gmail-smtp / google-api-php-client / vendor / google / auth / src / Cache / SysVCacheItemPool.php

SysVCacheItemPool.php in Gmail SMTP trunk, at google-api-php-client/vendor/google/auth/src/Cache/SysVCacheItemPool.php

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1	<?php
2	/**
3	* Copyright 2018 Google Inc. All Rights Reserved.
4	*
5	* Licensed under the Apache License, Version 2.0 (the "License");
6	* you may not use this file except in compliance with the License.
7	* You may obtain a copy of the License at
8	*
9	* http://www.apache.org/licenses/LICENSE-2.0
10	*
11	* Unless required by applicable law or agreed to in writing, software
12	* distributed under the License is distributed on an "AS IS" BASIS,
13	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14	* See the License for the specific language governing permissions and
15	* limitations under the License.
16	*/
17	namespace Google\Auth\Cache;
18
19	use Psr\Cache\CacheItemInterface;
20	use Psr\Cache\CacheItemPoolInterface;
21	use SysvSemaphore;
22	use SysvSharedMemory;
23
24	/**
25	* SystemV shared memory based CacheItemPool implementation.
26	*
27	* This CacheItemPool implementation can be used among multiple processes, but
28	* it doesn't provide any locking mechanism. If multiple processes write to
29	* this ItemPool, you have to avoid race condition manually in your code.
30	*/
31	class SysVCacheItemPool implements CacheItemPoolInterface
32	{
33	const VAR_KEY = 1;
34
35	const DEFAULT_PROJ = 'A';
36
37	const DEFAULT_SEM_PROJ = 'B';
38
39	const DEFAULT_MEMSIZE = 100000;
40
41	const DEFAULT_PERM = 0600;
42
43	/**
44	* @var int
45	*/
46	private $sysvKey;
47
48	/**
49	* @var CacheItemInterface[]
50	*/
51	private $items;
52
53	/**
54	* @var CacheItemInterface[]
55	*/
56	private $deferredItems;
57
58	/**
59	* @var array<mixed>
60	*/
61	private $options;
62
63	/**
64	* @var bool
65	*/
66	private $hasLoadedItems = false;
67
68	/**
69	* @var SysvSemaphore\|false
70	*/
71	private SysvSemaphore\|false $semId = false;
72
73	/**
74	* Maintain the process which is currently holding the semaphore to prevent deadlock.
75	*
76	* @var int\|null
77	*/
78	private ?int $lockOwnerPid = null;
79
80	/**
81	* Create a SystemV shared memory based CacheItemPool.
82	*
83	* @param array<mixed> $options {
84	* [optional] Configuration options.
85	*
86	* @type int $variableKey The variable key for getting the data from the shared memory. Defaults to 1.
87	* @type string $proj The project identifier for ftok. This needs to be a one character string.
88	* Defaults to 'A'.
89	* @type string $semProj The project identifier for ftok to provide to `sem_get`. This needs to be a one
90	* character string.
91	* Defaults to 'B'.
92	* @type int $memsize The memory size in bytes for shm_attach. Defaults to 10000.
93	* @type int $perm The permission for shm_attach. Defaults to 0600.
94	* }
95	*/
96	public function __construct($options = [])
97	{
98	if (!extension_loaded('sysvshm')) {
99	throw new \RuntimeException(
100	'sysvshm extension is required to use this ItemPool'
101	);
102	}
103	$this->options = $options + [
104	'variableKey' => self::VAR_KEY,
105	'proj' => self::DEFAULT_PROJ,
106	'semProj' => self::DEFAULT_SEM_PROJ,
107	'memsize' => self::DEFAULT_MEMSIZE,
108	'perm' => self::DEFAULT_PERM
109	];
110	$this->items = [];
111	$this->deferredItems = [];
112	$this->sysvKey = ftok(__FILE__, $this->options['proj']);
113
114	// gracefully handle when `sysvsem` isn't loaded
115	// @TODO(v2): throw an exception when the extension isn't loaded
116	if (extension_loaded('sysvsem')) {
117	$semKey = ftok(__FILE__, $this->options['semProj']);
118	$this->semId = sem_get($semKey, 1, $this->options['perm'], true);
119	}
120	}
121
122	/**
123	* @param mixed $key
124	* @return CacheItemInterface
125	*/
126	public function getItem($key): CacheItemInterface
127	{
128	$this->loadItems();
129	return current($this->getItems([$key])); // @phpstan-ignore-line
130	}
131
132	/**
133	* @param array<mixed> $keys
134	* @return iterable<CacheItemInterface>
135	*/
136	public function getItems(array $keys = []): iterable
137	{
138	$this->loadItems();
139	$items = [];
140	foreach ($keys as $key) {
141	$items[$key] = $this->hasItem($key) ?
