diagnostics.py

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#!/usr/bin/env python
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"""
ROS diagnostics interface for the Arduino device driver node.
"""

import rospy
import threading
from diagnostic_msgs.msg import DiagnosticArray, DiagnosticStatus, KeyValue


class Diagnostics(object):
    """ ROS diagnostics interface for the Arduino device driver node. """

    def __init__(self, topic='/diagnostics'):
        self.pub = rospy.Publisher(topic, DiagnosticArray)
        self.lock = threading.RLock()
        """ Mutex lock for updating diagnostic status. """
        self.timer = rospy.Timer(rospy.Duration(1.0), self.publish)
        """ Publish diagnostic info once a second. """
        self.devices = {}
        """ Dictionary of reporting devices by name. """

    def publish(self, event):
        """ Publish current diagnostics status once a second.

        Runs in a separate timer thread, so locking is required.

        :param event: rospy.TimerEvent for this call
        """
        with self.lock:
            array = DiagnosticArray()
            array.header.stamp = event.current_real
            array.status = list(self.devices.values())
            self.pub.publish(array)

    def update(self, status):
        """ Update device status.

        :param status: New status for some device, replaces any
            previous status.
        :type status: diagnostic_msgs/DiagnosticStatus
        """
        with self.lock:
            self.devices[status.name] = status