adding first stable implementation, reasonable passing test coverage

1 files changed, 181 insertions, 0 deletions

diff --git a/retrying.py b/retrying.py
new file mode 100644
index 0000000..6ecb708
--- /dev/null
+++ b/retrying.py
@@ -0,0 +1,181 @@
+## 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))