groups / lib / core / class-groups-lock.php

class-groups-lock.php in Groups – Memberships and Access Control 4.7.0, at lib/core/class-groups-lock.php

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1	<?php
2	/**
3	* class-groups-lock.php
4	*
5	* Copyright (c) "kento" Karim Rahimpur www.itthinx.com
6	*
7	* This code is released under the GNU General Public License.
8	* See COPYRIGHT.txt and LICENSE.txt.
9	*
10	* This code is distributed in the hope that it will be useful,
11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	* GNU General Public License for more details.
14	*
15	* This header and all notices must be kept intact.
16	*
17	* @author Karim Rahimpur
18	* @package groups
19	* @since groups 4.0.0
20	*/
21
22	if ( !defined( 'ABSPATH' ) ) {
23	exit;
24	}
25
26	//phpcs:disable WordPress.WP.AlternativeFunctions.file_system_operations_fclose, WordPress.WP.AlternativeFunctions.file_system_operations_fopen, WordPress.Security.EscapeOutput.ExceptionNotEscaped
27
28	/**
29	* Lock.
30	*/
31	class Groups_Lock {
32
33	/**
34	* @var int
35	*/
36	const TIMEOUT_DEFAULT = 1000000;
37
38	/**
39	* @var int
40	*/
41	const SLEEP_DEFAULT = 10000;
42
43	/**
44	* @var int
45	*/
46	const AUX_TIMEOUT = 2;
47
48	/**
49	* Lockfile path.
50	*
51	* @var string
52	*/
53	private $path = null;
54
55	/**
56	* Lock file pointer.
57	*
58	* @var resource
59	*/
60	private $h = null;
61
62	/**
63	* Timeout microseconds.
64	*
65	* @var int
66	*/
67	private $timeout = self::TIMEOUT_DEFAULT;
68
69	/**
70	* Sleep microseconds.
71	*
72	* @var integer
73	*/
74	private $sleep = self::SLEEP_DEFAULT;
75
76	/**
77	* Create an instance.
78	*
79	* @throws Groups_Lock_Exception
80	*
81	* @param string $name lock name, generic lock used by default
82	* @param int $timeout lock timeout in microseconds, default used when null, 0 is blocking
83	*/
84	public function __construct( $name = null, $timeout = null ) {
85	if (
86	function_exists( 'fopen' ) &&
87	function_exists( 'flock' ) &&
88	function_exists( 'fclose' ) &&
89	function_exists( 'is_readable' )
90	) {
91
92	if ( $name !== null ) {
93	$name = trim( sanitize_key( $name ) );
94	} else {
95	$name = 'groups-lock';
96	}
97	$blog_id = intval( get_current_blog_id() );
98	$path = sprintf(
99	'%s%s.%s-%d',
100	untrailingslashit( WP_CONTENT_DIR ),
101	DIRECTORY_SEPARATOR,
102	$name,
103	$blog_id
104	);
105	/**
106	* Modify the lock file path.
107	*
108	* @param string $path
109	* @param string $name
110	* @param int $blog_id
111	*
112	* @return string
113	*/
114	$path = apply_filters( 'groups_lock_path', $path, $name, $blog_id );
115
116	if ( $timeout !== null && is_numeric( $timeout ) ) {
117	$this->timeout = max( 0, intval( $timeout ) );
118	}
119
120	/**
121	* Modify the lock timeout (microseconds).
122	*
123	* @param int $timeout
124	* @param string $name
125	* @param int $blog_id
126	*
127	* @return int
128	*/
129	$this->timeout = apply_filters( 'groups_lock_timeout', $this->timeout, $name, $blog_id );
130	if ( is_numeric( $this->timeout ) ) {
131	$this->timeout = max( 0, intval( $this->timeout ) );
132	} else {
133	$this->timeout = 0;
134	}
135
136	/**
137	* Modify the lock sleep gap (microseconds).
138	*
139	* @param int $sleep
140	* @param string $name
141	* @param int $blog_id
142	*
143	* @return int
144	*/
145	$this->sleep = apply_filters( 'groups_lock_sleep', $this->sleep, $name, $blog_id );
146	if ( is_numeric( $this->sleep ) ) {
147	$this->sleep = max( 1, intval( $this->sleep ) );
148	} else {
149	$this->sleep = self::SLEEP_DEFAULT;
150	}
151
152	if ( is_string( $path ) ) {
153	$h = @fopen( $path, 'c' );
154	if ( $h !== false ) {
155	$this->path = $path;
156	@fclose( $h );
157	} else {
158	$error = error_get_last();
159	$msg = $error !== null && !empty( $error['message'] ) ? $error['message'] : '';
160	if ( !file_exists( $path ) ) {
161	$error = sprintf( 'Failed to create lock %s [%s]', $path, $msg );
162	} else {
163	$error = sprintf( 'Failed to access lock %s [%s]', $path, $msg );
164	}
165	throw new Groups_Lock_Exception( $error );
166	}
167	}
168	register_shutdown_function( array( $this, 'release' ) );
169	} else {
170	throw new Groups_Lock_Exception( 'Lock requires fopen, flock, fclose, is_readable' );
171	}
172	}
173
174	/**
175	* Lock is usable.
