Asynchronous client calls in a timer cause the timer to never execute…

… a second time

  ros2/rclpy#1018

Signed-off-by: Tomoya Fujita <[email protected]>

prover_rclpy/setup.py

@@ -54,6 +54,8 @@
             'rclpy_1000_sub = src.rclpy_1000_sub:main',
             'rclpy_1016_service = src.rclpy_1016_service:main',
             'rclpy_1016_client = src.rclpy_1016_client:main',
+            'rclpy_1018_server = src.rclpy_1018_server:main',
+            'rclpy_1018_client = src.rclpy_1018_client:main',
             'rclpy_doctor_940 = src.rclpy_doctor_940:main',
             'rclpy_foo_940 = src.rclpy_foo_940:main',
             'rclpy_bar_940 = src.rclpy_bar_940:main',

prover_rclpy/src/rclpy_1018_client.py

@@ -0,0 +1,69 @@
+from example_interfaces.srv import AddTwoInts
+import rclpy
+from rclpy.node import Node
+
+from rclpy.executors import MultiThreadedExecutor
+from rclpy.callback_groups import MutuallyExclusiveCallbackGroup
+
+
+class MinimalClient(Node):
+    def __init__(self):
+        super().__init__("minimal_client_async")
+        self.cb = None
+        self.timer_cb = MutuallyExclusiveCallbackGroup()
+        self.cli = self.create_client(
+            AddTwoInts, "add_two_ints", callback_group=self.cb
+        )
+        while not self.cli.wait_for_service(timeout_sec=1.0):
+            self.get_logger().info("service not available, waiting again...")
+        self.req = AddTwoInts.Request()
+
+        # Create a timer for the main loop execution
+        self.timer = self.create_timer(
+            1.0, self.main_loop, callback_group=self.timer_cb
+        )
+
+    async def send_request(self, a, b):
+        self.get_logger().info("send_request: enter")
+        self.req.a = a
+        self.req.b = b
+
+        # Only works once, then never executes the timer again
+        #self.future = self.cli.call_async(self.req)
+        #rclpy.spin_until_future_complete(self, self.future)
+        #self.get_logger().info("send_request: exit")
+        #return self.future.result()
+
+        # Suggested example by @llapx
+        #self.future = self.cli.call_async(self.req)
+        #while rclpy.ok():
+        #    if self.future.done() and self.future.result():
+        #        self.get_logger().info("send_request: exit")
+        #        return self.future.result()
+
+        return await self.cli.call_async(self.req)
+
+        # Used to work, but blocks now
+        # return self.cli.call(self.req)
+
+    async def main_loop(self) -> None:
+        response = await self.send_request(4, 2)
+        self.get_logger().info(
+            "Result of add_two_ints: for %d + %d = %d" % (4, 2, response.sum)
+        )
+
+
+def main(args=None):
+    rclpy.init(args=args)
+
+    minimal_client = MinimalClient()
+
+    executor = MultiThreadedExecutor()
+    executor.add_node(minimal_client)
+    executor.spin()
+
+    rclpy.shutdown()
+
+
+if __name__ == "__main__":
+    main()

prover_rclpy/src/rclpy_1018_server.py

@@ -0,0 +1,31 @@
+from example_interfaces.srv import AddTwoInts
+
+import rclpy
+from rclpy.node import Node
+
+
+class MinimalService(Node):
+
+    def __init__(self):
+        super().__init__('minimal_service')
+        self.srv = self.create_service(AddTwoInts, 'add_two_ints', self.add_two_ints_callback)
+
+    def add_two_ints_callback(self, request, response):
+        response.sum = request.a + request.b
+        self.get_logger().info('Incoming request\na: %d b: %d' % (request.a, request.b))
+
+        return response
+
+
+def main(args=None):
+    rclpy.init(args=args)
+
+    minimal_service = MinimalService()
+
+    rclpy.spin(minimal_service)
+
+    rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()