wally/sensors/api.py

import Queue
import threading
from contextlib import contextmanager

from .deploy_sensors import (deploy_and_start_sensors,
                             stop_and_remove_sensors)
from .protocol import create_protocol, Timeout


__all__ = ['Empty', 'recv_main', 'start_monitoring',
           'deploy_and_start_sensors', 'SensorConfig']


Empty = Queue.Empty


class SensorConfig(object):
    def __init__(self, conn, url, sensors):
        self.conn = conn
        self.url = url
        self.sensors = sensors


def recv_main(proto, data_q, cmd_q):
    while True:
        try:
            data_q.put(proto.recv(0.1))
        except Timeout:
            pass

        try:
            val = cmd_q.get(False)

            if val is None:
                return

        except Queue.Empty:
            pass


@contextmanager
def start_monitoring(uri, configs):
    deploy_and_start_sensors(uri, configs)
    try:
        data_q = Queue.Queue()
        cmd_q = Queue.Queue()
        proto = create_protocol(uri, receiver=True)
        th = threading.Thread(None, recv_main, None, (proto, data_q, cmd_q))
        th.daemon = True
        th.start()

        try:
            yield data_q
        finally:
            cmd_q.put(None)
            th.join()
    finally:
        stop_and_remove_sensors(configs)