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File: application/modules/extensions/aws/Aws/LruArrayCache.php

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File: application/modules/extensions/aws/Aws/LruArrayCache.php
Role: Application script
Content type: text/plain
Description: Initial
Class: Pretty PHP S3 Files Manager
Web based interface to manage files in Amazon S3
Author: By
Last change:
Date: 3 years ago
Size: 2,109 bytes
 

 

Contents

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<?php
namespace Aws;

/**
 * Simple in-memory LRU cache that limits the number of cached entries.
 *
 * The LRU cache is implemented using PHP's ordered associative array. When
 * accessing an element, the element is removed from the hash and re-added to
 * ensure that recently used items are always at the end of the list while
 * least recently used are at the beginning. When a value is added to the
 * cache, if the number of cached items exceeds the allowed number, the first
 * N number of items are removed from the array.
 */
class LruArrayCache implements CacheInterface
{
   
/** @var int */
   
private $maxItems;

   
/** @var array */
   
private $items;

   
/**
     * @param int $maxItems Maximum number of allowed cache items.
     */
   
public function __construct($maxItems = 1000)
    {
       
$this->maxItems = $maxItems;
    }

    public function
get($key)
    {
        if (!isset(
$this->items[$key])) {
            return
null;
        }

       
$entry = $this->items[$key];

       
// Ensure the item is not expired.
       
if (!$entry[1] || time() < $entry[1]) {
           
// LRU: remove the item and push it to the end of the array.
           
unset($this->items[$key]);
           
$this->items[$key] = $entry;
            return
$entry[0];
        }

        unset(
$this->items[$key]);
        return
null;
    }

    public function
set($key, $value, $ttl = 0)
    {
       
// Only call time() if the TTL is not 0/false/null
       
$ttl = $ttl ? time() + $ttl : 0;
       
$this->items[$key] = [$value, $ttl];

       
// Determine if there are more items in the cache than allowed.
       
$diff = count($this->items) - $this->maxItems;

       
// Clear out least recently used items.
       
if ($diff > 0) {
           
// Reset to the beginning of the array and begin unsetting.
           
reset($this->items);
            for (
$i = 0; $i < $diff; $i++) {
                unset(
$this->items[key($this->items)]);
               
next($this->items);
            }
        }
    }

    public function
remove($key)
    {
        unset(
$this->items[$key]);
    }
}