circuitbreaker.CircuitBreaker.state() - Code Metrics - Inspection of "Merge tag '1.1.0' into develop" - fabfuel/circuitbreaker - Measure and Improve Code Quality continuously with Scrutinizer

Test Failed

Branch — develop (2ccc44)

by Fabian

created 2018-07-07 06:37 UTC

circuitbreaker.CircuitBreaker.state() A

↳ Parent: circuitbreaker

Complexity

Conditions

Size

Total Lines	5
Code Lines	5

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	4
CRAP Score	3

Importance

Changes

Metric	Value
cc	3
eloc	5
nop	1
dl	0
loc	5
rs	10
c	0
b	0
f	0
ccs	4
cts	4
cp	1
crap	3

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from __future__ import division
from __future__ import print_function
from __future__ import absolute_import

from functools import wraps
from datetime import datetime, timedelta
from typing import AnyStr, Iterable

STATE_CLOSED = 'closed'
STATE_OPEN = 'open'
STATE_HALF_OPEN = 'half_open'


class CircuitBreaker(object):
    FAILURE_THRESHOLD = 5
    RECOVERY_TIMEOUT = 30
    EXPECTED_EXCEPTION = Exception

    def __init__(self,
                 failure_threshold=None,
                 recovery_timeout=None,
                 expected_exception=None,
                 name=None):
        self._failure_count = 0
        self._failure_threshold = failure_threshold or self.FAILURE_THRESHOLD
        self._recovery_timeout = recovery_timeout or self.RECOVERY_TIMEOUT
        self._expected_exception = expected_exception or self.EXPECTED_EXCEPTION
        self._name = name
        self._state = STATE_CLOSED
        self._opened = datetime.utcnow()

    def __call__(self, wrapped):
        return self.decorate(wrapped)

    def decorate(self, function):
        """
        Applies the circuit breaker to a function
        """
        if self._name is None:
            self._name = function.__name__

        CircuitBreakerMonitor.register(self)

        @wraps(function)
        def wrapper(*args, **kwargs):
            return self.call(function, *args, **kwargs)

        return wrapper

    def call(self, func, *args, **kwargs):
        """
        Calls the decorated function and applies the circuit breaker
        rules on success or failure
        :param func: Decorated function
        """
        if self.opened:
            raise CircuitBreakerError(self)
        try:
            result = func(*args, **kwargs)
        except self._expected_exception:
            self.__call_failed()
            raise

        self.__call_succeeded()
        return result

    def __call_succeeded(self):
        """
        Close circuit after successful execution and reset failure count
        """
        self._state = STATE_CLOSED
        self._failure_count = 0

    def __call_failed(self):
        """
        Count failure and open circuit, if threshold has been reached
        """
        self._failure_count += 1
        if self._failure_count >= self._failure_threshold:
            self._state = STATE_OPEN
            self._opened = datetime.utcnow()

    @property
    def state(self):
        if self._state == STATE_OPEN and self.open_remaining <= 0:
            return STATE_HALF_OPEN
        return self._state

    @property
    def open_until(self):
        """
        The datetime, when the circuit breaker will try to recover
        :return: datetime
        """
        return self._opened + timedelta(seconds=self._recovery_timeout)

    @property
    def open_remaining(self):
        """
        Number of seconds remaining, the circuit breaker stays in OPEN state
        :return: int
        """
        return (self.open_until - datetime.utcnow()).total_seconds()

    @property
    def failure_count(self):
        return self._failure_count

    @property
    def closed(self):
        return self.state == STATE_CLOSED

    @property
    def opened(self):
        return self.state == STATE_OPEN

    @property
    def name(self):
        return self._name

    def __str__(self, *args, **kwargs):
        return self._name


class CircuitBreakerError(Exception):
    def __init__(self, circuit_breaker, *args, **kwargs):
        """
        :param circuit_breaker:
        :param args:
        :param kwargs:
        :return:
        """
        super(CircuitBreakerError, self).__init__(*args, **kwargs)
        self._circuit_breaker = circuit_breaker

    def __str__(self, *args, **kwargs):
        return 'Circuit "%s" OPEN until %s (%d failures, %d sec remaining)' % (
            self._circuit_breaker.name,
            self._circuit_breaker.open_until,
            self._circuit_breaker.failure_count,
            round(self._circuit_breaker.open_remaining)
        )


class CircuitBreakerMonitor(object):
    circuit_breakers = {}

    @classmethod
    def register(cls, circuit_breaker):
        cls.circuit_breakers[circuit_breaker.name] = circuit_breaker

