From 7d175c0c6bd607801c6a6d78679eb3e0feedb0ec Mon Sep 17 00:00:00 2001
From: slawekrewaj <slawek@rewsoft.pl>
Date: Wed, 18 Sep 2019 13:44:47 +0200
Subject: [PATCH] Adding retries on errors with exponenential backoff

---
 tap_exacttarget/__init__.py |  8 +++-
 tap_exacttarget/client.py   | 87 +++++++++++++++++++++++++++++++------
 2 files changed, 80 insertions(+), 15 deletions(-)

diff --git a/tap_exacttarget/__init__.py b/tap_exacttarget/__init__.py
index 66c61a0..16ae22c 100644
--- a/tap_exacttarget/__init__.py
+++ b/tap_exacttarget/__init__.py
@@ -9,7 +9,9 @@
 
 from tap_exacttarget.state import save_state
 
-from tap_exacttarget.client import get_auth_stub
+from tap_exacttarget.client import get_auth_stub, change_retry_count
+from tap_exacttarget.client import change_min_retry_delay_seconds
+from tap_exacttarget.client import change_max_retry_delay_seconds
 
 from tap_exacttarget.endpoints.campaigns \
     import CampaignDataAccessObject
@@ -88,6 +90,10 @@ def do_sync(args):
 
     auth_stub = get_auth_stub(config)
 
+    change_retry_count(config.get('retry_count', 5))
+    change_min_retry_delay_seconds(config.get('min_retry_delay_seconds', 5))
+    change_max_retry_delay_seconds(config.get('max_retry_delay_seconds', 600))
+
     stream_accessors = []
 
     subscriber_selected = False
diff --git a/tap_exacttarget/client.py b/tap_exacttarget/client.py
index 08e40a3..2cbabc9 100644
--- a/tap_exacttarget/client.py
+++ b/tap_exacttarget/client.py
@@ -1,3 +1,6 @@
+import time
+import traceback
+
 import FuelSDK
 import singer
 
@@ -17,10 +20,75 @@ def _get_response_items(response):
     return items
 
 
-__all__ = ['get_auth_stub', 'request', 'request_from_cursor']
+class RetryDecorator(object):
+    retry_count = 1
+    min_retry_delay_seconds = 5
+    max_retry_delay_seconds = 600
+
+    def __init__(self, func):
+        self.func = func
+
+    def __call__(self, *args, **kwargs):
+        retry_number = 0
+
+        while retry_number < self.retry_count:
+            try:
+                return self.func(*args, **kwargs)
+            except Exception as e:
+                LOGGER.error(
+                    u"Error reading data from API on try {}".format(
+                        retry_number + 1))
+                LOGGER.error(traceback.format_exc())
+
+                retry_number += 1
+                retry_delay = min(
+                    self.min_retry_delay_seconds * retry_number * retry_number,
+                    self.max_retry_delay_seconds)
+                time.sleep(retry_delay)
+                continue
+
+        raise RuntimeError("Maximum number of retries reached")
+
+
+@RetryDecorator
+def _get_data_from_cursor(cursor):
+    response = cursor.get()
+    if not response.status:
+        raise RuntimeError("Request failed with '{}'"
+                           .format(response.message))
+    return response
+
+
+@RetryDecorator
+def _get_more_results(cursor, batch_size):
+    response = tap_exacttarget__getMoreResults(
+        cursor, batch_size=batch_size)
+    if not response.status:
+        raise RuntimeError("Request failed with '{}'"
+                           .format(response.message))
+    return response
+
+
+__all__ = ['change_retry_count',
+           'change_min_retry_delay_seconds',
+           'change_max_retry_delay_seconds',
+           'get_auth_stub',
+           'request',
+           'request_from_cursor']
 
 
 # PUBLIC FUNCTIONS
+def change_retry_count(new_retry_count):
+    RetryDecorator.retry_count = new_retry_count
+
+
+def change_min_retry_delay_seconds(new_min_retry_delay_seconds):
+    RetryDecorator.min_retry_delay_seconds = new_min_retry_delay_seconds
+
+
+def change_max_retry_delay_seconds(new_max_retry_delay_seconds):
+    RetryDecorator.max_retry_delay_seconds = new_max_retry_delay_seconds
+
 
 def get_auth_stub(config):
     """
@@ -108,26 +176,17 @@ def request_from_cursor(name, cursor, batch_size):
     to be customized. See tap_exacttarget.endpoints.data_extensions for
     an example.
     """
-    response = cursor.get()
-
-    if not response.status:
-        raise RuntimeError("Request failed with '{}'"
-                           .format(response.message))
-
+    response = _get_data_from_cursor(cursor)
     for item in _get_response_items(response):
         yield item
 
     while response.more_results:
         LOGGER.info("Getting more results from '{}' endpoint".format(name))
 
-        # Override call to getMoreResults to add a batch_size parameter
-        # response = cursor.getMoreResults()
-        response = tap_exacttarget__getMoreResults(cursor, batch_size=batch_size)
-        LOGGER.info("Fetched {} results from '{}' endpoint".format(len(response.results), name))
+        response = _get_more_results(cursor, batch_size)
 
-        if not response.status:
-            raise RuntimeError("Request failed with '{}'"
-                               .format(response.message))
+        LOGGER.info("Fetched {} results from '{}' endpoint".format(
+            len(response.results), name))
 
         for item in _get_response_items(response):
             yield item