def __init__(self):
'''
Creates a new instance. Find the topic of the master_discovery node using
U{fkie_master_discovery.interface_finder.get_changes_topic()
<http://docs.ros.org/api/fkie_master_discovery/html/modules.html#interface-finder-module>}.
Also the parameter C{~ignore_hosts} will be analyzed to exclude hosts from sync.
'''
self.masters = {}
# the connection to the local service master
self.materuri = masteruri_from_master()
'''@ivar: the ROS master URI of the C{local} ROS master. '''
self.__lock = threading.RLock()
# load interface
self._load_interface()
# subscribe to changes notifier topics
topic_names = interface_finder.get_changes_topic(
masteruri_from_master())
self.sub_changes = dict()
'''@ivar: `dict` with topics {name: U{rospy.Subscriber<http://docs.ros.org/api/rospy/html/rospy.topics.Subscriber-class.html>}} publishes the changes of the discovered ROS masters.'''
for topic_name in topic_names:
rospy.loginfo("listen for updates on %s", topic_name)
self.sub_changes[topic_name] = rospy.Subscriber(
topic_name, MasterState, self._rosmsg_callback_master_state)
self.__timestamp_local = None
self.__own_state = None
self.update_timer = None
self.own_state_getter = None
self._join_threads = dict(
) # threads waiting for stopping the sync thread
# initialize the ROS services
rospy.Service('~get_sync_info', GetSyncInfo,
self._rosservice_get_sync_info)
rospy.on_shutdown(self.finish)
self.obtain_masters()
def registerByROS(self, masteruri, wait=False):
'''
This method creates a ROS subscriber to received the notifications of ROS
master updates. The retrieved messages will be emitted as state_signal.
@param masteruri: the ROS master URI
@type masteruri: C{str}
@param wait: wait for the topic
@type wait: C{boolean}
@return: the topic name or an empty string
'''
result = ''
topic_names = interface_finder.get_changes_topic(masteruri, wait)
self.stop()
if not hasattr(self, 'sub_changes'):
self.sub_changes = []
self.sub_names = []
if set(self.sub_names) != set(topic_names):
self.stop()
self.sub_changes = []
for topic_name in topic_names:
rospy.loginfo("listen for updates on %s", topic_name)
sub_changes = rospy.Subscriber(topic_name, MasterState, self.handlerMasterStateMsg)
self.sub_changes.append(sub_changes)
result = topic_name
self.sub_names = topic_names
return result