node_proxy.py

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# Author: Isaac Saito

import time
import threading

from roslaunch import node_args, nodeprocess
import rospy


class Polling(threading.Thread):

    def __init__(self, parent):
        super(Polling, self).__init__()
        self._parent = parent

    def run(self):
        while True:
            rospy.logdebug('Proc={} Died? {}'.format(self._parent.get_proc_name(),
                                                     self._parent.has_died()))
            time.sleep(1.0)


class NodeProxy(object):

    '''
    Works as a proxy between ROS Node
    (more in particular, roslaunch.nodeprocess) & GUI.
    '''

    __slots__ = ['_run_id', 'master_uri', 'config', '_process']

    def __init__(self, run_id, master_uri, config):
        self._run_id = run_id
        self.master_uri = master_uri
        self.config = config

        # @type: roslaunch.nodeprocess.LocalProcess
        self._process = self.recreate_process()

    # LocalProcess.is_alive() does not do what you would expect
    def is_running(self):
        rospy.logdebug('BEFORE started={}, stopped={} alive={}'.format(
            self._process.started,
            self._process.stopped,
            self._process.is_alive()))
        return self._process.started and not self._process.stopped
        # and self._process.is_alive()
        #  is_alive() returns False once nodeprocess was stopped.

    def has_died(self):
        rospy.logdebug('Proc={} started={}, stopped={}, is_alive={}'.format(
            self.get_proc_name(), self._process.started, self._process.stopped,
            self._process.is_alive()))

        return (self._process.started and not self._process.stopped
                and not self._process.is_alive())

    def recreate_process(self):
        '''
        Create and set roslaunch.nodeprocess.LocalProcess to member variable.
        @rtype: roslaunch.nodeprocess.LocalProcess
        '''
        _local_process = nodeprocess.LocalProcess
        try:
            _local_process = nodeprocess.create_node_process(
                self._run_id, self.config, self.master_uri)
        except node_args.NodeParamsException as e:
            rospy.logerr('roslaunch failed to load the node. {}'.format(
                e.message))
            # TODO: Show msg on GUI that the node wasn't loaded.

        return _local_process

    def start_process(self):
        # TODO: add null exception check for _process
        self._process.start()

    def stop_process(self):
        # TODO: add null exception check for _process

        try:
            self._process.stop()
        except Exception as e:
            # TODO: Change roslaunch to raise exception
            rospy.logdebug('Proxy stop_process exception={}'.format(e.message))

    def get_spawn_count(self):
        return self._process.spawn_count

    def get_proc_name(self):
        return self._process.name

    def get_proc_exit_code(self):
        return self._process.exit_code