def simple_app(environ, start_response):
"""Simple WSGI application."""
setup_testing_defaults(environ)
# Identify log and section from request.
path_info = environ["PATH_INFO"]
try:
section_id = path_info.strip("/").split("/")[-1]
except ValueError:
# Start response.
status = "404 Not Found"
headers = [("Content-type", "text/plain; charset=utf-8")]
start_response(status, headers)
return []
# Select the notification log.
notification_log = self.create_notification_log(section_size)
# Get serialized section.
json_encoder = ObjectJSONEncoder(separators=JSON_SEPARATORS)
view = NotificationLogView(notification_log, json_encoder)
resource = view.present_resource(section_id)
# Todo: Maybe redirect if the section ID is a mismatch, so
# the URL is good for cacheing.
# Start response.
status = "200 OK"
headers = [("Content-type", "text/plain; charset=utf-8")]
start_response(status, headers)
# Return a list of lines.
return [(line + "\n").encode("utf8")
for line in resource.split("\n")]
def hash_object(json_encoder: ObjectJSONEncoder, obj: dict) -> str:
"""
Calculates SHA-256 hash of JSON encoded 'obj'.
:param json_encoder: JSON encoder object.
:param obj: Object to be hashed.
:return: SHA-256 as hexadecimal string.
:rtype str
"""
s = json_encoder.encode((obj, SALT_FOR_DATA_INTEGRITY))
return hashlib.sha256(s).hexdigest()
def setUp(self):
self.encoder = ObjectJSONEncoder(sort_keys=True)
self.decoder = ObjectJSONDecoder()
class DomainEvent(Upcastable, ActualOccasion, Generic[TEntity]):
"""
Base class for domain model events.
Implements methods to make instances read-only,
comparable for equality in Python, and have
recognisable representations.Custom
To make domain events hashable, this class also
implements a method to create a cryptographic hash
of the state of the event.
"""
__json_encoder_v2__ = ObjectJSONEncoder(sort_keys=True)
__json_encoder_v1__ = transcoding_v1.ObjectJSONEncoder(sort_keys=True)
__notifiable__ = True
def __init__(self, **kwargs: Any):
"""
Initialises event attribute values directly from constructor kwargs.
"""
super().__init__()
self.__dict__.update(kwargs)
def __repr__(self) -> str:
"""
Creates a string representing the type and attribute values of the event.
:rtype: str
"""
sorted_items = tuple(sorted(self.__dict__.items()))
args_strings = ("{0}={1!r}".format(*item) for item in sorted_items)
args_string = ", ".join(args_strings)
return "{}({})".format(self.__class__.__qualname__, args_string)
def __mutate__(self, obj: Optional[TEntity]) -> Optional[TEntity]:
"""
Updates 'obj' with values from 'self'.
Calls the 'mutate()' method.
Can be extended, but subclasses must call super
and return an object to their caller.
:param obj: object (normally a domain entity) to be mutated
:return: mutated object
"""
if obj is not None:
self.mutate(obj)
return obj
def mutate(self, obj: TEntity) -> None:
"""
Updates ("mutates") given 'obj'.
Intended to be overridden by subclasses, as the most
concise way of coding a default projection of the event
(for example into the state of a domain entity).
The advantage of implementing a default projection
using this method rather than __mutate__ is that you
don't need to call super or return a value.
:param obj: domain entity to be mutated
"""
def __setattr__(self, key: Any, value: Any) -> None:
"""
Inhibits event attributes from being updated by assignment.
"""
raise AttributeError("DomainEvent attributes are read-only")
def __eq__(self, other: object) -> bool:
"""
Tests for equality of two event objects.
:rtype: bool
"""
return isinstance(other,
DomainEvent) and self.__hash__() == other.__hash__()
# Todo: Do we need this in Python 3?
def __ne__(self, other: object) -> bool:
"""
Negates the equality test.
:rtype: bool
"""
return not (self == other)
def __hash__(self) -> int:
"""
Computes a Python integer hash for an event.
Supports Python equality and inequality comparisons.
