tree 750103032e4860ab2be3f540eb5993f45e133365
parent 1306455ce5eb75c74790526ec3687293221a42ba
author mdooley <mdooley@google.com> 1511927692 -0800
committer Copybara-Service <copybara-piper@google.com> 1511984997 -0800

Switching to alarms and exponential backoff while polling for transcription result

This cl switches the way asynchronous transcription tasks poll for their
results.  it has been observed that sometimes the server side transcription
takes longer than expected (sometimes many minutes), so instead of blocking
a thread for all that time this cl schedules an alarm for the next time to
poll.  it also uses an exponential backoff scheme to determine the poll times
and increases the maximum total polling time from 20 seconds to 20 minutes.

Bug: 66966157
Test: manual and unit tests
PiperOrigin-RevId: 177257577
Change-Id: Ib2998f03cc418d5241ccffec71ba3945c9fe4cbc