process replay: prefix setup in helper (#24636)

* prefix setup in helper

* context manager

* name change + none default

* skip checking prefix

* type hints + unset env

selfdrive/test/process_replay/helpers.py

@@ -0,0 +1,26 @@
+import os
+import shutil
+import uuid
+
+from common.params import Params
+
+class OpenpilotPrefix(object):
+  def __init__(self, prefix: str = None) -> None:
+    self.prefix = prefix if prefix else str(uuid.uuid4())
+    self.msgq_path = os.path.join('/dev/shm', self.prefix)
+
+  def __enter__(self):
+    os.environ['OPENPILOT_PREFIX'] = self.prefix
+    try:
+      os.mkdir(self.msgq_path)
+    except FileExistsError:
+      pass
+
+  def __exit__(self, exc_type, exc_obj, exc_tb):
+    symlink_path = Params().get_param_path()
+    if os.path.exists(symlink_path):
+      shutil.rmtree(os.path.realpath(symlink_path), ignore_errors=True)
+      os.remove(symlink_path)
+    shutil.rmtree(self.msgq_path, ignore_errors=True)
+    del os.environ['OPENPILOT_PREFIX']
+    return True

selfdrive/test/process_replay/process_replay.py

@@ -4,9 +4,7 @@ import os
 import sys
 import threading
 import time
-import shutil
 import signal
-import uuid
 from collections import namedtuple
 
 import capnp
@@ -18,6 +16,7 @@ from common.params import Params
 from common.timeout import Timeout
 from selfdrive.car.fingerprints import FW_VERSIONS
 from selfdrive.car.car_helpers import get_car, interfaces
+from selfdrive.test.process_replay.helpers import OpenpilotPrefix
 from selfdrive.manager.process import PythonProcess
 from selfdrive.manager.process_config import managed_processes
 
@@ -337,35 +336,13 @@ CONFIGS = [
   ),
 ]
 
-def setup_prefix():
-  os.environ['OPENPILOT_PREFIX'] = str(uuid.uuid4())
-  msgq_path = os.path.join('/dev/shm', os.environ['OPENPILOT_PREFIX'])
-  try:
-    os.mkdir(msgq_path)
-  except FileExistsError:
-    pass
-
-
-def teardown_prefix():
-  if not os.environ.get("OPENPILOT_PREFIX", 0):
-    return
-  symlink_path = Params().get_param_path()
-  if os.path.exists(symlink_path):
-    shutil.rmtree(os.path.realpath(symlink_path), ignore_errors=True)
-    os.remove(symlink_path)
-  msgq_path = os.path.join('/dev/shm', os.environ['OPENPILOT_PREFIX'])
-  shutil.rmtree(msgq_path, ignore_errors=True)
-
 
 def replay_process(cfg, lr, fingerprint=None):
-  setup_prefix()
-  try:
+  with OpenpilotPrefix():
     if cfg.fake_pubsubmaster:
       return python_replay_process(cfg, lr, fingerprint)
     else:
       return cpp_replay_process(cfg, lr, fingerprint)
-  finally:
-    teardown_prefix()
 
 def setup_env(simulation=False):
   params = Params()