MultipleStoreLocker::lockAndCheckQuorumAndTtlOnAllStores() - Code Metrics - remi-san/lock - Measure and Improve Code Quality continuously with Scrutinizer

lockAndCheckQuorumAndTtlOnAllStores() A
last analyzed 2016-09-01 09:34 UTC

↳ Parent: MultipleStoreLocker

Complexity

Conditions	2
Paths	2

Size

Total Lines	15
Code Lines	9

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	10
CRAP Score	2

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
c	1
b	0
f	0
dl	0
loc	15
ccs	10
cts	10
cp	1
rs	9.4285
cc	2
eloc	9
nc	2
nop	2
crap	2

<?php

namespace RemiSan\Lock\Locker;

use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerAwareTrait;
use Psr\Log\NullLogger;
use RemiSan\Lock\Exceptions\LockingException;
use RemiSan\Lock\Exceptions\UnlockingException;
use RemiSan\Lock\Lock;
use RemiSan\Lock\Locker;
use RemiSan\Lock\LockStore;
use RemiSan\Lock\Quorum;
use RemiSan\Lock\TokenGenerator;
use Symfony\Component\Stopwatch\Stopwatch;

final class MultipleStoreLocker implements Locker, LoggerAwareInterface
{
    use LoggerAwareTrait;

    /** @var LockStore[] */
    private $stores = [];

    /** @var TokenGenerator */
    private $tokenGenerator;

    /** @var Quorum */
    private $quorum;

    /** @var Stopwatch */
    private $stopwatch;

    /**
     * MultipleStoreLocker constructor.
     *
     * @param LockStore[]    $stores         Array of persistence stores for the locks
     * @param TokenGenerator $tokenGenerator The token generator
     * @param Quorum         $quorum         The quorum implementation to use
     * @param Stopwatch      $stopwatch      A way to measure time passed
     */
    public function __construct(
        array $stores,
        TokenGenerator $tokenGenerator,
        Quorum $quorum,
        Stopwatch $stopwatch
    ) {
        $this->setStores($stores);
        $this->setQuorum($quorum);

        $this->tokenGenerator = $tokenGenerator;
        $this->stopwatch = $stopwatch;

        $this->logger = new NullLogger();
    }

    /**
     * {@inheritdoc}
     */
    public function lock($resource, $ttl = null, $retryDelay = 0, $retryCount = 0)
    {
        $lock = new Lock((string) $resource, $this->tokenGenerator->generateToken());

        $tried = 0;
        while (true) {
            try {
                return $this->lockAndCheckQuorumAndTtlOnAllStores($lock, $ttl);
            } catch (LockingException $e) {
                $this->logger->notice($e->getMessage(), ['resource' => $lock->getResource()]);
                $this->resetLock($lock);
            }

            if ($tried++ === $retryCount) {
                break;
            }

            $this->waitBeforeRetrying($retryDelay);
        }

        throw new LockingException('Failed locking the resource.');
    }

    /**
     * {@inheritdoc}
     */
    public function isLocked($resource)
    {
        foreach ($this->stores as $store) {
            if ($store->exists((string) $resource)) {
                return true;
            }
        }

        return false;
    }

    /**
     * {@inheritdoc}
     */
    public function unlock(Lock $lock)
    {
        foreach ($this->stores as $store) {
            if (!$store->delete($lock)) {
                if ($store->exists($lock->getResource())) {
                    // Only throw an exception if the lock is still present
                    throw new UnlockingException('Failed releasing the lock.');
                }
            }
        }
    }

    /**
     * Try locking resource on all stores.
     *
     * Measure the time to do it and reject if not enough stores have successfully
     * locked the resource or if time to lock on all stores have exceeded the ttl.
     *
     * @param Lock $lock The lock instance
     * @param int  $ttl  Time to live in milliseconds
     *
     * @throws LockingException
     *
     * @return Lock
     */
    private function lockAndCheckQuorumAndTtlOnAllStores(Lock $lock, $ttl)
    {
        $timeMeasure = $this->stopwatch->start($lock->getToken());
        $storesLocked = $this->lockOnAllStores($lock, $ttl);
        $timeMeasure->stop();

