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<?php |
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namespace MatthiasMullie\Scrapbook\Psr6; |
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use MatthiasMullie\Scrapbook\KeyValueStore; |
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/** |
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* Helper object to serve as glue between pool & item. |
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* |
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* New items are created by first get()-ing them from the pool. It would be |
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* inefficient to let such a get() immediately query the real cache (because it |
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* may not be meant to retrieve real data, but just to set a new value) |
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* |
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* Instead, every Item returned by get() will be a "placeholder", and once the |
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* values are actually needed, this object will be called to go do that (along |
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* with every other value that has not yet been resolved, while we're at it) |
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* |
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* @author Matthias Mullie <[email protected]> |
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* @copyright Copyright (c) 2014, Matthias Mullie. All rights reserved |
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* @license LICENSE MIT |
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*/ |
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class Repository |
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{ |
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/** |
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* @var KeyValueStore |
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*/ |
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protected $store; |
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/** |
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* Array of resolved items. |
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* |
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* @var mixed[] [unique => value] |
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*/ |
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protected $resolved = array(); |
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/** |
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* Array of unresolved items. |
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* |
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* @var string[] [unique => key] |
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*/ |
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protected $unresolved = array(); |
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public function __construct(KeyValueStore $store) |
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{ |
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$this->store = $store; |
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} |
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/** |
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* Add a to-be-resolved cache key. |
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* |
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* @param string $unique |
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* @param string $key |
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*/ |
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public function add($unique, $key) |
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{ |
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$this->unresolved[$unique] = $key; |
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} |
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/** |
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* This repository holds the real values for all Item objects. However, if |
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* such an item gets garbage collected, there is no point in wasting any |
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* more memory storing that value. |
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* In that case, this method can be called to remove those values. |
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* |
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* @param string $unique |
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*/ |
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public function remove($unique) |
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{ |
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unset($this->unresolved[$unique], $this->resolved[$unique]); |
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} |
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/** |
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* @param string $unique |
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* |
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* @return mixed|null Value, of null if non-existent |
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*/ |
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public function get($unique) |
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{ |
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return $this->exists($unique) ? $this->resolved[$unique] : null; |
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} |
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/** |
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* @param string $unique |
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* |
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* @return bool |
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*/ |
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public function exists($unique) |
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{ |
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if (array_key_exists($unique, $this->unresolved)) { |
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$this->resolve(); |
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} |
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return array_key_exists($unique, $this->resolved); |
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} |
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/** |
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* Resolve all unresolved keys at once. |
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*/ |
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protected function resolve() |
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{ |
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$keys = array_unique(array_values($this->unresolved)); |
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$values = $this->store->getMulti($keys); |
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foreach ($this->unresolved as $unique => $key) { |
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if (!array_key_exists($key, $values)) { |
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// key doesn't exist in cache |
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continue; |
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} |
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/* |
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* In theory, there could've been multiple unresolved requests for |
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* the same cache key. In the case of objects, we'll clone them |
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* to make sure that when the value for 1 item is manipulated, it |
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* doesn't affect the value of the other item (because those objects |
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* would be passed by-ref without the cloning) |
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*/ |
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$value = $values[$key]; |
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$value = is_object($value) ? clone $value : $value; |
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$this->resolved[$unique] = $value; |
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} |
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$this->unresolved = array(); |
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} |
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} |
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