176	*
177	* @return boolean
178	*/
179	public function is_usable() {
180	return $this->path !== null && is_readable( $this->path );
181	}
182
183	/**
184	* Lock is locked.
185	*
186	* @since 4.3.0
187	*
188	* @return boolean
189	*/
190	public function is_locked() {
191	return $this->h !== null;
192	}
193
194	/**
195	* Write lock.
196	*
197	* @throws Groups_Lock_Exception
198	*
199	* @return boolean
200	*/
201	public function writer() {
202	if ( $this->path !== null ) {
203	if ( $this->h === null ) {
204	$h = @fopen( $this->path, 'r+' );
205	if ( $h !== false ) {
206	if ( $this->timeout === 0 ) {
207	// blocking
208	if ( @flock( $h, LOCK_EX ) ) {
209	$this->h = $h;
210	}
211	} else {
212	// non-blocking
213	if ( function_exists( 'microtime' ) && function_exists( 'usleep' ) ) {
214	$t = microtime( true ) * 1000000;
215	while ( $this->h === null && ( microtime( true ) * 1000000 - $t < $this->timeout ) ) {
216	if ( @flock( $h, LOCK_EX \| LOCK_NB ) ) {
217	$this->h = $h;
218	break;
219	} else {
220	usleep( $this->sleep );
221	}
222	}
223	} else {
224	// fallback if required functions missing
225	$t = time();
226	while ( $this->h === null && ( time() - $t < self::AUX_TIMEOUT ) ) {
227	if ( @flock( $h, LOCK_EX \| LOCK_NB ) ) {
228	$this->h = $h;
229	break;
230	} else {
231	sleep( 1 );
232	}
233	}
234	}
235	}
236	if ( $this->h === null ) {
237	throw new Groups_Lock_Exception( sprintf( 'Failed to obtain write lock %s', $this->path ) );
238	}
239	} else {
240	throw new Groups_Lock_Exception( sprintf( 'Failed to access write lock %s ', $this->path ) );
241	}
242	}
243	}
244	return $this->h !== null;
245	}
246
247	/**
248	* Read lock.
249	*
250	* @throws Groups_Lock_Exception
251	*
252	* @return boolean
253	*/
254	public function reader() {
255	if ( $this->path !== null ) {
256	if ( $this->h === null ) {
257	$h = @fopen( $this->path, 'r' );
258	if ( $h !== false ) {
259	if ( $this->timeout === 0 ) {
260	// blocking
261	if ( @flock( $h, LOCK_SH ) ) {
262	$this->h = $h;
263	}
264	} else {
265	// non
266	if ( function_exists( 'microtime' ) && function_exists( 'usleep' ) ) {
267	$t = microtime( true ) * 1000000;
268	while ( $this->h === null && ( microtime( true ) * 1000000 - $t < $this->timeout ) ) {
269	if ( @flock( $h, LOCK_SH \| LOCK_NB ) ) {
270	$this->h = $h;
271	break;
272	} else {
273	usleep( $this->sleep );
274	}
275	}
276	} else {
277	// fallback
278	$t = time();
279	while ( $this->h === null && ( time() - $t < self::AUX_TIMEOUT ) ) {
280	if ( @flock( $h, LOCK_SH \| LOCK_NB ) ) {
281	$this->h = $h;
282	break;
283	} else {
284	sleep( 1 );
285	}
286	}
287	}
288	}
289	if ( $this->h === null ) {
290	throw new Groups_Lock_Exception( sprintf( 'Failed to obtain read lock %s', $this->path ) );
291	}
292	} else {
293	throw new Groups_Lock_Exception( sprintf( 'Failed to access read lock %s', $this->path ) );
294	}
295	}
296	}
297	return $this->h !== null;
298	}
299
300	/**
301	* Release lock.
302	*
303	* @return boolean
304	*/
305	public function release() {
306	$released = false;
307	if ( $this->h !== null ) {
308	$released = @flock( $this->h, LOCK_UN );
309	@fclose( $this->h );
310	$this->h = null;
311	}
312	return $released;
313	}
314	}
315