S3Cache.php

<?php 

namespace common\components;


use Aws\S3\S3Client;
use yii\caching\Cache;
use yii\helpers\ArrayHelper;

class S3Cache extends Cache {
    public $bucket;

    public function __construct(S3Client $client, $config = []) {
        $this->keyPrefix = '';
        $this->_client = $client;
        parent::__construct($config);
    }

    /**
     * @var S3Client
     */
    private $_client;

    /**
     * @return S3Client
     */
    public function getClient() {
        return $this->_client;
    }


    /**
     * Retrieves a value from cache with a specified key.
     * This method should be implemented by child classes to retrieve the data
     * from specific cache storage.
     * @param string $key a unique key identifying the cached value
     * @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
     */
    protected function getValue($key) {
        $time = time();
        if ($this->getClient()->doesObjectExist($this->bucket, $this->buildKey($key))) {
            $result = $this->getClient()->getObject([
                'Bucket' => $this->bucket,
                'Key' => $this->buildKey($key)
            ]);
            $entry = unserialize($result['Body']);
            $expiration = ArrayHelper::getValue($entry, 'expiration');
            if (!$expiration || $expiration > $time) {
                return ArrayHelper::getValue($entry, 'value');
            }
        }
        return false;
    }

    /**
     * Stores a value identified by a key in cache.
     * This method should be implemented by child classes to store the data
     * in specific cache storage.
     * @param string $key the key identifying the value to be cached
     * @param string $value the value to be cached
     * @param integer $duration the number of seconds in which the cached value will expire. 0 means never expire.
     * @return boolean true if the value is successfully stored into cache, false otherwise
     */
    protected function setValue($key, $value, $duration) {
        $entry = array_filter([
            'value' => $value,
            'expiration' => $duration ? time() + $duration : null
        ]);
        return $this->getClient()->putObject([
            'Bucket' => $this->bucket,
            'Key' => $this->buildKey($key),
            'Body' => serialize($entry)
        ]) !== null;
    }

    /**
     * Stores a value identified by a key into cache if the cache does not contain this key.
     * This method should be implemented by child classes to store the data
     * in specific cache storage.
     * @param string $key the key identifying the value to be cached
     * @param string $value the value to be cached
     * @param integer $duration the number of seconds in which the cached value will expire. 0 means never expire.
     * @return boolean true if the value is successfully stored into cache, false otherwise
     */
    protected function addValue($key, $value, $duration) {
        if (!$this->getClient()->doesObjectExist($this->bucket, $this->buildKey($key))) {
            return $this->setValue($key, $value, $duration);
        }
        return false;
    }

    /**
     * Deletes a value with the specified key from cache
     * This method should be implemented by child classes to delete the data from actual cache storage.
     * @param string $key the key of the value to be deleted
     * @return boolean if no error happens during deletion
     */
    protected function deleteValue($key) {
        $this->getClient()->deleteMatchingObjects($this->bucket, $this->keyPrefix, "/" . $this->buildKey($key) . "/");
        return true;
    }

    /**
     * Deletes all values from cache.
     * Child classes may implement this method to realize the flush operation.
     * @return boolean whether the flush operation was successful.
     */
    protected function flushValues() {
        $this->getClient()->deleteMatchingObjects($this->bucket, $this->keyPrefix, "/.*/");
    }
}