7.2. Threading model¶

Operations on the same Connector instance or any contained Input or Output are, in general, not protected for multi-threaded access. The only exceptions are the following wait operations.

Thread-safe operations:

Connector.wait() (wait for data on any Input)
Output.wait() (wait for acknowledgments)
Output.wait_for_subscriptions()
Input.wait() (wait for data on this Input)
Input.wait_for_publications()

These operations can block a thread while the same Connector is used in a different thread.

Note

Currently Input.wait() and Input.wait_for_publications() cannot both be called at the same time on the same Input instance.

Note

Output.write() can block the current thread under certain circumstances, but Output.write() is not thread-safe.

All operations on different Connector instances are thread-safe.

Applications can implement their own thread-safety mechanism around a Connector instance. The following section provides an example.

7.2.1. Protecting calls to Connector¶

This example shows how to use the Python threading package to protect calls to the same Connector:

import threading

connector = rti.Connector("MyParticipantLibrary::MyParticipant", "ShapeExample.xml")
lock = threading.RLock()

def read_thread():
   with lock: # Protect access to methods on the same Connector
      input = connector.get_input("MySubscriber::MySquareReader")

   input.wait() # wait outside the lock

   with lock: # Take the lock again
      input.take();
      for sample in input.samples.valid_data_iter:
         print(sample.get_dictionary())

def write_thread():
   with lock: # Protect access to methods on the same Connector
      output = connector.get_output("MyPublisher::MySquareWriter")
      output.instance['x'] = 10
      output.write()

# Spawn read_thread and write_thread...