decalog / includes / libraries / lock / util / PcntlTimeout.php

PcntlTimeout.php in DecaLog 4.4.0, at includes/libraries/lock/util/PcntlTimeout.php

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1	<?php
2
3	declare(strict_types=1);
4
5	namespace malkusch\lock\util;
6
7	use InvalidArgumentException;
8	use malkusch\lock\exception\DeadlineException;
9	use malkusch\lock\exception\LockAcquireException;
10	use RuntimeException;
11
12	/**
13	* Timeout based on a scheduled alarm.
14	*
15	* This class requires the pcntl module.
16	*
17	* @author Markus Malkusch <[email protected]>
18	* @link bitcoin:1335STSwu9hST4vcMRppEPgENMHD2r1REK Donations
19	* @license WTFPL
20	* @internal
21	*/
22	final class PcntlTimeout
23	{
24	/**
25	* @var int Timeout in seconds
26	*/
27	private $timeout;
28
29	/**
30	* Builds the timeout.
31	*
32	* @param int $timeout Timeout in seconds.
33	* @throws \RuntimeException When the PCNTL module is not enabled.
34	* @throws \InvalidArgumentException When the timeout is zero or negative.
35	*/
36	public function __construct(int $timeout)
37	{
38	if (!self::isSupported()) {
39	throw new RuntimeException('PCNTL module not enabled');
40	}
41
42	if ($timeout <= 0) {
43	throw new InvalidArgumentException(
44	'Timeout must be positive and non zero'
45	);
46	}
47
48	$this->timeout = $timeout;
49	}
50
51	/**
52	* Runs the code and would eventually time out.
53	*
54	* This method has the side effect, that any signal handler for SIGALRM will
55	* be reset to the default hanlder (SIG_DFL). It also expects that there is
56	* no previously scheduled alarm. If your application uses alarms
57	* ({@link pcntl_alarm()}) or a signal handler for SIGALRM, don't use this
58	* method. It will interfer with your application and lead to unexpected
59	* behaviour.
60	*
61	* @param callable $code Executed code block
62	* @throws \malkusch\lock\exception\DeadlineException Running the code hit
63	* the deadline.
64	* @throws \malkusch\lock\exception\LockAcquireException Installing the
65	* timeout failed.
66	* @return mixed Return value of the executed block
67	*/
68	public function timeBoxed(callable $code)
69	{
70	$existingHandler = pcntl_signal_get_handler(SIGALRM);
71
72	$signal = pcntl_signal(SIGALRM, function (): void {
73	throw new DeadlineException(sprintf(
74	'Timebox hit deadline of %d seconds',
75	$this->timeout
76	));
77	});
78	if (!$signal) {
79	throw new LockAcquireException('Could not install signal');
80	}
81
82	$oldAlarm = pcntl_alarm($this->timeout);
83	if ($oldAlarm != 0) {
84	throw new LockAcquireException('Existing alarm was not expected');
85	}
86
87	try {
88	return $code();
89	} finally {
90	pcntl_alarm(0);
91	pcntl_signal_dispatch();
92	pcntl_signal(SIGALRM, $existingHandler);
93	}
94	}
95
96	/**
97	* Returns if this class is supported by the PHP runtime.
98	*
99	* This class requires the pcntl module. This method checks if
100	* it is available.
101	*
102	* @return bool TRUE if this class is supported by the PHP runtime.
103	*/
104	public static function isSupported(): bool
105	{
106	return
107	PHP_SAPI === 'cli' &&
108	extension_loaded('pcntl') &&
109	function_exists('pcntl_alarm') &&
110	function_exists('pcntl_signal') &&
111	function_exists('pcntl_signal_dispatch');
112	}
113	}
114