Waitset Use Cases
[Programming How-To's]

Using wait-sets and conditions. More...

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;