:return: Python integer hash
:rtype: int
"""
attrs = self.__dict__.copy()
# Involve the topic in the hash, so that different types
# with same attribute values have different hash values.
attrs["__event_topic__"] = get_topic(type(self))
# Calculate the cryptographic hash of the event.
sha256_hash = self.__hash_object_v2__(attrs)
# Return the Python hash of the cryptographic hash.
return hash(sha256_hash)
@classmethod
def __hash_object_v2__(cls, obj: dict) -> str:
"""
Calculates SHA-256 hash of JSON encoded 'obj'.
:param obj: Object to be hashed.
:return: SHA-256 as hexadecimal string.
:rtype: str
"""
return hash_object(cls.__json_encoder_v2__, obj)
@classmethod
def __hash_object_v1__(cls, obj: dict) -> str:
"""
Calculates SHA-256 hash of JSON encoded 'obj'.
:param obj: Object to be hashed.
:return: SHA-256 as hexadecimal string.
:rtype: str
"""
return hash_object(cls.__json_encoder_v1__, obj)
def test_encode(self):
encoder = ObjectJSONEncoder()
value = 1
expect = '1'
self.assertEqual(encoder.encode(value), expect)
value = datetime.datetime(2011, 1, 1, 1, 1, 1)
expect = '{"ISO8601_datetime": "2011-01-01T01:01:01.000000"}'
self.assertEqual(encoder.encode(value), expect)
value = datetime.datetime(2011, 1, 1, 1, 1, 1, tzinfo=utc_timezone)
expect = '{"ISO8601_datetime": "2011-01-01T01:01:01.000000+0000"}'
self.assertEqual(encoder.encode(value), expect)
value = datetime.date(2011, 1, 1)
expect = '{"ISO8601_date": "2011-01-01"}'
self.assertEqual(expect, encoder.encode(value))
value = datetime.time(23, 59, 59, 123456)
expect = '{"ISO8601_time": "23:59:59.123456"}'
self.assertEqual(encoder.encode(value), expect)
value = Decimal('59.123456')
expect = '{"__decimal__": "59.123456"}'
self.assertEqual(encoder.encode(value), expect)
value = NAMESPACE_URL
expect = '{"UUID": "6ba7b8119dad11d180b400c04fd430c8"}'
self.assertEqual(encoder.encode(value), expect)
value = Object(NAMESPACE_URL)
self.assertEqual(
value.__class__.__module__, 'eventsourcing.tests.test_transcoding',
"Module does not have full path, Python 2.7 issue with unittest"
" (need to run test from root dir")
expect = (
'{"__class__": {"state": {"a": {"UUID": "6ba7b8119dad11d180b400c04fd430c8"}}, '
'"topic": "eventsourcing.tests.test_transcoding#Object"}}')
self.check_encoded_value(encoder, value, expect)
value = deque()
expect = '{"__deque__": []}'
self.assertEqual(encoder.encode(value), expect)
# Check defers to base class to raise TypeError.
# - a type isn't supported at the moment, hence this test works
with self.assertRaises(TypeError):
encoder.encode(object)
def __init__(self):
self.channel = None
self.json_encoder = ObjectJSONEncoder()
self.json_decoder = ObjectJSONDecoder()
class ProcessorClient(object):
def __init__(self):
self.channel = None
self.json_encoder = ObjectJSONEncoder()
self.json_decoder = ObjectJSONDecoder()
def connect(self, address, timeout=5):
"""
Connect to client to server at given address.
Calls ping() until it gets a response, or timeout is reached.
"""
self.close()
self.channel = grpc.insecure_channel(address)
self.stub = ProcessorStub(self.channel)
timer_started = datetime.now()
while True:
# Ping until get a response.
try:
self.ping()
except _InactiveRpcError:
if timeout is not None:
timer_duration = (datetime.now() -
timer_started).total_seconds()
if timer_duration > 15:
raise Exception("Timed out trying to connect to %s" %
address)
else:
continue
else:
break
# def __enter__(self):
# return self
#
# def __exit__(self, exc_type, exc_val, exc_tb):
# self.close()
#
def close(self):
"""
Closes the client's GPRC channel.
