How to catch task failure on Google App Engine?

Question

Google App Engine provides us with task queues (task queue reference). I use a push queue configured to retry failed tasks 4 times. I would like to handle a case when task fails completely, all 4 tries haven't succeed.

Is there is a way to handle full task failure with taskqueue API? Kind of post mortem handler.

   <queue>
    <name>my-queue</name>
    <rate>100/s</rate>
    <bucket-size>100</bucket-size>
    <retry-parameters>
        <task-retry-limit>4</task-retry-limit>
        <min-backoff-seconds>10</min-backoff-seconds>
        <max-backoff-seconds>200</max-backoff-seconds>
    </retry-parameters>
</queue>

Answer 1

Question is answered on GAE Forum.

Alejandro Gonzalez proposed to read number of tries from special GAE header and handle everything else on one's own.

String retryCount = request.getHeader("X-AppEngine-TaskRetryCount");