75 lines
2.1 KiB
PHP
75 lines
2.1 KiB
PHP
<?php
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namespace Aws;
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/**
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* Simple in-memory LRU cache that limits the number of cached entries.
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*
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* The LRU cache is implemented using PHP's ordered associative array. When
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* accessing an element, the element is removed from the hash and re-added to
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* ensure that recently used items are always at the end of the list while
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* least recently used are at the beginning. When a value is added to the
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* cache, if the number of cached items exceeds the allowed number, the first
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* N number of items are removed from the array.
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*/
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class LruArrayCache implements CacheInterface
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{
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/** @var int */
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private $maxItems;
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/** @var array */
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private $items;
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/**
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* @param int $maxItems Maximum number of allowed cache items.
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*/
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public function __construct($maxItems = 1000)
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{
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$this->maxItems = $maxItems;
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}
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public function get($key)
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{
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if (!isset($this->items[$key])) {
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return null;
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}
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$entry = $this->items[$key];
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// Ensure the item is not expired.
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if (!$entry[1] || time() < $entry[1]) {
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// LRU: remove the item and push it to the end of the array.
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unset($this->items[$key]);
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$this->items[$key] = $entry;
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return $entry[0];
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}
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unset($this->items[$key]);
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return null;
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}
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public function set($key, $value, $ttl = 0)
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{
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// Only call time() if the TTL is not 0/false/null
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$ttl = $ttl ? time() + $ttl : 0;
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$this->items[$key] = [$value, $ttl];
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// Determine if there are more items in the cache than allowed.
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$diff = count($this->items) - $this->maxItems;
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// Clear out least recently used items.
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if ($diff > 0) {
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// Reset to the beginning of the array and begin unsetting.
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reset($this->items);
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for ($i = 0; $i < $diff; $i++) {
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unset($this->items[key($this->items)]);
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next($this->items);
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}
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}
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}
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public function remove($key)
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{
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unset($this->items[$key]);
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}
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}
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