"""
if self.channel is not None:
self.channel.close()
def ping(self):
"""
Sends a Ping request to the server.
"""
request = Empty()
response = self.stub.Ping(request, timeout=5)
# def follow(self, upstream_name, upstream_address):
# request = FollowRequest(
# upstream_name=upstream_name, upstream_address=upstream_address
# )
# response = self.stub.Follow(request, timeout=5,)
def prompt(self, upstream_name):
"""
Prompts downstream server with upstream name, so that downstream
process and promptly pull new notifications from upstream process.
"""
request = PromptRequest(upstream_name=upstream_name)
response = self.stub.Prompt(request, timeout=5)
def get_notifications(self, section_id):
"""
Gets a section of event notifications from server.
"""
request = NotificationsRequest(section_id=section_id)
notifications_reply = self.stub.GetNotifications(request, timeout=5)
assert isinstance(notifications_reply, NotificationsReply)
return notifications_reply.section
def lead(self, application_name, address):
"""
Requests a process to connect and then send prompts to given address.
"""
request = LeadRequest(downstream_name=application_name,
downstream_address=address)
response = self.stub.Lead(request, timeout=5)
def call_application(self, method_name, *args, **kwargs):
"""
Calls named method on server's application with given args.
"""
request = CallRequest(
method_name=method_name,
args=self.json_encoder.encode(args),
kwargs=self.json_encoder.encode(kwargs),
)
response = self.stub.CallApplicationMethod(request, timeout=5)
return self.json_decoder.decode(response.data)
def __init__(
self,
application_topic,
pipeline_id,
infrastructure_topic,
setup_table,
address,
upstreams,
downstreams,
push_prompt_interval,
):
super(ProcessorServer, self).__init__()
# Make getting notifications more efficient.
notificationlog.USE_REGULAR_SECTIONS = False
notificationlog.DEFAULT_SECTION_SIZE = 100
self.has_been_stopped = Event()
signal(SIGINT, self.stop)
self.application_class: Type[ProcessApplication] = resolve_topic(
application_topic)
self.pipeline_id = pipeline_id
self.application_name = self.application_class.create_name()
infrastructure_class: Type[
ApplicationWithConcreteInfrastructure] = resolve_topic(
infrastructure_topic)
self.application = self.application_class.mixin(
infrastructure_class=infrastructure_class)(
pipeline_id=self.pipeline_id, setup_table=setup_table)
self.address = address
self.json_encoder = ObjectJSONEncoder()
self.json_decoder = ObjectJSONDecoder()
self.upstreams = upstreams
self.downstreams = downstreams
self.prompt_events = {}
self.push_prompt_interval = push_prompt_interval
self.notification_log_view = NotificationLogView(
self.application.notification_log,
json_encoder=ObjectJSONEncoder(),
)
for upstream_name in self.upstreams:
self.prompt_events[upstream_name] = Event()
# self.prompt_events[upstream_name].set()
self.downstream_prompt_event = Event()
subscribe(self._set_downstream_prompt_event, is_prompt_to_pull)
self.serve()
self.clients: Dict[str, ProcessorClient] = {}
self.clients_lock = Lock()
start_client_threads = []
remotes = {}
remotes.update(self.upstreams)
remotes.update(self.downstreams)
for name, address in remotes.items():
thread = StartClient(self.clients, name, address)
thread.setDaemon(True)
thread.start()
start_client_threads.append(thread)
for thread in start_client_threads:
thread.join()
# logging.info("%s connected to %s" % (self.application_name, thread.name))
self.push_prompts_thread = Thread(target=self._push_prompts)
self.push_prompts_thread.setDaemon(True)
self.push_prompts_thread.start()
# self.count_of_events = 0
self.pull_notifications_threads = {}
self.unprocessed_domain_event_queue = Queue()
for upstream_name, upstream_address in self.upstreams.items():
thread = PullNotifications(
prompt_event=self.prompt_events[upstream_name],
reader=NotificationLogReader(
RemoteNotificationLog(
client=self.clients[upstream_name],
json_decoder=ObjectJSONDecoder(),
section_size=self.application.notification_log.
