Cleaning up and improving Cgroup methods

mir-ci/mir_ci/cgroups.py

@@ -29,20 +29,16 @@ def get_cgroup_dir(pid: int) -> pathlib.Path:
 
     @staticmethod
     def _get_cgroup_dir_internal(pid: int) -> pathlib.Path:
-        path = None
         cgroup_file = f"/proc/{pid}/cgroup"
 
         with open(cgroup_file, "r") as group_file:
-            lines = group_file.readlines()
-            for line in lines:
+            for line in group_file.readlines():
                 if not line.startswith("0::"):
                     continue
 
-                path = pathlib.Path(f"/sys/fs/cgroup/{line[3:]}".strip())
+                return pathlib.Path(f"/sys/fs/cgroup/{line[3:]}".strip())
 
-        if not path:
-            raise RuntimeError(f"Unable to find path for process with pid: {pid}")
-        return path
+        raise RuntimeError(f"Unable to find path for process with pid: {pid}")
 
     def _read_file(self, file_name: str) -> Iterator[str]:
         if not self.path:
@@ -58,16 +54,16 @@ def get_cpu_time_microseconds(self) -> int:
             if split_line[0] == "usage_usec":
                 return int(split_line[1])
 
-        return 0
+        raise RuntimeError(f"Unable to get the cpu time for cgroup with pid: {self.pid}")
 
     def get_current_memory(self) -> int:
         for line in self._read_file("memory.current"):
             return int(line)
 
-        return 0
+        raise RuntimeError(f"Unable to get the current memory for cgroup with pid: {self.pid}")
 
     def get_peak_memory(self) -> int:
         for line in self._read_file("memory.peak"):
             return int(line)
 
-        return 0
+        raise RuntimeError(f"Unable to get the peak memory for cgroup with pid: {self.pid}")