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# pylint: disable=missing-docstring
# pylint: enable=missing-docstring
# Copyright 2017 Spotify AB
#
# 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.
from __future__ import absolute_import
import pickle
import six
import threading
import uuid
import zmq
from six.moves import queue
from .util import batch_iterable
class ZeroBase(object): # pylint: disable=too-few-public-methods
"""
Base class for ZeroMQ communication.
Parameters
----------
push_address : str
Address to which messages are pushed.
pull_address : str
Address from which messages are pulled.
dumps : callable
Function to serialize messages.
loads : callable
Function to deserialize messages.
"""
IDENTIFIER_SIZE = 16
def __init__(self, push_address, pull_address, method, dumps=None, loads=None): # pylint: disable=too-many-arguments
self.push_address = push_address
self.pull_address = pull_address
self.context = zmq.Context()
self.pusher = self.context.socket(zmq.PUSH) # pylint: disable=no-member
try:
getattr(self.pusher, method)(self.push_address)
except zmq.ZMQError as ex: # pragma: no cover
raise RuntimeError("failed to %s pusher to '%s': %s" % (method, self.push_address, ex))
self.puller = self.context.socket(zmq.PULL) # pylint: disable=no-member
try:
getattr(self.puller, method)(self.pull_address)
except zmq.ZMQError as ex: # pragma: no cover
raise RuntimeError("failed to %s puller to '%s': %s" % (method, self.pull_address, ex))
self.dumps = dumps or pickle.dumps
self.loads = loads or pickle.loads
def __enter__(self):
return self
def __exit__(self, *_):
self.close()
def close(self):
"""
Close the associated sockets.
"""
self.pusher.close()
self.puller.close()
class Consumer(ZeroBase):
"""
Data consumer.
Parameters
----------
push_address : str
Address to which messages are pushed.
pull_address : str
Address from which messages are pulled.
dumps : callable
Function to serialize messages (defaults to `pickle.dumps`).
loads : callable
Function to deserialize messages (defaults to `pickle.loads`).
"""
def __init__(self, push_address, pull_address, dumps=None, loads=None): # pylint: disable=too-many-arguments
super(Consumer, self).__init__(push_address, pull_address, 'bind', dumps, loads)
def push_message(self, message, identifier_queue=None, command=b'\x00'):
"""
Push a message.
Parameters
----------
message : object
Message to be pushed.
identifier_queue : queue.Queue
Queue used to keep track of the order of messages.
command : bytes
Command to execute on the remote (`0x00` to apply the target to the message,
`0x01` to map the target over the message).
Returns
-------
identifier : bytes
Unique identifier of the message.
"""
identifier = uuid.uuid4().bytes
if identifier_queue:
identifier_queue.put(identifier, timeout=1)
self.pusher.send(b''.join([identifier, command, self.dumps(message)]))
return identifier
def push_messages(self, messages, stop_event, identifier_queue, command=b'\x00'):
"""
Push a sequence of messages.
Parameters
----------
messages : iterable
Sequence of messages to push.
stop_event : threading.Event
Event used to stop pushing messages.
identifier_queue : queue.Queue
Queue used to keep track of the order of messages.
command : bytes
Command to execute on the remote (`0x00` to apply the target to the message,
`0x01` to map the target over the message).
"""
messages = iter(messages)
message = next(messages)
while not stop_event.is_set():
try:
self.push_message(message, identifier_queue, command)
message = next(messages)
except queue.Full: # pragma: no cover
pass
except StopIteration:
identifier_queue.put(None)
break
def wait_for_message(self, identifier, cache):
"""
Wait for a specific message.
Parameters
----------
identifier : bytes
Unique identifier of the message to wait for.
cache : dict
Cache for storing messages.
Returns
-------
payload : object
Response payload.
"""
while identifier not in cache:
message = self.puller.recv()
_identifier = message[:self.IDENTIFIER_SIZE]
status = message[self.IDENTIFIER_SIZE]
payload = self.loads(message[1 + self.IDENTIFIER_SIZE:])
if status != b'\x00':
raise payload
else:
cache[_identifier] = payload
return cache.pop(identifier)
def get_message(self, message, command=b'\x00'):
"""
Push a message and wait for the response.
Parameters
----------
message : object
Message to be pushed.
command : bytes
Command to execute on the remote (`0x00` to apply the target to the message,
`0x01` to map the target over the message).
Returns
-------
payload : object
Response payload.
"""
identifier = self.push_message(message, command=command)
return self.wait_for_message(identifier, {})
@staticmethod
def build_message(fetches, context, **kwargs):
"""
Build a message to be processed by a remote graph.
