MultipleStoreLocker::isLocked() - Code Metrics - Inspection of "Changes in naming and refactoring" - remi-san/lock - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( ef434c...056009 )

by Rémi

created 2016-09-01 08:17 UTC

MultipleStoreLocker::isLocked() A

↳ Parent: MultipleStoreLocker

Complexity

Conditions	3
Paths	3

Size

Total Lines	10
Code Lines	5

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	6
CRAP Score	3

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
c	1
b	0
f	0
dl	0
loc	10
ccs	6
cts	6
cp	1
rs	9.4285
cc	3
eloc	5
nc	3
nop	1
crap	3

<?php

namespace RemiSan\Lock\Locker;

use RemiSan\Lock\LockStore;
use RemiSan\Lock\Exceptions\LockingException;
use RemiSan\Lock\Exceptions\UnlockingException;
use RemiSan\Lock\Lock;
use RemiSan\Lock\Locker;
use RemiSan\Lock\Quorum;
use RemiSan\Lock\TokenGenerator;
use Symfony\Component\Stopwatch\Stopwatch;

final class MultipleStoreLocker implements Locker
{
    /** @var LockStore[] */
    private $stores = [];

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

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

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

    /**
     * RedLock constructor.
     *
     * @param LockStore[]    $stores         Array of persistence system connections
     * @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;
    }

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

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MultipleStoreLocker::isLocked() A

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