URLFile: add typing and internalize pool manager (#31466)

* URLFile: add typing and internalize pool manager

* cleanup

tools/lib/url_file.py

@@ -4,6 +4,7 @@ import socket
 import time
 from hashlib import sha256
 from urllib3 import PoolManager, Retry
+from urllib3.response import BaseHTTPResponse
 from urllib3.util import Timeout
 
 from openpilot.common.file_helpers import atomic_write_in_dir
@@ -14,7 +15,7 @@ CHUNK_SIZE = 1000 * K
 
 logging.getLogger("urllib3").setLevel(logging.WARNING)
 
-def hash_256(link):
+def hash_256(link: str) -> str:
   hsh = str(sha256((link.split("?")[0]).encode('utf-8')).hexdigest())
   return hsh
 
@@ -23,26 +24,26 @@ class URLFileException(Exception):
   pass
 
 
-def new_pool_manager() -> PoolManager:
-  socket_options = [(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),]
-  retries = Retry(total=5, backoff_factor=0.5, status_forcelist=[409, 429, 503, 504])
-  return PoolManager(num_pools=10, maxsize=100, socket_options=socket_options, retries=retries)
-
-
-def set_pool_manager():
-  URLFile._pool_manager = new_pool_manager()
-os.register_at_fork(after_in_child=set_pool_manager)
+class URLFile:
+  _pool_manager: PoolManager|None = None
 
+  @staticmethod
+  def reset() -> None:
+    URLFile._pool_manager = None
 
-class URLFile:
-  _pool_manager = new_pool_manager()
+  @staticmethod
+  def pool_manager() -> PoolManager:
+    if URLFile._pool_manager is None:
+      socket_options = [(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),]
+      retries = Retry(total=5, backoff_factor=0.5, status_forcelist=[409, 429, 503, 504])
+      URLFile._pool_manager = PoolManager(num_pools=10, maxsize=100, socket_options=socket_options, retries=retries)
+    return URLFile._pool_manager
 
-  def __init__(self, url, timeout=10, debug=False, cache=None):
+  def __init__(self, url: str, timeout: int=10, debug: bool=False, cache: bool|None=None):
     self._url = url
     self._timeout = Timeout(connect=timeout, read=timeout)
     self._pos = 0
-    self._length = None
-    self._local_file = None
+    self._length: int|None = None
     self._debug = debug
     #  True by default, false if FILEREADER_CACHE is defined, but can be overwritten by the cache input
     self._force_download = not int(os.environ.get("FILEREADER_CACHE", "0"))
@@ -55,23 +56,20 @@ class URLFile:
   def __enter__(self):
     return self
 
-  def __exit__(self, exc_type, exc_value, traceback):
-    if self._local_file is not None:
-      os.remove(self._local_file.name)
-      self._local_file.close()
-      self._local_file = None
+  def __exit__(self, exc_type, exc_value, traceback) -> None:
+    pass
 
-  def _request(self, method, url, headers=None):
-    return URLFile._pool_manager.request(method, url, timeout=self._timeout, headers=headers)
+  def _request(self, method: str, url: str, headers: dict[str, str]|None=None) -> BaseHTTPResponse:
+    return URLFile.pool_manager().request(method, url, timeout=self._timeout, headers=headers)
 
-  def get_length_online(self):
+  def get_length_online(self) -> int:
     response = self._request('HEAD', self._url)
     if not (200 <= response.status <= 299):
       return -1
     length = response.headers.get('content-length', 0)
     return int(length)
 
-  def get_length(self):
+  def get_length(self) -> int:
     if self._length is not None:
       return self._length
 
@@ -88,7 +86,7 @@ class URLFile:
         file_length.write(str(self._length))
     return self._length
 
-  def read(self, ll=None):
+  def read(self, ll: int|None=None) -> bytes:
     if self._force_download:
       return self.read_aux(ll=ll)
 
@@ -120,7 +118,7 @@ class URLFile:
         self._pos = file_end
         return response
 
-  def read_aux(self, ll=None):
+  def read_aux(self, ll: int|None=None) -> bytes:
     download_range = False
     headers = {}
     if self._pos != 0 or ll is not None:
@@ -155,9 +153,12 @@ class URLFile:
     self._pos += len(ret)
     return ret
 
-  def seek(self, pos):
+  def seek(self, pos:int) -> None:
     self._pos = pos
 
   @property
-  def name(self):
+  def name(self) -> str:
     return self._url
+
+
+os.register_at_fork(after_in_child=URLFile.reset)