proxy_action_client.py

Go to the documentation of this file.

#!/usr/bin/env python
import rospy
import actionlib
from threading import Timer

from flexbe_core.logger import Logger


class ProxyActionClient(object):
    """
    A proxy for calling actions.
    """
    _clients = {}

    _result = {}
    _feedback = {}

    def __init__(self, topics={}, wait_duration=10):
        """
        Initializes the proxy with optionally a given set of clients.

        @type topics: dictionary string - message class
        @param topics: A dictionay containing a collection of topic - message type pairs.

        @type wait_duration: int
        @param wait_duration: Defines how long to wait for each client in the
            given set to become available (if it is not already available).
        """
        for topic, msg_type in topics.items():
            self.setupClient(topic, msg_type, wait_duration)

    def setupClient(self, topic, msg_type, wait_duration=10):
        """
        Tries to set up an action client for calling it later.

        @type topic: string
        @param topic: The topic of the action to call.

        @type msg_type: msg type
        @param msg_type: The type of messages of this action client.

        @type wait_duration: int
        @param wait_duration: Defines how long to wait for the given client if it is not available right now.
        """
        if topic not in ProxyActionClient._clients:
            ProxyActionClient._clients[topic] = actionlib.SimpleActionClient(topic, msg_type)
            self._check_topic_available(topic, wait_duration)

    def send_goal(self, topic, goal):
        """
        Performs an action call on the given topic.

        @type topic: string
        @param topic: The topic to call.

        @type goal: action goal
        @param goal: The request to send to the action server.
        """
        if not self._check_topic_available(topic):
            raise ValueError('Cannot send goal for action client %s: Topic not available.' % topic)
        # reset previous results
        ProxyActionClient._result[topic] = None
        ProxyActionClient._feedback[topic] = None
        # send goal
        ProxyActionClient._clients[topic].send_goal(
            goal,
            done_cb=lambda ts, r: self._done_callback(topic, ts, r),
            feedback_cb=lambda f: self._feedback_callback(topic, f)
        )

    def _done_callback(self, topic, terminal_state, result):
        ProxyActionClient._result[topic] = result

    def _feedback_callback(self, topic, feedback):
        ProxyActionClient._feedback[topic] = feedback

    def is_available(self, topic):
        """
        Checks if the client on the given action topic is available.

        @type topic: string
        @param topic: The topic of interest.
        """
        return self._check_topic_available(topic)

    def has_result(self, topic):
        """
        Checks if the given action call already has a result.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._result.get(topic) is not None

    def get_result(self, topic):
        """
        Returns the result message of the given action call.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._result.get(topic)

    def remove_result(self, topic):
        """
        Removes the latest result message of the given action call.

        @type topic: string
        @param topic: The topic of interest.
        """
        ProxyActionClient._result[topic] = None

    def has_feedback(self, topic):
        """
        Checks if the given action call has any feedback.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._feedback.get(topic) is not None

    def get_feedback(self, topic):
        """
        Returns the latest feedback message of the given action call.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._feedback.get(topic)

    def remove_feedback(self, topic):
        """
        Removes the latest feedback message of the given action call.

        @type topic: string
        @param topic: The topic of interest.
        """
        ProxyActionClient._feedback[topic] = None

    def get_state(self, topic):
        """
        Determines the current actionlib state of the given action topic.
        A list of possible states is defined in actionlib_msgs/GoalStatus.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._clients[topic].get_state()

    def is_active(self, topic):
        """
        Determines if an action request is already being processed on the given topic.

        @type topic: string
        @param topic: The topic of interest.
        """
        return ProxyActionClient._clients[topic].simple_state != actionlib.SimpleGoalState.DONE

    def cancel(self, topic):
        """
        Cancels the current action call on the given action topic.

        @type topic: string
        @param topic: The topic of interest.
        """
        ProxyActionClient._clients[topic].cancel_goal()

    def _check_topic_available(self, topic, wait_duration=1):
        """
        Checks whether a topic is available.

        @type topic: string
        @param topic: The topic of the action.

        @type wait_duration: int
        @param wait_duration: Defines how long to wait for the given client if it is not available right now.
        """
        client = ProxyActionClient._clients.get(topic)
        if client is None:
            Logger.logerr("Action client %s not yet registered, need to add it first!" % topic)
            return False
        t = Timer(.5, self._print_wait_warning, [topic])
        t.start()
        available = client.wait_for_server(rospy.Duration.from_sec(wait_duration))
        warning_sent = False
        try:
            t.cancel()
        except Exception:
            # already printed the warning
            warning_sent = True

        if not available:
            Logger.logerr("Action client %s timed out!" % topic)
            return False
        else:
            if warning_sent:
                Logger.loginfo("Finally found action client %s..." % (topic))
        return True

    def _print_wait_warning(self, topic):
        Logger.logwarn("Waiting for action client %s..." % (topic))