1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
## Copyright 2013 Ray Holder
##
## Licensed under the Apache License, Version 2.0 (the "License");
## you may not use this file except in compliance with the License.
## You may obtain a copy of the License at
##
## http://www.apache.org/licenses/LICENSE-2.0
##
## Unless required by applicable law or agreed to in writing, software
## distributed under the License is distributed on an "AS IS" BASIS,
## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
## limitations under the License.
import random
import sys
import time
def retry(stop='never_stop', stop_max_attempt_number=5, stop_max_delay=100,
wait='no_sleep',
wait_fixed=1000,
wait_random_min=0, wait_random_max=1000,
wait_incrementing_start=0, wait_incrementing_increment=100,
wait_exponential_multiplier=100, wait_exponential_max=5000,
retry_on_exception=None, #TODO on_exception
retry_on_result=None): #TODO on_result
def wrap(f):
def wrapped_f(*args, **kw):
return Retrying(
stop=stop,
stop_max_attempt_number=stop_max_attempt_number,
stop_max_delay=stop_max_delay,
wait=wait,
wait_fixed=wait_fixed,
wait_random_min=wait_random_min,
wait_random_max=wait_random_max,
wait_incrementing_start=wait_incrementing_start,
wait_incrementing_increment=wait_incrementing_increment,
wait_exponential_multiplier=wait_exponential_multiplier,
wait_exponential_max=wait_exponential_max,
retry_on_exception=retry_on_exception,
retry_on_result=retry_on_result
).call(f, *args, **kw)
return wrapped_f
return wrap
class Retrying:
def __init__(self,
stop='never_stop', stop_max_attempt_number=5, stop_max_delay=100,
wait='no_sleep',
wait_fixed=1000,
wait_random_min=0, wait_random_max=1000,
wait_incrementing_start=0, wait_incrementing_increment=100,
wait_exponential_multiplier=1, wait_exponential_max=sys.maxint,
retry_on_exception=None, #TODO on_exception
retry_on_result=None): #TODO on_result
# stop behavior
self.stop = getattr(self, stop)
self._stop_max_attempt_number = stop_max_attempt_number
self._stop_max_delay = stop_max_delay
# control wait behavior
self.wait = getattr(self, wait)
self._wait_fixed = wait_fixed
self._wait_random_min = wait_random_min
self._wait_random_max = wait_random_max
self._wait_incrementing_start = wait_incrementing_start
self._wait_incrementing_increment = wait_incrementing_increment
self._wait_exponential_multiplier = wait_exponential_multiplier
self._wait_exponential_max = wait_exponential_max
# control retry on exception filter
if retry_on_exception is None:
self._retry_on_exception = self.never_reject
else:
self._retry_on_exception = retry_on_exception
# control retry on result filter
if retry_on_result is None:
self._retry_on_result = self.never_reject
else:
self._retry_on_result = retry_on_result
def never_stop(self, previous_attempt_number, delay_since_first_attempt_ms):
return False
def stop_after_attempt(self, previous_attempt_number, delay_since_first_attempt_ms):
return previous_attempt_number >= self._stop_max_attempt_number
def stop_after_delay(self, previous_attempt_number, delay_since_first_attempt_ms):
return delay_since_first_attempt_ms >= self._stop_max_delay
def no_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
return 0
def fixed_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
return self._wait_fixed
def random_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
return random.randint(self._wait_random_min, self._wait_random_max)
def incrementing_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
result = self._wait_incrementing_start + (self._wait_incrementing_increment * (previous_attempt_number - 1))
if result < 0:
result = 0
return result
def exponential_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
exp = 2 ** previous_attempt_number
result = self._wait_exponential_multiplier * exp
if result > self._wait_exponential_max:
result = self._wait_exponential_max
if result < 0:
result = 0
return result
def never_reject(self, result):
return False
def should_reject(self, attempt):
reject = False
if attempt.has_exception:
reject |= self._retry_on_exception(attempt.value)
else:
reject |= self._retry_on_result(attempt.value)
return reject
def call(self, fn, *args, **kwargs):
start_time = int(round(time.time() * 1000))
attempt_number = 1
while True:
try:
attempt = Attempt(fn(*args, **kwargs), False)
except BaseException as e:
attempt = Attempt(e, True)
if not self.should_reject(attempt):
return attempt.get()
# if not attempt.has_exception:
# # filter by retry_on_result() here
# if not self._retry_on_result(attempt.value):
# return attempt.value
# else:
# # filter by retry_on_exception() here
# if not self._retry_on_exception(attempt.value):
# raise RetryError(attempt_number, attempt)
delay_since_first_attempt_ms = int(round(time.time() * 1000)) - start_time
if self.stop(attempt_number, delay_since_first_attempt_ms):
raise RetryError(attempt_number, attempt)
else:
sleep = self.wait(attempt_number, delay_since_first_attempt_ms)
time.sleep(sleep / 1000.0)
attempt_number += 1
class Attempt:
def __init__(self, value, has_exception):
self.value = value
self.has_exception = has_exception
def get(self):
if self.has_exception:
raise self.value
else:
return self.value
class RetryError(Exception):
def __init__(self, failed_attempts, last_attempt):
self.failed_attempts = failed_attempts
self.last_attempt = last_attempt
def __str__(self):
return "Failed attempts: %s, Last attempt: %s" % (str(self.failed_attempts), str(self.last_attempt))
|
