	* of the maximum WordPress memory.
340	*
341	* @return bool
342	*/
343	protected function memory_exceeded() {
344	$memory_limit = $this->get_memory_limit() * 0.9; // 90% of max memory
345	$current_memory = memory_get_usage( true );
346	$return = false;
347
348	if ( $current_memory >= $memory_limit ) {
349	$return = true;
350	}
351
352	return apply_filters( $this->identifier . '_memory_exceeded', $return );
353	}
354
355	/**
356	* Get memory limit
357	*
358	* @return int
359	*/
360	protected function get_memory_limit() {
361	if ( function_exists( 'ini_get' ) ) {
362	$memory_limit = ini_get( 'memory_limit' );
363	} else {
364	// Sensible default.
365	$memory_limit = '128M';
366	}
367
368	if ( ! $memory_limit \|\| - 1 === intval( $memory_limit ) ) {
369	// Unlimited, set to 32GB.
370	$memory_limit = '32000M';
371	}
372
373	return wp_convert_hr_to_bytes( $memory_limit );
374	}
375
376	/**
377	* Time exceeded.
378	*
379	* Ensures the batch never exceeds a sensible time limit.
380	* A timeout limit of 30s is common on shared hosting.
381	*
382	* @return bool
383	*/
384	protected function time_exceeded() {
385	$finish = $this->start_time + apply_filters( $this->identifier . '_default_time_limit', 20 ); // 20 seconds
386	$return = false;
387
388	if ( time() >= $finish ) {
389	$return = true;
390	}
391
392	return apply_filters( $this->identifier . '_time_exceeded', $return );
393	}
394
395	/**
396	* Complete.
397	*
398	* Override if applicable, but ensure that the below actions are
399	* performed, or, call parent::complete().
400	*/
401	protected function complete() {
402	// Unschedule the cron healthcheck.
403	$this->clear_scheduled_event();
404	}
405
406	/**
407	* Schedule cron healthcheck
408	*
409	* @access public
410	*
411	* @param mixed $schedules Schedules.
412	*
413	* @return mixed
414	*/
415	public function schedule_cron_healthcheck( $schedules ) {
416	$interval = apply_filters( $this->identifier . '_cron_interval', 5 );
417
418	if ( property_exists( $this, 'cron_interval' ) ) {
419	$interval = apply_filters( $this->identifier . '_cron_interval', $this->cron_interval );
420	}
421
422	// Adds every 5 minutes to the existing schedules.
423	$schedules[ $this->identifier . '_cron_interval' ] = array(
424	'interval' => MINUTE_IN_SECONDS * $interval,
425	'display' => sprintf( __( 'Every %d Minutes' ), $interval ),
426	);
427
428	return $schedules;
429	}
430
431	/**
432	* Handle cron healthcheck
433	*
434	* Restart the background process if not already running
435	* and data exists in the queue.
436	*/
437	public function handle_cron_healthcheck() {
438	if ( $this->is_process_running() ) {
439	// Background process already running.
440	exit;
441	}
442
443	if ( $this->is_queue_empty() ) {
444	// No data to process.
445	$this->clear_scheduled_event();
446	exit;
447	}
448
449	$this->handle();
450
451	exit;
452	}
453
454	/**
455	* Schedule event
456	*/
457	protected function schedule_event() {
458	if ( ! wp_next_scheduled( $this->cron_hook_identifier ) ) {
459	wp_schedule_event( time(), $this->cron_interval_identifier, $this->cron_hook_identifier );
460	}
461	}
462
463	/**
464	* Clear scheduled event
465	*/
466	protected function clear_scheduled_event() {
467	$timestamp = wp_next_scheduled( $this->cron_hook_identifier );
468
469	if ( $timestamp ) {
470	wp_unschedule_event( $timestamp, $this->cron_hook_identifier );
471	}
472	}
473
474	/**
475	* Cancel Process
476	*
477	* Stop processing queue items, clear cronjob and delete batch.
478	*
479	*/
480	public function cancel_process() {
481	if ( ! $this->is_queue_empty() ) {
482	$batch = $this->get_batch();
483
484	$this->delete( $batch->key );
485
486	wp_clear_scheduled_hook( $this->cron_hook_identifier );
487	}
488
489	}
490
491	/**
492	* Task
493	*
494	* Override this method to perform any actions required on each
495	* queue item. Return the modified item for further processing
496	* in the next pass through. Or, return false to remove the
497	* item from the queue.
498	*
499	* @param mixed $item Queue item to iterate over.
500	*
501	* @return mixed
502	*/
503	abstract protected function task( $item );
504
505	}
506