From 597e6c66d54af0596cfe218073a9a5002dea4213 Mon Sep 17 00:00:00 2001
From: John Eskew <jeskew@edx.org>
Date: Tue, 22 May 2018 15:28:11 -0400
Subject: [PATCH] Add backoff module as a new requirement. Use backoff when
 calling Sailthru API to retry upon optout timeouts.

---
 lms/djangoapps/email_marketing/signals.py | 17 +++++++++++++++++
 requirements/edx/base.in                  |  1 +
 requirements/edx/base.txt                 |  1 +
 requirements/edx/development.txt          |  1 +
 requirements/edx/testing.txt              |  1 +
 5 files changed, 21 insertions(+)

diff --git a/lms/djangoapps/email_marketing/signals.py b/lms/djangoapps/email_marketing/signals.py
index 13cecaf21b..90a6d6561b 100644
--- a/lms/djangoapps/email_marketing/signals.py
+++ b/lms/djangoapps/email_marketing/signals.py
@@ -5,6 +5,7 @@ import datetime
 import logging
 from random import randint
 
+import backoff
 import crum
 from celery.exceptions import TimeoutError
 from django.conf import settings
@@ -263,7 +264,23 @@ def _log_sailthru_api_call_time(time_before_call):
              delta_sailthru_api_call_time.microseconds / 1000)
 
 
+def _backoff_handler(details):
+    """
+    Simple logging handler for when timeout backoff occurs.
+    """
+    log.info('Trying again in {wait:0.1f} seconds after {tries} tries calling {target}'.format(**details))
+
+
+def _not_a_timeout(e):
+    return 'timed out' not in e.message
+
+
 @receiver(USER_RETIRE_MAILINGS)
+@backoff.on_exception(backoff.expo,
+                      Exception,
+                      max_time=600,  # Only 10 minutes of trying
+                      giveup=_not_a_timeout,  # Stop trying if exception is *not* a timeout.
+                      on_backoff=_backoff_handler)
 def force_unsubscribe_all(sender, **kwargs):  # pylint: disable=unused-argument
     """
     Synchronously(!) unsubscribes the given user from all Sailthru email lists.
diff --git a/requirements/edx/base.in b/requirements/edx/base.in
index 27ed86bf2d..1512ec0b13 100644
--- a/requirements/edx/base.in
+++ b/requirements/edx/base.in
@@ -26,6 +26,7 @@
 analytics-python==1.1.0             # Used for Segment analytics
 attrs                               # Reduces boilerplate code involving class attributes
 Babel==1.3                          # Internationalization utilities, used for date formatting in a few places
+backoff
 bleach==1.4                         # Allowed-list-based HTML sanitizing library that escapes or strips markup and attributes; used for capa and LTI
 boto==2.39.0                        # Deprecated version of the AWS SDK; we should stop using this
 boto3==1.4.8                        # Amazon Web Services SDK for Python
diff --git a/requirements/edx/base.txt b/requirements/edx/base.txt
index a41ad6d631..556965fbee 100644
--- a/requirements/edx/base.txt
+++ b/requirements/edx/base.txt
@@ -51,6 +51,7 @@ argparse==1.4.0
 asn1crypto==0.24.0
 attrs==17.4.0
 babel==1.3
+backoff==1.5.0
 beautifulsoup==3.2.1      # via pynliner
 billiard==3.3.0.23        # via celery
 bleach==1.4
diff --git a/requirements/edx/development.txt b/requirements/edx/development.txt
index b82870b7e1..7c831e0a32 100644
--- a/requirements/edx/development.txt
+++ b/requirements/edx/development.txt
@@ -57,6 +57,7 @@ asn1crypto==0.24.0
 astroid==1.5.2
 attrs==17.4.0
 babel==1.3
+backoff==1.5.0
 backports.functools-lru-cache==1.5
 beautifulsoup4==4.6.0
 beautifulsoup==3.2.1
diff --git a/requirements/edx/testing.txt b/requirements/edx/testing.txt
index 065b637032..5a35a8878e 100644
--- a/requirements/edx/testing.txt
+++ b/requirements/edx/testing.txt
@@ -54,6 +54,7 @@ asn1crypto==0.24.0
 astroid==1.5.2            # via edx-lint, pylint, pylint-celery, pylint-plugin-utils
 attrs==17.4.0
 babel==1.3
+backoff==1.5.0
 backports.functools-lru-cache==1.5  # via astroid, pylint
 beautifulsoup4==4.6.0
 beautifulsoup==3.2.1