Waitset Use Cases

Using wait-sets and conditions. More...

Using wait-sets and conditions.

Setting up a wait-set

• Create a wait-set

  WaitSet waitset = new WaitSet();

• Attach conditions

  Condition cond1 = entity.get_statuscondition();
  Condition cond2 = reader.create_readcondition(
  SampleStateKind.NOT_READ_SAMPLE_STATE,
      ViewStateKind.ANY_VIEW_STATE,
      InstanceStateKind.ANY_INSTANCE_STATE);
  Condition cond3 = new GuardCondition();
  
  try {
      waitset.attach_condition(cond1);
      waitset.attach_condition(cond2);
      waitset.attach_condition(cond3);
  } catch (DDS.Exception) {
      // ... error
  }

Waiting for condition(s) to trigger

• Set up a wait-set
• Wait for a condition to trigger or timeout, whichever occurs first

  Duration_t timeout;
  timeout.sec = 0;
  timeout.nanosec = 1000000; // 1ms
  
  // holder for active conditions
  ConditionSeq active_conditions = new ConditionSeq();
  
  bool is_cond1_triggered = false;
  bool is_cond2_triggered = false;
  
  try {
      waitset.wait(active_conditions, timeout);
  
      // check if "cond1" or "cond2" are triggered:
      for (int i = 0; i < active_conditions.length; ++i) {
          if (active_conditions.get_at(i) == cond1) {
               Console.WriteLine("Cond1 was triggered!");
               is_cond1_triggered = true;       
          }
          if (active_conditions.get_at(i) == cond2) {
              Console.WriteLine("Cond2 was triggered!");
              is_cond2_triggered = true;        
          }
      }
  
      if (is_cond1_triggered) {
          // ... do something because "cond1" was triggered ...
      }
  
      if (is_cond2_triggered) {
          // ... do something because "cond2" was triggered ...
      }
  } catch (DDS.Retcode_Timeout) {
      // timeout!
      Console.WriteLine(
          "Wait timed out!! None of the conditions was triggered.");
  } catch (DDS.Exception) {
      // ... check for cause of failure
      throw;
  }

Tearing down a wait-set

• Delete the wait-set

  waitset.Dispose();
  waitset = null;