        $this->checkQuorum($storesLocked);

        if ($ttl) {
            $this->checkTtl($timeMeasure->getDuration(), $ttl);
            $lock->setValidityEndTime($timeMeasure->getOrigin() + $ttl);
        }

        return $lock;
    }

    /**
     * Lock resource on all stores and count how many stores did it with success.
     *
     * @param Lock $lock The lock instance
     * @param int  $ttl  Time to live in milliseconds
     *
     * @return int The number of stores on which the resource has been locked
     */
    private function lockOnAllStores(Lock $lock, $ttl)
    {
        $storesLocked = 0;

        foreach ($this->stores as $store) {
            if ($store->set($lock, $ttl)) {
                ++$storesLocked;
            }
        }

        return $storesLocked;
    }

    /**
     * Unlock the resource on all stores.
     *
     * @param Lock $lock The lock to release
     */
    private function resetLock($lock)
    {
        foreach ($this->stores as $store) {
            $store->delete($lock);
        }
    }

    /**
     * Init all stores passed to the constructor.
     *
     * If no store is given, it will return an InvalidArgumentException.
     *
     * @param LockStore[] $stores The lock stores
     *
     * @throws \InvalidArgumentException
     */
    private function setStores(array $stores)
    {
        if (count($stores) === 0) {
            throw new \InvalidArgumentException('You must provide at least one LockStore.');
        }

        $this->stores = $stores;
    }

    /**
     * Set the quorum based on the number of stores passed to the constructor.
     *
     * @param Quorum $quorum The quorum implementation to use
     */
    private function setQuorum(Quorum $quorum)
    {
        $this->quorum = $quorum;
        $this->quorum->init(count($this->stores));
    }

    /**
     * Check if the number of stores where the resource has been locked meet the quorum.
     *
     * @param int $storesLocked The number of stores on which the resource has been locked
     *
     * @throws LockingException
     */
    private function checkQuorum($storesLocked)
    {
        if (!$this->quorum->isMet($storesLocked)) {
            throw new LockingException('Quorum has not been met.');
        }
    }

    /**
     * Make the script wait before retrying to lock.
     *
     * @param int $retryDelay The retry delay in milliseconds
     */
    private function waitBeforeRetrying($retryDelay)
    {
        usleep($retryDelay * 1000);
    }

    /**
     * Checks if the elapsed time is inferior to the ttl.
     *
     * To the elapsed time is added a drift time to have a margin of error.
     * If this adjusted time is greater than the ttl, it will throw a LockingException.
     *
     * @param int $elapsedTime The time elapsed in milliseconds
     * @param int $ttl         The time to live in milliseconds
     *
     * @throws LockingException
     */
    private function checkTtl($elapsedTime, $ttl)
    {
        $adjustedElapsedTime = ($elapsedTime + $this->getDrift($ttl));

        if ($adjustedElapsedTime >= $ttl) {
            throw new LockingException('Time to lock the resource has exceeded the ttl.');
        }
    }

    /**
     * Get the drift time based on ttl in ms.
     *
     * Return the max drift time of all stores
     *
     * @param int $ttl The time to live in milliseconds
     *
     * @return float
     */
    private function getDrift($ttl)
    {
        return max(array_map(function (LockStore $store) use ($ttl) {
            return $store->getDrift($ttl);
        }, $this->stores));
    }
}


