Add an optional timeout_sec input to Client.call() to fix issue https://github.com/ros2/rclpy/issues/1181

rclpy/rclpy/client.py

@@ -69,14 +69,19 @@ def __init__(
 
         self._lock = threading.Lock()
 
-    def call(self, request: SrvTypeRequest) -> SrvTypeResponse:
+    def call(
+        self,
+        request: SrvTypeRequest,
+        timeout_sec: Optional[float] = None
+    ) -> Optional[SrvTypeResponse]:
         """
         Make a service request and wait for the result.
 
-        .. warning:: Do not call this method in a callback or a deadlock may occur.
+        .. warning:: Do not call this method in a callback, or a deadlock or timeout may occur.
 
         :param request: The service request.
-        :return: The service response.
+        :param timeout_sec: Seconds to wait. If ``None``, then wait forever.
+        :return: The service response, or None if timed out.
         :raises: TypeError if the type of the passed request isn't an instance
           of the Request type of the provided service when the client was
           constructed.
@@ -97,7 +102,9 @@ def unblock(future):
         # The callback might have been added after the future is completed,
         # resulting in the event never being set.
         if not future.done():
-            event.wait()
+            if not event.wait(timeout_sec):
+                # Timed out. remove_pending_request() to free resources
+                self.remove_pending_request(future)
         if future.exception() is not None:
             raise future.exception()
         return future.result()

rclpy/test/test_client.py

@@ -13,12 +13,15 @@
 # limitations under the License.
 
 import platform
+import threading
 import time
+import traceback
 import unittest
 
 from rcl_interfaces.srv import GetParameters
 import rclpy
 import rclpy.executors
+import rclpy.node
 from rclpy.utilities import get_rmw_implementation_identifier
 from test_msgs.srv import Empty
 
@@ -56,6 +59,21 @@ def do_test_service_name(cls, test_service_name_list):
             client.destroy()
             node.destroy_node()
 
+    @staticmethod
+    def _spin_rclpy_node(
+        rclpy_node: rclpy.node.Node,
+        rclpy_executor: rclpy.executors.SingleThreadedExecutor
+    ) -> None:
+        try:
+            rclpy_executor.spin()
+        except rclpy.executors.ExternalShutdownException:
+            pass
+        except Exception as err:
+            traceback.print_exc()
+            print(rclpy_node.get_name() + ': ' + str(err))
+        print(rclpy_node.get_name() + ': rclpy_node exit')
+#        rclpy_node.destroy_node()
+
     def test_wait_for_service_5sec(self):
         cli = self.node.create_client(GetParameters, 'get/parameters')
         try:
@@ -183,6 +201,47 @@ def test_get_service_name_after_remapping(self):
         ]
         TestClient.do_test_service_name(test_service_name_list)
 
+    def test_sync_call(self):
+        def _service(request, response):
+            return response
+        cli = self.node.create_client(GetParameters, 'get/parameters')
+        srv = self.node.create_service(GetParameters, 'get/parameters', _service)
+        try:
+            self.assertTrue(cli.wait_for_service(timeout_sec=20))
+            executor = rclpy.executors.SingleThreadedExecutor(context=self.context)
+            executor.add_node(self.node)
+            executor_thread = threading.Thread(
+                target=TestClient._spin_rclpy_node, args=(self.node, executor))
+            executor_thread.start()
+            result = cli.call(GetParameters.Request(), 0.5)
+            self.assertTrue(result is not None)
+            executor.shutdown()
+            executor_thread.join()
+        finally:
+            self.node.destroy_client(cli)
+            self.node.destroy_service(srv)
+
+    def test_sync_call_timeout(self):
+        def _service(request, response):
+            time.sleep(1)
+            return response
+        cli = self.node.create_client(GetParameters, 'get/parameters')
+        srv = self.node.create_service(GetParameters, 'get/parameters', _service)
+        try:
+            self.assertTrue(cli.wait_for_service(timeout_sec=20))
+            executor = rclpy.executors.SingleThreadedExecutor(context=self.context)
+            executor.add_node(self.node)
+            executor_thread = threading.Thread(
+                target=TestClient._spin_rclpy_node, args=(self.node, executor))
+            executor_thread.start()
+            result = cli.call(GetParameters.Request(), 0.5)
+            self.assertTrue(result is None)
+            executor.shutdown()
+            executor_thread.join()
+        finally:
+            self.node.destroy_client(cli)
+            self.node.destroy_service(srv)
+
 
 if __name__ == '__main__':
     unittest.main()