section_size,
)),
process_application=self.application,
event_queue=self.unprocessed_domain_event_queue,
upstream_name=upstream_name,
has_been_stopped=self.has_been_stopped,
)
thread.setDaemon(True)
self.pull_notifications_threads[upstream_name] = thread
self.process_events_thread = Thread(target=self._process_events)
self.process_events_thread.setDaemon(True)
self.process_events_thread.start()
# Start the threads.
for thread in self.pull_notifications_threads.values():
thread.start()
# Wait for termination.
self.wait_for_termination()
class ProcessorServer(ProcessorServicer):
def __init__(
self,
application_topic,
pipeline_id,
infrastructure_topic,
setup_table,
address,
upstreams,
downstreams,
push_prompt_interval,
):
super(ProcessorServer, self).__init__()
# Make getting notifications more efficient.
notificationlog.USE_REGULAR_SECTIONS = False
notificationlog.DEFAULT_SECTION_SIZE = 100
self.has_been_stopped = Event()
signal(SIGINT, self.stop)
self.application_class: Type[ProcessApplication] = resolve_topic(
application_topic)
self.pipeline_id = pipeline_id
self.application_name = self.application_class.create_name()
infrastructure_class: Type[
ApplicationWithConcreteInfrastructure] = resolve_topic(
infrastructure_topic)
self.application = self.application_class.mixin(
infrastructure_class=infrastructure_class)(
pipeline_id=self.pipeline_id, setup_table=setup_table)
self.address = address
self.json_encoder = ObjectJSONEncoder()
self.json_decoder = ObjectJSONDecoder()
self.upstreams = upstreams
self.downstreams = downstreams
self.prompt_events = {}
self.push_prompt_interval = push_prompt_interval
self.notification_log_view = NotificationLogView(
self.application.notification_log,
json_encoder=ObjectJSONEncoder(),
)
for upstream_name in self.upstreams:
self.prompt_events[upstream_name] = Event()
# self.prompt_events[upstream_name].set()
self.downstream_prompt_event = Event()
subscribe(self._set_downstream_prompt_event, is_prompt_to_pull)
self.serve()
self.clients: Dict[str, ProcessorClient] = {}
self.clients_lock = Lock()
start_client_threads = []
remotes = {}
remotes.update(self.upstreams)
remotes.update(self.downstreams)
for name, address in remotes.items():
thread = StartClient(self.clients, name, address)
thread.setDaemon(True)
thread.start()
start_client_threads.append(thread)
for thread in start_client_threads:
thread.join()
# logging.info("%s connected to %s" % (self.application_name, thread.name))
self.push_prompts_thread = Thread(target=self._push_prompts)
self.push_prompts_thread.setDaemon(True)
self.push_prompts_thread.start()
# self.count_of_events = 0
self.pull_notifications_threads = {}
self.unprocessed_domain_event_queue = Queue()
for upstream_name, upstream_address in self.upstreams.items():
thread = PullNotifications(
prompt_event=self.prompt_events[upstream_name],
reader=NotificationLogReader(
RemoteNotificationLog(
client=self.clients[upstream_name],
json_decoder=ObjectJSONDecoder(),
section_size=self.application.notification_log.
section_size,
)),
process_application=self.application,
event_queue=self.unprocessed_domain_event_queue,
upstream_name=upstream_name,
has_been_stopped=self.has_been_stopped,
)
thread.setDaemon(True)
self.pull_notifications_threads[upstream_name] = thread
self.process_events_thread = Thread(target=self._process_events)
self.process_events_thread.setDaemon(True)
self.process_events_thread.start()
# Start the threads.
for thread in self.pull_notifications_threads.values():
thread.start()