    @classmethod
    def all_closed(cls):
        # type: () -> bool
        return len(list(cls.get_open())) == 0

    @classmethod
    def get_circuits(cls):
        # type: () -> Iterable[CircuitBreaker]
        return cls.circuit_breakers.values()

    @classmethod
    def get(cls, name):
        # type: (AnyStr) -> CircuitBreaker
        return cls.circuit_breakers.get(name)

    @classmethod
    def get_open(cls):
        # type: () -> Iterable[CircuitBreaker]
        for circuit in cls.get_circuits():
            if circuit.opened:
                yield circuit

    @classmethod
    def get_closed(cls):
        # type: () -> Iterable[CircuitBreaker]
        for circuit in cls.get_circuits():
            if circuit.closed:
                yield circuit


def circuit(failure_threshold=None,
            recovery_timeout=None,
            expected_exception=None,
            name=None,
            cls=CircuitBreaker):

    # if the decorator is used without parameters, the
    # wrapped function is provided as first argument
    if callable(failure_threshold):
        return cls().decorate(failure_threshold)
    else:
        return cls(
            failure_threshold=failure_threshold,
            recovery_timeout=recovery_timeout,
            expected_exception=expected_exception,
            name=name)


1		# -- coding: utf-8 --
2	1	from __future__ import unicode_literals
3	1	from __future__ import division
4	1	from __future__ import print_function
5	1	from __future__ import absolute_import
6
7	1	from functools import wraps
8	1	from datetime import datetime, timedelta
9	1	from typing import AnyStr, Iterable
10
11	1	STATE_CLOSED = 'closed'
12	1	STATE_OPEN = 'open'
13	1	STATE_HALF_OPEN = 'half_open'
14
15
16	1	class CircuitBreaker(object):
17	1	FAILURE_THRESHOLD = 5
18	1	RECOVERY_TIMEOUT = 30
19	1	EXPECTED_EXCEPTION = Exception
20
21	1	def __init__(self,
22		failure_threshold=None,
23		recovery_timeout=None,
24		expected_exception=None,
25		name=None):
26	1	self._failure_count = 0
27	1	self._failure_threshold = failure_threshold or self.FAILURE_THRESHOLD
28	1	self._recovery_timeout = recovery_timeout or self.RECOVERY_TIMEOUT
29	1	self._expected_exception = expected_exception or self.EXPECTED_EXCEPTION
30	1	self._name = name
31	1	self._state = STATE_CLOSED
32	1	self._opened = datetime.utcnow()
33
34	1	def __call__(self, wrapped):
35	1	return self.decorate(wrapped)
36
37	1	def decorate(self, function):
38		"""
39		Applies the circuit breaker to a function
40		"""
41	1	if self._name is None:
42	1	self._name = function.__name__
43
44	1	CircuitBreakerMonitor.register(self)
45
46	1	@wraps(function)
47		def wrapper(args, *kwargs):
48	1	return self.call(function, args, *kwargs)
49
50	1	return wrapper
51
52	1	def call(self, func, args, *kwargs):
53		"""
54		Calls the decorated function and applies the circuit breaker
55		rules on success or failure
56		:param func: Decorated function
57		"""
58	1	if self.opened:
59	1	raise CircuitBreakerError(self)
60	1	try:
61	1	result = func(args, *kwargs)
62	1	except self._expected_exception:
63	1	self.__call_failed()
64	1	raise
65
66	1	self.__call_succeeded()
67	1	return result
68
69	1	def __call_succeeded(self):
70		"""
71		Close circuit after successful execution and reset failure count
72		"""
73	1	self._state = STATE_CLOSED
74	1	self._failure_count = 0
75
76	1	def __call_failed(self):
77		"""
