LockBackend
6 months ago
DistributedList.php
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Lock.php
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LockBackend.php
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Lock.php
190 lines
| 1 | <?php |
| 2 | |
| 3 | /** |
| 4 | * Matomo - free/libre analytics platform |
| 5 | * |
| 6 | * @link https://matomo.org |
| 7 | * @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later |
| 8 | */ |
| 9 | namespace Piwik\Concurrency; |
| 10 | |
| 11 | use Piwik\Common; |
| 12 | use Piwik\Date; |
| 13 | class Lock |
| 14 | { |
| 15 | public const MAX_KEY_LEN = 70; |
| 16 | public const DEFAULT_TTL = 60; |
| 17 | /** |
| 18 | * @var LockBackend |
| 19 | */ |
| 20 | private $backend; |
| 21 | private $namespace; |
| 22 | private $lockKey = null; |
| 23 | private $lockValue = null; |
| 24 | private $defaultTtl = null; |
| 25 | private $lastAcquireTime = null; |
| 26 | /** |
| 27 | * @param string $namespace |
| 28 | * @param int|null $defaultTtl defaults to {@link self::DEFAULT_TTL} |
| 29 | */ |
| 30 | public function __construct(\Piwik\Concurrency\LockBackend $backend, $namespace, $defaultTtl = null) |
| 31 | { |
| 32 | if (mb_strlen($namespace) > self::MAX_KEY_LEN - 32) { |
| 33 | // A longer namespace could be cut off for too long ids, so we don't support it |
| 34 | throw new \InvalidArgumentException('Lock namespace must be shorter than ' . (self::MAX_KEY_LEN - 32) . ' chars'); |
| 35 | } |
| 36 | $this->backend = $backend; |
| 37 | $this->namespace = $namespace; |
| 38 | $this->lockKey = $this->namespace; |
| 39 | $this->defaultTtl = $defaultTtl ?: self::DEFAULT_TTL; |
| 40 | } |
| 41 | /** |
| 42 | * For BC only |
| 43 | * |
| 44 | * @todo remove in Matomo 6.0 |
| 45 | * @deprecated use {@link reacquireLock()} instead. |
| 46 | */ |
| 47 | public function reexpireLock() : bool |
| 48 | { |
| 49 | return $this->reacquireLock(); |
| 50 | } |
| 51 | /** |
| 52 | * Reacquires the current lock. The TTL will be extended if 1/4 of the TTL already passed by. |
| 53 | * |
| 54 | */ |
| 55 | public function reacquireLock() : bool |
| 56 | { |
| 57 | $timeBetweenReexpires = $this->defaultTtl - $this->defaultTtl / 4; |
| 58 | $now = Date::getNowTimestamp(); |
| 59 | if (!empty($this->lastAcquireTime) && $now <= $this->lastAcquireTime + $timeBetweenReexpires) { |
| 60 | return \false; |
| 61 | } |
| 62 | return $this->expireLock($this->defaultTtl); |
| 63 | } |
| 64 | public function getNumberOfAcquiredLocks() : int |
| 65 | { |
| 66 | return count($this->getAllAcquiredLockKeys()); |
| 67 | } |
| 68 | /** |
| 69 | * Returns all acquired lock keys for the iniatially set namespace. |
| 70 | * |
| 71 | * @return string[] |
| 72 | */ |
| 73 | public function getAllAcquiredLockKeys() : array |
| 74 | { |
| 75 | return $this->backend->getKeysMatchingPattern($this->namespace . '*'); |
| 76 | } |
| 77 | /** |
| 78 | * Executes and returns the result of the provided callback if a lock with given id can be acquired |
| 79 | * The method will automatically retry to acquire the lock up to 5 minutes. |
| 80 | * |
| 81 | * @param string $id |
| 82 | * @param callable $callback |
| 83 | * @return mixed |
| 84 | * @throws \Exception if lock couldn't be acquired within 5 minutes |
| 85 | */ |
| 86 | public function execute($id, $callback) |
| 87 | { |
| 88 | $i = 0; |
| 89 | while (!$this->acquireLock($id)) { |
| 90 | $i++; |
| 91 | usleep(100 * 1000); |
| 92 | // 100ms |
| 93 | if ($i > 50) { |
| 94 | // give up after 5seconds (50 * 100ms) |
| 95 | throw new \Exception('Could not get the lock for ID: ' . $id); |
