Aws\S3\S3MultiRegionClient::determineBucketRegionAsync PHP Method

    public function determineBucketRegionAsync($bucketName)
    {
        if ($cached = $this->cache->get($this->getCacheKey($bucketName))) {
            return Promise\promise_for($cached);
        }
        return $this->lookupBucketRegion($bucketName)->then(function ($region) use($bucketName) {
            $this->cache->set($this->getCacheKey($bucketName), $region);
            return $region;
        });
    }