我有Flask应用程序并在其中实现了RPC。
engine.py
import pickle
import pika
from databasyfacade.rpc import api
__author__ = 'Marboni'
def on_request(ch, method, props, body):
request = pickle.loads(body)
func = getattr(api, request['func'])
try:
result = func(*request['args'])
except Exception, e:
response = {
'status': 'ERROR',
'error': e
}
else:
response = {
'status': 'OK',
'result': result
}
ch.basic_publish(exchange='',
routing_key=props.reply_to,
properties=pika.BasicProperties(
correlation_id=props.correlation_id
),
body=pickle.dumps(response)
)
ch.basic_ack(delivery_tag=method.delivery_tag)
def init(host):
connection = pika.BlockingConnection(pika.ConnectionParameters(host))
channel = connection.channel()
channel.queue_declare(queue='facade_rpc')
channel.basic_qos(prefetch_count=1)
channel.basic_consume(on_request, queue='facade_rpc')
api.py
from databasyfacade.services import profiles_service
__author__ = 'Marboni'
def profile(user_id):
return profiles_service.profile(user_id)
当Flask应用程序初始化时，它会运行方法init(host)。
现在我需要测试我的应用程序如何响应RPC调用。所以我写了以下RPC客户端：
client.py
import pickle
import uuid
import pika
__author__ = 'Marboni'
class RpcClient(object):
def __init__(self, host):
self.connection = pika.BlockingConnection(pika.ConnectionParameters(host=host))
self.channel = self.connection.channel()
result = self.channel.queue_declare(exclusive=True)
self.callback_queue = result.method.queue
self.channel.basic_consume(self.on_response, no_ack=True, queue=self.callback_queue)
def on_response(self, ch, method, props, body):
if self.corr_id == props.correlation_id:
self.response = body
def call(self, func, *args):
request = {
'func': func,
'args': args
}
self.response = None
self.corr_id = str(uuid.uuid4())
self.channel.basic_publish(exchange='',
routing_key='facade_rpc',
properties=pika.BasicProperties(
reply_to = self.callback_queue,
correlation_id = self.corr_id,
),
body=pickle.dumps(request))
while self.response is None:
self.connection.process_data_events()
response = pickle.loads(self.response)
if response['status'] == 'ERROR':
e = response['error']
raise e
else:
return response['result']
然后我根据Flask-Testing框架编写了测试。它在每个测试方法之间初始化Flask应用程序，因此我们可以与它进行交互。
tests.py
from databasyfacade.rpc import RpcClient
from databasyfacade.testing import DatabasyTest, fixtures
from databasyfacade.testing.testdata import UserData, ProfileData
__author__ = 'Marboni'
class RpcTest(DatabasyTest):
@fixtures(UserData, ProfileData)
def test_profile(self, data):
rpc = RpcClient(self.app.config['RABBITMQ_HOST'])
profile = rpc.call('profile', ProfileData.hero.user_id)
self.assertIsNotNone(profile)
self.assertEqual(ProfileData.hero.email, profile.email)
拨打电话时此测试会挂起。它在这里无限迭代：
来自client.py
while self.response is None:
self.connection.process_data_events()
这意味着客户端上的on_response()方法从未调用过。
如果我用CTRL-C中断测试，我会看到以下stacktrace：
Traceback (most recent call last):
File "../env/bin/nosetests", line 8, in <module>
load_entry_point('nose==1.3.0', 'console_scripts', 'nosetests')()
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/core.py", line 118, in __init__
**extra_args)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/main.py", line 95, in __init__
self.runTests()
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/core.py", line 197, in runTests
result = self.testRunner.run(self.test)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/core.py", line 61, in run
test(result)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/suite.py", line 65, in __call__
return self.run(*args, **kwds)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 74, in run
test(result)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
return self.run(*arg, **kw)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/suite.py", line 223, in run
test(orig)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/case.py", line 45, in __call__
return self.run(*arg, **kwarg)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/case.py", line 133, in run
self.runTest(result)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/nose/case.py", line 151, in runTest
test(result)
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/flask_testing.py", line 72, in __call__
self._pre_setup()
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/flask_testing.py", line 80, in _pre_setup
self.app = self.create_app()
File "/Users/Marboni/Projects/Databasy/databasy-facade/databasyfacade/databasyfacade/testing/__init__.py", line 12, in create_app
return app.create_app()
File "/Users/Marboni/Projects/Databasy/databasy-facade/databasyfacade/databasyfacade/app.py", line 75, in create_app
init_rpc(app)
File "/Users/Marboni/Projects/Databasy/databasy-facade/databasyfacade/databasyfacade/app.py", line 63, in init_rpc
rpc.init(app.config['RABBITMQ_HOST'])
File "/Users/Marboni/Projects/Databasy/databasy-facade/databasyfacade/databasyfacade/rpc/engine.py", line 39, in init
channel.basic_consume(on_request, queue='facade_rpc')
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/channel.py", line 220, in basic_consume
{'consumer_tag': consumer_tag})])
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 1104, in _rpc
self._wait_on_response(method_frame))
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 1124, in _send_method
self.connection.process_data_events()
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 215, in process_data_events
if self._handle_read():
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 327, in _handle_read
if self._read_poller.ready():
File "/Users/Marboni/Projects/Databasy/databasy-facade/env/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 66, in ready
self.poll_timeout)
KeyboardInterrupt
我尝试运行应用程序并从单独的脚本访问它：
#!/usr/bin/env python
from databasyfacade.rpc.client import RpcClient
rpc = RpcClient('localhost')
profile = rpc.call('profile', 4L)
print profile.email
正如您所看到的，代码与测试中的代码相同，但在这种情况下它可以正常工作。
这个问题的原因是什么？可能是，因为Flask-Testing在一个进程中运行应用程序和客户端？如何检查/写出正确的测试？
答案 0 :(得分：1)
我找到了原因，它与MQ无关。使用带有scoped_session的SQLAlchemy删除方法访问的数据库。在我完成会话properly之后问题消失了：
Session.remove()