"""
for key in context:
if not isinstance(key, six.string_types):
raise TypeError("context keys must be strings but got '%s'" % key)
# Add the keyword arguments
for key, value in kwargs.items():
if key in context:
raise ValueError("duplicate value for key '%s'" % key)
context[key] = value
return {
'fetches': fetches,
'context': context,
}
def map_messages(self, messages, max_messages, command=b'\x00'):
"""
Push a sequence of messages and wait for the responses.
Parameters
----------
messages : iterable
Sequence of messages to push.
max_messages : int
Maximum number of messages that are published at any time.
command : bytes
Command to execute on the remote (`0x00` to apply the target to the message,
`0x01` to map the target over the message).
Yields
------
payload : object
Response payload.
"""
if max_messages <= 0:
raise ValueError('`max_messages` must be positive but got %s' % max_messages)
try:
# Publish all the messages in a background thread
identifier_queue = queue.Queue(max_messages)
stop_event = threading.Event()
thread = threading.Thread(
target=self.push_messages,
args=(messages, stop_event, identifier_queue, command)
)
thread.start()
cache = {}
while True:
# Get the next identifier
identifier = identifier_queue.get()
if identifier is None:
return
yield self.wait_for_message(identifier, cache)
except: # pragma: no cover
stop_event.set()
raise
finally:
# Wait for the publishing thread to exit
thread.join()
def __call__(self, fetches, context=None, **kwargs):
"""
Evaluate one or more operations remotely given a context.
Parameters
----------
fetches : list[str or Operation] or str or Operation
One or more `Operation` instances or names to evaluate.
context : dict or None
Context in which to evaluate the operations.
kwargs : dict
Additional context information keyed by variable name.
Returns
-------
values : tuple[object]
Output of the operations given the context.
"""
return self.get_message(self.build_message(fetches, context or {}, **kwargs))
def map(self, fetches, contexts, batch_size=1, max_messages=1, **kwargs):
"""
Evaluate one or more operations remotely given a sequence of contexts.
Parameters
----------
fetches : list[str or Operation] or str or Operation
One or more `Operation` instances or names to evaluate.
contexts : list[dict or None]
Sequence of contexts in which to evaluate the operations.
batch_size : int
Number of items per batch.
max_messages : int
Maximum number of messages that are published at any time. Increasing the maximum
number of messages generally improves performance but will consume more memory.
kwargs : dict
Additional context information keyed by variable name that is shared across all
contexts.
"""
messages = map(lambda context: self.build_message(fetches, context, **kwargs), contexts)
if batch_size > 1:
messages = batch_iterable(messages, batch_size)
command = b'\x01'
else:
command = b'\x00'
return self.map_messages(messages, max_messages, command)
class Processor(ZeroBase): # pragma: no cover
"""
Data processor.
Parameters
----------
push_address : str
Address to which messages are pushed.
pull_address : str
Address from which messages are pulled.
target : callable
Function to process incoming messages.
dumps : callable
Function to serialize messages.
loads : callable
Function to deserialize messages.
"""
def __init__(self, push_address, pull_address, target, dumps=None, loads=None): # pylint: disable=too-many-arguments
super(Processor, self).__init__(push_address, pull_address, 'connect', dumps, loads)
self.target = target
def run(self):
"""
Run the data producer event loop.
"""
while True:
message = self.puller.recv()
identifier = message[:self.IDENTIFIER_SIZE]
command = message[self.IDENTIFIER_SIZE]
status = b'\x00'
payload = None
try:
payload = self.loads(message[self.IDENTIFIER_SIZE + 1:])
try:
if command == b'\x00':
payload = self.target(payload)
elif command == b'\x01':
payload = tuple(map(self.target, payload))
else:
status = b'\x03'
payload = KeyError("invalid command code: %s" % command)
except Exception as ex: # pylint: disable=broad-except
status = b'\x02'
payload = ex
except Exception as ex: # pylint: disable=broad-except
status = b'\x01'
payload = ex
self.pusher.send(b''.join([identifier, status, self.dumps(payload)]))
@classmethod
def from_graph(cls, push_address, pull_address, graph, dumps=None, loads=None): # pylint: disable=too-many-arguments
"""
Create a producer from a graph.
Deserialized messages must be dictionaries with `fetches` and `context` keys.
Parameters
----------
push_address : str
Address to which messages are pushed.
pull_address : str
Address from which messages are pulled.
graph : Graph
Graph to process messages.
dumps : callable
Function to serialize messages.
loads : callable
Function to deserialize messages.
"""
return cls(push_address, pull_address,
lambda payload: graph(payload['fetches'], payload['context']),
dumps, loads)