MongoCollection::getIndexInfo PHP Method

    public function getIndexInfo()
    {
        $convertIndex = function (\MongoDB\Model\IndexInfo $indexInfo) {
            return ['v' => $indexInfo->getVersion(), 'key' => $indexInfo->getKey(), 'name' => $indexInfo->getName(), 'ns' => $indexInfo->getNamespace()];
        };
        return array_map($convertIndex, iterator_to_array($this->collection->listIndexes()));
    }

 /**
  * Ensure index of correct specification and a unique name whether the specification or name already exist or not.
  * Will not create index if $index is a prefix of an existing index
  *
  * @param array $index index to create in same format as \MongoCollection::ensureIndex()
  *
  * @return void
  *
  * @throws \Exception couldnt create index after 5 attempts
  */
 private function _ensureIndex(array $index)
 {
     //if $index is a prefix of any existing index we are good
     foreach ($this->_collection->getIndexInfo() as $existingIndex) {
         $slice = array_slice($existingIndex['key'], 0, count($index), true);
         if ($slice === $index) {
             return;
         }
     }
     for ($i = 0; $i < 5; ++$i) {
         for ($name = uniqid(); strlen($name) > 0; $name = substr($name, 0, -1)) {
             //creating an index with same name and different spec does nothing.
             //creating an index with same spec and different name does nothing.
             //so we use any generated name, and then find the right spec after we have called, and just go with that name.
             try {
                 $this->_collection->ensureIndex($index, array('name' => $name, 'background' => true));
             } catch (\MongoException $e) {
                 //this happens when the name was too long, let continue
             }
             foreach ($this->_collection->getIndexInfo() as $existingIndex) {
                 if ($existingIndex['key'] === $index) {
                     return;
                 }
             }
         }
     }
     throw new \Exception('couldnt create index after 5 attempts');
 }