1		<?php
2
3		namespace RemiSan\Lock\Locker;
4
5		use Psr\Log\LoggerAwareInterface;
6		use Psr\Log\LoggerAwareTrait;
7		use Psr\Log\NullLogger;
8		use RemiSan\Lock\Exceptions\LockingException;
9		use RemiSan\Lock\Exceptions\UnlockingException;
10		use RemiSan\Lock\Lock;
11		use RemiSan\Lock\Locker;
12		use RemiSan\Lock\LockStore;
13		use RemiSan\Lock\Quorum;
14		use RemiSan\Lock\TokenGenerator;
15		use Symfony\Component\Stopwatch\Stopwatch;
16
17		final class MultipleStoreLocker implements Locker, LoggerAwareInterface
18		{
19		use LoggerAwareTrait;
20
21		/** @var LockStore[] */
22		private $stores = [];
23
24		/** @var TokenGenerator */
25		private $tokenGenerator;
26
27		/** @var Quorum */
28		private $quorum;
29
30		/** @var Stopwatch */
31		private $stopwatch;
32
33		/**
34		* MultipleStoreLocker constructor.
35		*
36		* @param LockStore[] $stores Array of persistence stores for the locks
37		* @param TokenGenerator $tokenGenerator The token generator
38		* @param Quorum $quorum The quorum implementation to use
39		* @param Stopwatch $stopwatch A way to measure time passed
40		*/
41	36	public function __construct(
42		array $stores,
43		TokenGenerator $tokenGenerator,
44		Quorum $quorum,
45		Stopwatch $stopwatch
46		) {
47	36	$this->setStores($stores);
48	36	$this->setQuorum($quorum);
49
50	36	$this->tokenGenerator = $tokenGenerator;
51	36	$this->stopwatch = $stopwatch;
52
53	36	$this->logger = new NullLogger();
54	36	}
55
56		/**
57		* {@inheritdoc}
58		*/
59	12	public function lock($resource, $ttl = null, $retryDelay = 0, $retryCount = 0)
60		{
61	12	$lock = new Lock((string) $resource, $this->tokenGenerator->generateToken());
62
63	12	$tried = 0;
64	12	while (true) {
65		try {
66	12	return $this->lockAndCheckQuorumAndTtlOnAllStores($lock, $ttl);
67	6	} catch (LockingException $e) {
68	6	$this->logger->notice($e->getMessage(), ['resource' => $lock->getResource()]);
69	6	$this->resetLock($lock);
70		}
71
72	6	if ($tried++ === $retryCount) {
73	6	break;
74		}
75
76	6	$this->waitBeforeRetrying($retryDelay);
77	4	}
78
79	6	throw new LockingException('Failed locking the resource.');
80		}
81
82		/**
83		* {@inheritdoc}
84		*/
85	9	public function isLocked($resource)
86		{
87	9	foreach ($this->stores as $store) {
88	9	if ($store->exists((string) $resource)) {
89	7	return true;
90		}
91	4	}
92
93	3	return false;
94		}
95
96		/**
97		* {@inheritdoc}
98		*/
99	12	public function unlock(Lock $lock)
100		{
101	12	foreach ($this->stores as $store) {
102	12	if (!$store->delete($lock)) {
103	9	if ($store->exists($lock->getResource())) {
104		// Only throw an exception if the lock is still present
105	8	throw new UnlockingException('Failed releasing the lock.');
106		}
107	2	}
108	6	}
109	6	}
110
111		/**
112		* Try locking resource on all stores.
113		*
114		* Measure the time to do it and reject if not enough stores have successfully
115		* locked the resource or if time to lock on all stores have exceeded the ttl.
116		*
117		* @param Lock $lock The lock instance
118		* @param int $ttl Time to live in milliseconds
119		*
120		* @throws LockingException
121		*
122		* @return Lock
123		*/
124	12	private function lockAndCheckQuorumAndTtlOnAllStores(Lock $lock, $ttl)
125		{
126	12	$timeMeasure = $this->stopwatch->start($lock->getToken());
127	12	$storesLocked = $this->lockOnAllStores($lock, $ttl);
128	12	$timeMeasure->stop();
129
130	12	$this->checkQuorum($storesLocked);
131
132	9	if ($ttl) {
133	6	$this->checkTtl($timeMeasure->getDuration(), $ttl);
134	3	$lock->setValidityEndTime($timeMeasure->getOrigin() + $ttl);
135	2	}
136
137	6	return $lock;
138		}
139
140		/**