142	clone $this->items[$key] :
143	new TypedItem($key);
144	}
145	return $items;
146	}
147
148	/**
149	* {@inheritdoc}
150	*/
151	public function hasItem($key): bool
152	{
153	$this->loadItems();
154	return isset($this->items[$key]) && $this->items[$key]->isHit();
155	}
156
157	/**
158	* {@inheritdoc}
159	*/
160	public function clear(): bool
161	{
162	if (!$this->acquireLock()) {
163	return false;
164	}
165
166	$this->items = [];
167	$this->deferredItems = [];
168	$ret = $this->saveCurrentItems();
169
170	$this->resetShm();
171	$this->releaseLock();
172	return $ret;
173	}
174
175	/**
176	* {@inheritdoc}
177	*/
178	public function deleteItem($key): bool
179	{
180	return $this->deleteItems([$key]);
181	}
182
183	/**
184	* {@inheritdoc}
185	*/
186	public function deleteItems(array $keys): bool
187	{
188	if (!$this->acquireLock()) {
189	return false;
190	}
191
192	if (!$this->hasLoadedItems) {
193	$this->loadItems();
194	}
195
196	foreach ($keys as $key) {
197	unset($this->items[$key]);
198	}
199	$ret = $this->saveCurrentItems();
200
201	$this->resetShm();
202	$this->releaseLock();
203	return $ret;
204	}
205
206	/**
207	* {@inheritdoc}
208	*/
209	public function save(CacheItemInterface $item): bool
210	{
211	if (!$this->acquireLock()) {
212	return false;
213	}
214
215	if (!$this->hasLoadedItems) {
216	$this->loadItems();
217	}
218
219	$this->items[$item->getKey()] = $item;
220	$ret = $this->saveCurrentItems();
221	$this->releaseLock();
222	return $ret;
223	}
224
225	/**
226	* {@inheritdoc}
227	*/
228	public function saveDeferred(CacheItemInterface $item): bool
229	{
230	$this->deferredItems[$item->getKey()] = $item;
231	return true;
232	}
233
234	/**
235	* {@inheritdoc}
236	*/
237	public function commit(): bool
238	{
239	if (!$this->acquireLock()) {
240	return false;
241	}
242
243	foreach ($this->deferredItems as $item) {
244	if ($this->save($item) === false) {
245	$this->releaseLock();
246	return false;
247	}
248	}
249	$this->deferredItems = [];
250	$this->releaseLock();
251	return true;
252	}
253
254	/**
255	* Save the current items.
256	*
257	* @return bool true when success, false upon failure
258	*/
259	private function saveCurrentItems()
260	{
261	if (!$this->acquireLock()) {
262	return false;
263	}
264
265	if (false !== $shmid = $this->attachShm()) {
266	$success = shm_put_var(
267	$shmid,
268	$this->options['variableKey'],
269	$this->items
270	);
271	shm_detach($shmid);
272	$this->releaseLock();
273	return $success;
274	}
275	$this->releaseLock();
276	return false;
277	}
278
279	/**
280	* Load the items from the shared memory.
281	*
282	* @return bool true when success, false upon failure
283	*/
284	private function loadItems()
285	{
286	if (!$this->acquireLock()) {
287	return false;
288	}
289
290	if (false !== $shmid = $this->attachShm()) {
291	$data = @shm_get_var($shmid, $this->options['variableKey']);
292	$this->items = $data ?: [];
293	shm_detach($shmid);
294	$this->hasLoadedItems = true;
295	$this->releaseLock();
296	return true;
297	}
298	$this->releaseLock();
299	return false;
300	}
301
302	private function acquireLock(): bool
303	{
304	if ($this->semId === false) {
305	// if `sysvsem` isn't loaded, or if `sem_get` fails, return true
306	// this ensures BC with previous versions of the auth library.
307	// @TODO consider better handling when `sem_get` fails.
308	return true;
309	}
310
311	$currentPid = getmypid();
312	if ($this->lockOwnerPid === $currentPid) {
313	// We already have the lock
314	return true;
315	}
316
317	if (sem_acquire($this->semId)) {
318	$this->lockOwnerPid = (int) $currentPid;
319	return true;
320	}
321	return false;
322	}
323
324	private function releaseLock(): bool
325	{
326	if ($this->semId === false \|\| $this->lockOwnerPid !== getmypid()) {
327	return true;
328	}
329
330	$this->lockOwnerPid = null;
331	return sem_release($this->semId);
332	}
333
334	private function resetShm(): void
335	{
336	// Remove the shared memory segment and semaphore when clearing the cache
337	$shmid = @shm_attach($this->sysvKey);
338	if ($shmid !== false) {
339	@shm_remove($shmid);
340	@shm_detach($shmid);
341	}
342	}
343
344	private function attachShm(): SysvSharedMemory\|false
345	{
346	return shm_attach(
347	$this->sysvKey,
348	$this->options['memsize'],
349	$this->options['perm']
350	);
351	}
352	}
353