如何知道Amazon DynamoDB何时完成BatchRequest？

I've created tool that imports about 50-250 thousands rows to the database, the problem is that I don't know when it's been completed.

I'm using WriteRequestBatch from the PHP SDK: http://docs.aws.amazon.com/aws-sdk-php/guide/latest/service-dynamodb.html#using-the-writerequestbatch

Is there any way to know when It's done?