From 41a782e01105150ae49c742e0c36d56c8830ef67 Mon Sep 17 00:00:00 2001
From: Zev Benjamin <zev@zulip.com>
Date: Tue, 11 Mar 2014 14:09:15 -0400
Subject: [PATCH] Move backoff classes to the Zulip API

(imported from commit 76c5d499874f0397c505ab3fcda631a1a46847b6)
---
 bots/zephyr_mirror.py         |  4 +++-
 bots/zephyr_mirror_backend.py | 37 +++--------------------------------
 zulip/__init__.py             | 31 +++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 35 deletions(-)

diff --git a/bots/zephyr_mirror.py b/bots/zephyr_mirror.py
index a976131..a3375ca 100755
--- a/bots/zephyr_mirror.py
+++ b/bots/zephyr_mirror.py
@@ -28,7 +28,6 @@ import traceback
 import signal
 
 from zephyr_mirror_backend import parse_args
-from zephyr_mirror_backend import RandomExponentialBackoff
 
 def die(signal, frame):
     # We actually want to exit, so run os._exit (so as not to be caught and restarted)
@@ -38,6 +37,9 @@ signal.signal(signal.SIGINT, die)
 
 (options, args) = parse_args()
 
+sys.path[:0] = [os.path.join(options.root_path, 'api')]
+from zulip import RandomExponentialBackoff
+
 args = [os.path.join(options.root_path, "user_root", "zephyr_mirror_backend.py")]
 args.extend(sys.argv[1:])
 
diff --git a/bots/zephyr_mirror_backend.py b/bots/zephyr_mirror_backend.py
index 9b92b3a..9d9a4bd 100755
--- a/bots/zephyr_mirror_backend.py
+++ b/bots/zephyr_mirror_backend.py
@@ -37,39 +37,8 @@ import signal
 import logging
 import hashlib
 import tempfile
-import random
 import select
 
-class CountingBackoff(object):
-    def __init__(self, maximum_retries=10):
-        self.number_of_retries = 0
-        self.maximum_retries = maximum_retries
-
-    def keep_going(self):
-        return self.number_of_retries < self.maximum_retries
-
-    def succeed(self):
-        self.number_of_retries = 0
-
-    def fail(self):
-        self.number_of_retries = min(self.number_of_retries + 1,
-                                     self.maximum_retries)
-
-class RandomExponentialBackoff(CountingBackoff):
-    def fail(self):
-        self.number_of_retries = min(self.number_of_retries + 1,
-                                     self.maximum_retries)
-        # Exponential growth with ratio sqrt(2); compute random delay
-        # between x and 2x where x is growing exponentially
-        delay_scale = int(2 ** (self.number_of_retries / 2.0 - 1)) + 1
-        delay = delay_scale + random.randint(1, delay_scale)
-        message = "Sleeping for %ss [max %s] before retrying." % (delay, delay_scale * 2)
-        try:
-            logger.warning(message)
-        except NameError:
-            print message
-        time.sleep(delay)
-
 DEFAULT_SITE = "https://api.zulip.com"
 
 class States:
@@ -478,7 +447,7 @@ def quit_failed_initialization(message):
     sys.exit(1)
 
 def zephyr_init_autoretry():
-    backoff = RandomExponentialBackoff()
+    backoff = zulip.RandomExponentialBackoff()
     while backoff.keep_going():
         try:
             # zephyr.init() tries to clear old subscriptions, and thus
@@ -493,7 +462,7 @@ def zephyr_init_autoretry():
     quit_failed_initialization("Could not initialize Zephyr library, quitting!")
 
 def zephyr_load_session_autoretry(session_path):
-    backoff = RandomExponentialBackoff()
+    backoff = zulip.RandomExponentialBackoff()
     while backoff.keep_going():
         try:
             session = file(session_path, "r").read()
@@ -508,7 +477,7 @@ def zephyr_load_session_autoretry(session_path):
     quit_failed_initialization("Could not load saved Zephyr session, quitting!")
 
 def zephyr_subscribe_autoretry(sub):
-    backoff = RandomExponentialBackoff()
+    backoff = zulip.RandomExponentialBackoff()
     while backoff.keep_going():
         try:
             zephyr.Subscriptions().add(sub)
diff --git a/zulip/__init__.py b/zulip/__init__.py
index ce71ef3..92f8b5b 100644
--- a/zulip/__init__.py
+++ b/zulip/__init__.py
@@ -30,6 +30,7 @@ import os
 import optparse
 import platform
 import urllib
+import random
 from distutils.version import LooseVersion
 
 from ConfigParser import SafeConfigParser
@@ -46,6 +47,36 @@ requests_json_is_function = callable(requests.Response.json)
 
 API_VERSTRING = "v1/"
 
+class CountingBackoff(object):
+    def __init__(self, maximum_retries=10):
+        self.number_of_retries = 0
+        self.maximum_retries = maximum_retries
+
+    def keep_going(self):
+        return self.number_of_retries < self.maximum_retries
+
+    def succeed(self):
+        self.number_of_retries = 0
+
+    def fail(self):
+        self.number_of_retries = min(self.number_of_retries + 1,
+                                     self.maximum_retries)
+
+class RandomExponentialBackoff(CountingBackoff):
+    def fail(self):
+        self.number_of_retries = min(self.number_of_retries + 1,
+                                     self.maximum_retries)
+        # Exponential growth with ratio sqrt(2); compute random delay
+        # between x and 2x where x is growing exponentially
+        delay_scale = int(2 ** (self.number_of_retries / 2.0 - 1)) + 1
+        delay = delay_scale + random.randint(1, delay_scale)
+        message = "Sleeping for %ss [max %s] before retrying." % (delay, delay_scale * 2)
+        try:
+            logger.warning(message)
+        except NameError:
+            print message
+        time.sleep(delay)
+
 def _default_client():
     return "ZulipPython/" + __version__