fix(powermetrics): report 0 W when powermetrics returns no samples

codecarbon/core/powermetrics.py

@@ -112,6 +112,7 @@ def __init__(
         self._system = sys.platform.lower()
         self._n_points = n_points
         self._interval = interval
+        self._warned_missing_samples = set()
         self._setup_cli()
 
     def _setup_cli(self) -> None:
@@ -175,29 +176,27 @@ def get_details(self) -> Dict:
         try:
             with open(self._log_file_path) as f:
                 logfile = f.read()
-            cpu_pattern = r"CPU Power: (\d+) mW"
-            cpu_power_list = re.findall(cpu_pattern, logfile)
-
-            details["CPU Power"] = np.mean(
-                [float(power) / 1000 for power in cpu_power_list]
-            )
-            details["CPU Energy Delta"] = np.sum(
-                [
-                    (self._interval / 1000) * (float(power) / 1000)
-                    for power in cpu_power_list
-                ]
-            )
-            gpu_pattern = r"GPU Power: (\d+) mW"
-            gpu_power_list = re.findall(gpu_pattern, logfile)
-            details["GPU Power"] = np.mean(
-                [float(power) / 1000 for power in gpu_power_list]
-            )
-            details["GPU Energy Delta"] = np.sum(
-                [
-                    (self._interval / 1000) * (float(power) / 1000)
-                    for power in gpu_power_list
-                ]
-            )
+            for chip_part in ("CPU", "GPU"):
+                power_list = re.findall(rf"{chip_part} Power: (\d+) mW", logfile)
+                if not power_list:
+                    # np.mean([]) is NaN, and NaN poisons every downstream total,
+                    # so report 0 W instead and make the situation visible.
+                    # get_details() runs every measurement cycle, so warn only
+                    # once per chip part to avoid flooding the log.
+                    if chip_part not in self._warned_missing_samples:
+                        self._warned_missing_samples.add(chip_part)
+                        logger.warning(
+                            f"Powermetrics returned no '{chip_part} Power' sample in "
+                            + f"{self._log_file_path}, reporting 0 W (warned once)."
+                        )
+                    details[f"{chip_part} Power"] = 0.0
+                    details[f"{chip_part} Energy Delta"] = 0.0
+                    continue
+                watts = [float(power) / 1000 for power in power_list]
+                details[f"{chip_part} Power"] = np.mean(watts)
+                details[f"{chip_part} Energy Delta"] = np.sum(
+                    [(self._interval / 1000) * watt for watt in watts]
+                )
         except Exception as e:
             logger.info(
                 f"Unable to read Powermetrics logged file at {self._log_file_path}\n \

tests/test_powermetrics.py

@@ -73,6 +73,59 @@ def test_get_details(self, mock_setup, mock_log_values):
 
         assert cpu_details == expected_details
 
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._log_values")
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._setup_cli")
+    def test_get_details_without_samples(self, mock_setup, mock_log_values, tmp_path):
+        """An empty log must report 0 W, not NaN, which would poison all totals."""
+        (tmp_path / "empty_powermetrics_log.txt").write_text("")
+        powermetrics = ApplePowermetrics(
+            output_dir=str(tmp_path),
+            log_file_name="empty_powermetrics_log.txt",
+        )
+
+        assert powermetrics.get_details() == {
+            "CPU Power": 0.0,
+            "CPU Energy Delta": 0.0,
+            "GPU Power": 0.0,
+            "GPU Energy Delta": 0.0,
+        }
+
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._log_values")
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._setup_cli")
+    def test_get_details_without_gpu_samples(
+        self, mock_setup, mock_log_values, tmp_path
+    ):
+        """A log with no GPU line must report 0 W for the GPU, not NaN."""
+        (tmp_path / "cpu_only_log.txt").write_text("CPU Power: 500 mW\n")
+        powermetrics = ApplePowermetrics(
+            output_dir=str(tmp_path),
+            log_file_name="cpu_only_log.txt",
+        )
+
+        details = powermetrics.get_details()
+
+        assert details["CPU Power"] == 0.5
+        assert details["GPU Power"] == 0.0
+        assert details["GPU Energy Delta"] == 0.0
+
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._log_values")
+    @mock.patch("codecarbon.core.powermetrics.ApplePowermetrics._setup_cli")
+    def test_missing_samples_warns_only_once(
+        self, mock_setup, mock_log_values, tmp_path
+    ):
+        """get_details() runs every cycle, so the warning must not flood the log."""
+        (tmp_path / "cpu_only_log.txt").write_text("CPU Power: 500 mW\n")
+        powermetrics = ApplePowermetrics(
+            output_dir=str(tmp_path),
+            log_file_name="cpu_only_log.txt",
+        )
+
+        with mock.patch("codecarbon.core.powermetrics.logger.warning") as mock_warning:
+            for _ in range(3):
+                assert powermetrics.get_details()["GPU Power"] == 0.0
+
+        mock_warning.assert_called_once()
+
     def test_is_powermetrics_available_returns_false_on_instantiation_error(self):
         from codecarbon.core.powermetrics import clear_powermetrics_cache