78		Count failure and open circuit, if threshold has been reached
79		"""
80	1	self._failure_count += 1
81	1	if self._failure_count >= self._failure_threshold:
82	1	self._state = STATE_OPEN
83	1	self._opened = datetime.utcnow()
84
85	1	@property
86		def state(self):
87	1	if self._state == STATE_OPEN and self.open_remaining <= 0:
88	1	return STATE_HALF_OPEN
89	1	return self._state
90
91	1	@property
92		def open_until(self):
93		"""
94		The datetime, when the circuit breaker will try to recover
95		:return: datetime
96		"""
97	1	return self._opened + timedelta(seconds=self._recovery_timeout)
98
99	1	@property
100		def open_remaining(self):
101		"""
102		Number of seconds remaining, the circuit breaker stays in OPEN state
103		:return: int
104		"""
105	1	return (self.open_until - datetime.utcnow()).total_seconds()
106
107	1	@property
108		def failure_count(self):
109	1	return self._failure_count
110
111	1	@property
112		def closed(self):
113	1	return self.state == STATE_CLOSED
114
115	1	@property
116		def opened(self):
117	1	return self.state == STATE_OPEN
118
119	1	@property
120		def name(self):
121	1	return self._name
122
123	1	def __str__(self, args, *kwargs):
124	1	return self._name
125
126
127	1	class CircuitBreakerError(Exception):
128	1	def __init__(self, circuit_breaker, args, *kwargs):
129		"""
130		:param circuit_breaker:
131		:param args:
132		:param kwargs:
133		:return:
134		"""
135	1	super(CircuitBreakerError, self).__init__(args, *kwargs)
136	1	self._circuit_breaker = circuit_breaker
137
138	1	def __str__(self, args, *kwargs):
139	1	return 'Circuit "%s" OPEN until %s (%d failures, %d sec remaining)' % (
140		self._circuit_breaker.name,
141		self._circuit_breaker.open_until,
142		self._circuit_breaker.failure_count,
143		round(self._circuit_breaker.open_remaining)
144		)
145
146
147	1	class CircuitBreakerMonitor(object):
148	1	circuit_breakers = {}
149
150	1	@classmethod
151		def register(cls, circuit_breaker):
152	1	cls.circuit_breakers[circuit_breaker.name] = circuit_breaker
153
154	1	@classmethod
155		def all_closed(cls):
156		# type: () -> bool
157	1	return len(list(cls.get_open())) == 0
158
159	1	@classmethod
160		def get_circuits(cls):
161		# type: () -> Iterable[CircuitBreaker]
162	1	return cls.circuit_breakers.values()
163
164	1	@classmethod
165		def get(cls, name):
166		# type: (AnyStr) -> CircuitBreaker
167	1	return cls.circuit_breakers.get(name)
168
169	1	@classmethod
170		def get_open(cls):
171		# type: () -> Iterable[CircuitBreaker]
172	1	for circuit in cls.get_circuits():
173	1	if circuit.opened:
174	1	yield circuit
175
176	1	@classmethod
177		def get_closed(cls):
178		# type: () -> Iterable[CircuitBreaker]
179	1	for circuit in cls.get_circuits():
180	1	if circuit.closed:
181	1	yield circuit
182
183
184	1	def circuit(failure_threshold=None,
185		recovery_timeout=None,
186		expected_exception=None,
187		name=None,
188		cls=CircuitBreaker):
189
190		# if the decorator is used without parameters, the
191		# wrapped function is provided as first argument
192	1	if callable(failure_threshold):
193	1	return cls().decorate(failure_threshold)
194		else:
195	1	return cls(
196		failure_threshold=failure_threshold,
197		recovery_timeout=recovery_timeout,
198		expected_exception=expected_exception,
199		name=name)
200

fabfuel / circuitbreaker

Branch — develop (2ccc44)

circuitbreaker.CircuitBreaker.state() A

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