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April 8, 2016 14:40
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| <?php | |
| namespace Maxwell\Cache; | |
| /** | |
| * Class PhpLruCache | |
| * | |
| * Inner node has following structure (it is stdClass) | |
| * until -> expiration time or null | |
| * key -> key | |
| * value -> value itself | |
| * prev -> previous node (reference) | |
| * next -> next node (reference) | |
| * | |
| * @package Maxwell\Cache | |
| */ | |
| class PhpLruCache implements CacheInterface, \Countable | |
| { | |
| private $capacity; | |
| private $ttl; | |
| private $map = []; | |
| private $oldest = null; | |
| private $newest = null; | |
| /** | |
| * PhpLruCache constructor. | |
| * | |
| * @param int $capacity Expected maximum capacity | |
| * @param int $ttl Time to live in seconds, zero or negative value for infinity | |
| */ | |
| public function __construct($capacity, $ttl) | |
| { | |
| if (!is_int($capacity) || $capacity < 1) { | |
| throw new \InvalidArgumentException('$capacity should be int and greater, than 0'); | |
| } | |
| if (!is_int($ttl)) { | |
| throw new \InvalidArgumentException('$ttl must be integer'); | |
| } | |
| $this->capacity = $capacity; | |
| $this->ttl = $ttl; | |
| } | |
| /** | |
| * Returns cache with requested parameters | |
| * | |
| * @param string $prefix | |
| * @param int $ttl Time in seconds | |
| * @return CacheInterface | |
| */ | |
| public function getCache($prefix, $ttl) | |
| { | |
| return new self($this->capacity, $ttl); | |
| } | |
| /** | |
| * @inheritdoc | |
| */ | |
| public function offsetExists($offset) | |
| { | |
| if (!array_key_exists($offset, $this->map)) { | |
| return false; | |
| } | |
| if ($this->ttl > 0 && $this->map[$offset]->until < time()) { | |
| // Value expired | |
| $this->offsetUnset($offset); | |
| return false; | |
| } | |
| return true; | |
| } | |
| /** | |
| * @inheritdoc | |
| */ | |
| public function offsetGet($offset) | |
| { | |
| if (!$this->offsetExists($offset)) { | |
| return null; | |
| } | |
| $node = $this->map[$offset]; | |
| if ($node !== $this->newest) { | |
| $this->placeNewestNode($node); | |
| } | |
| return $node->value; | |
| } | |
| /** | |
| * @inheritdoc | |
| */ | |
| public function offsetSet($offset, $value) | |
| { | |
| // Removing old node, if it presents | |
| $this->offsetUnset($offset); | |
| // Building node | |
| $node = new \stdClass(); | |
| $node->until = time() + $this->ttl; | |
| $node->key = $offset; | |
| $node->value = $value; | |
| $node->next = null; | |
| $node->prev = null; | |
| // Storing into map | |
| $this->map[$offset] = $node; | |
| // Adding to linked list | |
| $this->placeNewestNode($node); | |
| // Checking capacity | |
| if ($this->count() === $this->capacity + 1) { | |
| unset($this->map[$this->oldest->key]); | |
| $this->dropOldest(); | |
| } | |
| } | |
| /** | |
| * @inheritdoc | |
| */ | |
| public function offsetUnset($offset) | |
| { | |
| if (!isset($this->map[$offset])) { | |
| // Noting to delete | |
| return; | |
| } | |
| $node = $this->map[$offset]; | |
| unset($this->map[$offset]); | |
| $this->cutNode($node); | |
| } | |
| /** | |
| * @inheritdoc | |
| */ | |
| public function count() | |
| { | |
| return count($this->map); | |
| } | |
| /** | |
| * This method drops most oldest entry (MAP not changed) | |
| */ | |
| private function dropOldest() | |
| { | |
| if ($this->oldest !== null) { | |
| if ($this->oldest->next === null) { | |
| $this->oldest = null; | |
| $this->newest = null; | |
| } else { | |
| $this->oldest->next->prev = null; | |
| $this->oldest = $this->oldest->next; | |
| } | |
| } | |
| } | |
| /** | |
| * This method places provided node to the beginning of the linked list | |
| * | |
| * @param \stdClass $node | |
| */ | |
| private function placeNewestNode(\stdClass $node) | |
| { | |
| $this->cutNode($node); | |
| if ($this->oldest === null) { | |
| // Easy-peasy | |
| $this->oldest = $node; | |
| $this->newest = $node; | |
| } else { | |
| // Cross-linking | |
| $this->newest->next = $node; | |
| $node->prev = $this->newest; | |
| $this->newest = $node; | |
| } | |
| } | |
| /** | |
| * This methods cuts provided node from linked list | |
| * | |
| * @param \stdClass $node | |
| */ | |
| private function cutNode(\stdClass $node) | |
| { | |
| if ($node->next !== null) { | |
| $node->next->prev = $node->prev; | |
| } | |
| if ($node->prev !== null) { | |
| $node->prev->next = $node->next; | |
| } | |
| if ($this->oldest === $node) { | |
| $this->oldest = $node->next; | |
| } | |
| if ($this->newest === $node) { | |
| $this->newest = $node->prev; | |
| } | |
| $node->next = null; | |
| $node->prev = null; | |
| } | |
| /** | |
| * Removes all entries from cache | |
| */ | |
| public function flush() | |
| { | |
| $this->map = []; | |
| $this->newest = null; | |
| $this->oldest = null; | |
| } | |
| } |
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