Can not get latency stats

[dgalan-xxia]

Version information
snappi-ixnetwork 0.7.5

Describe the bug
Below snippet seems to have no effect in this version:

print("Enabling latency metrics")
for flow in config.flows:
    flow.metrics.latency.enable = True

Since below returns None

results = api.get_metrics(request).flow_metrics
latencies = [res.latency.average_ns for res in results ]

[alakendu]

I am getting this latency when run our internal UT (https://github.com/open-traffic-generator/snappi-ixnetwork/blob/main/tests/metrics/test_latency_metrics.py) with api._enable_flow_tracking(True)

  latency:
    average_ns: 0
    maximum_ns: 0
    minimum_ns: 0

It looks like this is specific to some HW or test script. Could you please provide entire script and chassis/ card type

[dgalan-xxia]

Indeed - our script creates flows and enables latency twice on the same session.
Our code had a check to determine if it's running on UHD and enable latency only if not. That check was to see if href of a chassis object is populated, which now, after the first apply, it is, causing the latency enabling to be skipped for the second round of flows. Fixing our scripts.

[dgalan-xxia]

did some more testing and realized our script was clearing the config (applying an empty config) before checking the chassis properties. so the issue seems to be that clearing the config does not clear the chassis/location object anymore

    def enable_latency_stats(traffic_api: snappi.Api, config:snappi.snappi.Config):
        # if setup is not UHD, enable latency stats
        traffic_api.set_config(traffic_api.config())
        ixn_session = traffic_api.assistant.Session.Ixnetwork
        chassis = ixn_session.AvailableHardware.Chassis.find()
        try:
            chassis.href #only UHD has an empty session prepopulated with a chassis
        except:
            print("Enabling latency metrics")
            for flow in config.flows:
                flow.metrics.latency.enable = True