test_snapshot_ab: open code sample_latency

This function only has one possible call-site, and that's
test_restore_latency. Inlining it into its call site makes things a bit
simpler (no need for a temporary array).

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/integration_tests/performance/test_snapshot_ab.py

@@ -4,7 +4,6 @@
 import tempfile
 from dataclasses import dataclass
 from functools import lru_cache
-from typing import List
 
 import pytest
 
@@ -83,25 +82,6 @@ def configure_vm(self, microvm_factory, guest_kernel, rootfs, metrics) -> Microv
 
         return vm
 
-    def sample_latency(self, microvm_factory, snapshot) -> List[float]:
-        """Collects latency samples for the microvm configuration specified by this instance"""
-        values = []
-
-        for microvm in microvm_factory.build_n_from_snapshot(snapshot, ITERATIONS):
-            value = 0
-            # Parse all metric data points in search of load_snapshot time.
-            microvm.flush_metrics()
-            metrics = microvm.get_all_metrics()
-            for data_point in metrics:
-                cur_value = data_point["latencies_us"]["load_snapshot"]
-                if cur_value > 0:
-                    value = cur_value / USEC_IN_MSEC
-                    break
-            assert value > 0
-            values.append(value)
-
-        return values
-
 
 @pytest.mark.nonci
 @pytest.mark.parametrize(
@@ -136,10 +116,14 @@ def test_restore_latency(
     snapshot = vm.snapshot_full()
     vm.kill()
 
-    samples = test_setup.sample_latency(
-        microvm_factory,
-        snapshot,
-    )
-
-    for sample in samples:
-        metrics.put_metric("latency", sample, "Milliseconds")
+    for microvm in microvm_factory.build_n_from_snapshot(snapshot, ITERATIONS):
+        value = 0
+        # Parse all metric data points in search of load_snapshot time.
+        microvm.flush_metrics()
+        for data_point in microvm.get_all_metrics():
+            cur_value = data_point["latencies_us"]["load_snapshot"]
+            if cur_value > 0:
+                value = cur_value / USEC_IN_MSEC
+                break
+        assert value > 0
+        metrics.put_metric("latency", value, "Milliseconds")