141		* Lock resource on all stores and count how many stores did it with success.
142		*
143		* @param Lock $lock The lock instance
144		* @param int $ttl Time to live in milliseconds
145		*
146		* @return int The number of stores on which the resource has been locked
147		*/
148	12	private function lockOnAllStores(Lock $lock, $ttl)
149		{
150	12	$storesLocked = 0;
151
152	12	foreach ($this->stores as $store) {
153	12	if ($store->set($lock, $ttl)) {
154	12	++$storesLocked;
155	8	}
156	8	}
157
158	12	return $storesLocked;
159		}
160
161		/**
162		* Unlock the resource on all stores.
163		*
164		* @param Lock $lock The lock to release
165		*/
166	6	private function resetLock($lock)
167		{
168	6	foreach ($this->stores as $store) {
169	6	$store->delete($lock);
170	4	}
171	6	}
172
173		/**
174		* Init all stores passed to the constructor.
175		*
176		* If no store is given, it will return an InvalidArgumentException.
177		*
178		* @param LockStore[] $stores The lock stores
179		*
180		* @throws \InvalidArgumentException
181		*/
182	36	private function setStores(array $stores)
183		{
184	36	if (count($stores) === 0) {
185	3	throw new \InvalidArgumentException('You must provide at least one LockStore.');
186		}
187
188	36	$this->stores = $stores;
189	36	}
190
191		/**
192		* Set the quorum based on the number of stores passed to the constructor.
193		*
194		* @param Quorum $quorum The quorum implementation to use
195		*/
196	36	private function setQuorum(Quorum $quorum)
197		{
198	36	$this->quorum = $quorum;
199	36	$this->quorum->init(count($this->stores));
200	36	}
201
202		/**
203		* Check if the number of stores where the resource has been locked meet the quorum.
204		*
205		* @param int $storesLocked The number of stores on which the resource has been locked
206		*
207		* @throws LockingException
208		*/
209	12	private function checkQuorum($storesLocked)
210		{
211	12	if (!$this->quorum->isMet($storesLocked)) {
212	3	throw new LockingException('Quorum has not been met.');
213		}
214	9	}
215
216		/**
217		* Make the script wait before retrying to lock.
218		*
219		* @param int $retryDelay The retry delay in milliseconds
220		*/
221	6	private function waitBeforeRetrying($retryDelay)
222		{
223	6	usleep($retryDelay * 1000);
224	6	}
225
226		/**
227		* Checks if the elapsed time is inferior to the ttl.
228		*
229		* To the elapsed time is added a drift time to have a margin of error.
230		* If this adjusted time is greater than the ttl, it will throw a LockingException.
231		*
232		* @param int $elapsedTime The time elapsed in milliseconds
233		* @param int $ttl The time to live in milliseconds
234		*
235		* @throws LockingException
236		*/
237	6	private function checkTtl($elapsedTime, $ttl)
238		{
239	6	$adjustedElapsedTime = ($elapsedTime + $this->getDrift($ttl));
240
241	6	if ($adjustedElapsedTime >= $ttl) {
242	3	throw new LockingException('Time to lock the resource has exceeded the ttl.');
243		}
244	3	}
245
246		/**
247		* Get the drift time based on ttl in ms.
248		*
249		* Return the max drift time of all stores
250		*
251		* @param int $ttl The time to live in milliseconds
252		*
253		* @return float
254		*/
255		private function getDrift($ttl)
256		{
257	6	return max(array_map(function (LockStore $store) use ($ttl) {
258	6	return $store->getDrift($ttl);
259	6	}, $this->stores));
260		}
261		}
262

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lockAndCheckQuorumAndTtlOnAllStores() A last analyzed 2016-09-01 09:34 UTC

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lockAndCheckQuorumAndTtlOnAllStores() A
last analyzed 2016-09-01 09:34 UTC