# Wait for termination.
self.wait_for_termination()
def _set_downstream_prompt_event(self, event):
# logging.info(
# "Setting downstream prompt event on %s for %s"
# % (self.application_name, event)
# )
self.downstream_prompt_event.set()
def _push_prompts(self) -> None:
# logging.info("Started push prompts thread")
while not self.has_been_stopped.is_set():
try:
self.__push_prompts()
sleep(self.push_prompt_interval)
except Exception as e:
if not self.has_been_stopped.is_set():
logging.error(traceback.format_exc())
logging.error(
"Continuing after error in 'push prompts' thread: %s",
e)
sleep(1)
def __push_prompts(self):
self.downstream_prompt_event.wait()
self.downstream_prompt_event.clear()
# logging.info("Pushing prompts from %s" % self.application_name)
for downstream_name in self.downstreams:
client = self.clients[downstream_name]
if not self.has_been_stopped.is_set():
client.prompt(self.application_name)
def _process_events(self) -> None:
while not self.has_been_stopped.is_set():
try:
self.__process_events()
except Exception as e:
logging.error(traceback.format_exc())
logging.error(
"Continuing after error in 'process events' thread:", e)
sleep(1)
def __process_events(self):
unprocessed_item = self.unprocessed_domain_event_queue.get()
self.unprocessed_domain_event_queue.task_done()
if unprocessed_item is None:
return
else:
# Process domain event.
domain_event, notification_id, upstream_name = unprocessed_item
# logging.info("Unprocessed event: %s" % domain_event)
new_events, new_records = self.application.process_upstream_event(
domain_event, notification_id, upstream_name)
# Publish a prompt if there are new notifications.
if any([event.__notifiable__ for event in new_events]):
self.application.publish_prompt()
def serve(self):
"""
Starts gRPC server.
"""
self.executor = futures.ThreadPoolExecutor(max_workers=10)
self.server = grpc.server(self.executor)
# logging.info(self.application_class)
add_ProcessorServicer_to_server(self, self.server)
self.server.add_insecure_port(self.address)
self.server.start()
def wait_for_termination(self):
"""
Runs until termination of process.
"""
self.server.wait_for_termination()
def Ping(self, request, context):
return Empty()
# def Follow(self, request, context):
# upstream_name = request.upstream_name
# upstream_address = request.upstream_address
# self.follow(upstream_name, upstream_address)
# return Empty()
#
# def follow(self, upstream_name, upstream_address):
# """"""
# # logging.debug("%s is following %s" % (self.application_name, upstream_name))
# self.clients[upstream_name].lead(self.application_name, self.address)
def Lead(self, request, context):
downstream_name = request.downstream_name
downstream_address = request.downstream_address
self.lead(downstream_name, downstream_address)
return Empty()
def lead(self, downstream_name, downstream_address):
"""
Starts client and registers downstream to receive prompts.
"""
# logging.debug("%s is leading %s" % (self.application_name, downstream_name))
thread = StartClient(self.clients, downstream_name, downstream_address)
thread.setDaemon(True)
thread.start()
thread.join()
if thread.error:
raise Exception(
"Couldn't lead '%s' on address '%s': %s" %
(downstream_name, downstream_address, thread.error))
else:
self.downstreams[downstream_name] = downstream_address
def start_client(self, name, address):
"""
Starts client connected to given address.
"""
if name not in self.clients:
self.clients[name] = ProcessorClient()
self.clients[name].connect(address)
def Prompt(self, request, context):
upstream_name = request.upstream_name
self.prompt(upstream_name)
return Empty()
def prompt(self, upstream_name):
"""
Set prompt event for upstream name.
"""
self.prompt_events[upstream_name].set()
def GetNotifications(self, request, context):
section_id = request.section_id
section = self.get_notification_log_section(section_id)
return NotificationsReply(section=section)
def get_notification_log_section(self, section_id):
"""
Returns section for given section ID.
"""
return self.notification_log_view.present_resource(
section_id=section_id)
def CallApplicationMethod(self, request, context):
method_name = request.method_name
# logging.info("Call application method: %s" % method_name)
args = self.json_decoder.decode(request.args)
kwargs = self.json_decoder.decode(request.kwargs)
method = getattr(self.application, method_name)
return_value = method(*args, **kwargs)
return CallReply(data=self.json_encoder.encode(return_value))
def stop(self, *args):
"""
Stops the gRPC server.
"""
# logging.debug("Stopping....")
self.has_been_stopped.set()
self.server.stop(grace=1)