| 96 | } |
| 97 | } |
| 98 | try { |
| 99 | return $callback(); |
| 100 | } finally { |
| 101 | $this->unlock(); |
| 102 | } |
| 103 | } |
| 104 | /** |
| 105 | * Acquires a lock with the given id using the provided TTL |
| 106 | * |
| 107 | * @param string $id |
| 108 | * @param int $ttlInSeconds |
| 109 | * @return bool |
| 110 | */ |
| 111 | public function acquireLock($id, $ttlInSeconds = 60) |
| 112 | { |
| 113 | $this->lockKey = $this->namespace . $id; |
| 114 | if (mb_strlen($this->lockKey) > self::MAX_KEY_LEN) { |
| 115 | // Lock key might be too long for DB column, so we hash it but leave the start of the original as well |
| 116 | // to make it more readable and to ensure the namespaceis still containe |
| 117 | $md5Len = 32; |
| 118 | $this->lockKey = mb_substr($this->lockKey, 0, self::MAX_KEY_LEN - $md5Len - 1) . md5($id); |
| 119 | } |
| 120 | $lockValue = substr(Common::generateUniqId(), 0, 12); |
| 121 | $locked = $this->backend->setIfNotExists($this->lockKey, $lockValue, $ttlInSeconds); |
| 122 | if ($locked) { |
| 123 | $this->lockValue = $lockValue; |
| 124 | $this->lastAcquireTime = Date::getNowTimestamp(); |
| 125 | } |
| 126 | return !!$locked; |
| 127 | } |
| 128 | /** |
| 129 | * Return if the acquired lock is currently locked |
| 130 | * |
| 131 | */ |
| 132 | public function isLocked() : bool |
| 133 | { |
| 134 | if (!$this->lockValue) { |
| 135 | return \false; |
| 136 | } |
| 137 | return $this->lockValue === $this->backend->get($this->lockKey); |
| 138 | } |
| 139 | /** |
| 140 | * Releases the acquired lock |
| 141 | * |
| 142 | */ |
| 143 | public function unlock() : void |
| 144 | { |
| 145 | if ($this->lockValue) { |
| 146 | $this->backend->deleteIfKeyHasValue($this->lockKey, $this->lockValue); |
| 147 | $this->lockValue = null; |
| 148 | } |
| 149 | } |
| 150 | /** |
| 151 | * For BC only |
| 152 | * |
| 153 | * @deprecated use {@link extendLock()} instead. |
| 154 | * @todo remove in Matomo 6.0 |
| 155 | */ |
| 156 | public function expireLock($ttlInSeconds) : bool |
| 157 | { |
| 158 | return $this->extendLock($ttlInSeconds); |
| 159 | } |
| 160 | public function extendLock($ttlInSeconds) : bool |
| 161 | { |
| 162 | if ($ttlInSeconds > 0) { |
| 163 | if ($this->lockValue) { |
| 164 | $success = $this->backend->expireIfKeyHasValue($this->lockKey, $this->lockValue, $ttlInSeconds); |
| 165 | if (!$success) { |
| 166 | $value = $this->backend->get($this->lockKey); |
| 167 | $message = sprintf('Failed to expire key %s (%s / %s).', $this->lockKey, $this->lockValue, (string) $value); |
| 168 | if ($value === \false) { |
| 169 | Common::printDebug($message . ' It seems like the key already expired as it no longer exists.'); |
| 170 | } elseif (!empty($value) && $value == $this->lockValue) { |
| 171 | Common::printDebug($message . ' We still have the lock but for some reason it did not expire.'); |
| 172 | } elseif (!empty($value)) { |
| 173 | Common::printDebug($message . ' This lock has been acquired by another process/server.'); |
| 174 | } else { |
| 175 | Common::printDebug($message . ' Failed to expire key.'); |
| 176 | } |
| 177 | return \false; |
| 178 | } |
| 179 | $this->lastAcquireTime = Date::getNowTimestamp(); |
| 180 | return \true; |
| 181 | } else { |
| 182 | Common::printDebug('Lock is not acquired, cannot update expiration.'); |
| 183 | } |
| 184 | } else { |
| 185 | Common::printDebug('Provided TTL ' . $ttlInSeconds . ' is in valid in Lock::expireLock().'); |
| 186 | } |
| 187 | return \false; |
| 188 | } |
| 189 | } |
| 190 |