dprint doesn't need to be a ctxman

replacer.py

@@ -14,7 +14,7 @@ import contextvars
 from yarl import URL
 from aiohttp import web
 import pytomlpp as toml
-from utils import build_dprint, ContextVar
+from utils import build_dprint_factory, ContextVar
 
 def load_config():
 	with open(sys.argv[1] if len(sys.argv) > 1 else 'config.toml') as f:
@@ -32,12 +32,13 @@ def load_config():
 	return config
 
 config = load_config()
-dprint = build_dprint(config.get('debug'))
+dprint = build_dprint_factory(config.get('debug'))
 http = ContextVar('http')
 
 async def handler(request):
 	hconfig = config['hosts'][request.host]
-	async with dprint() as print, http().request(
+	print = dprint()
+	async with http().request(
 		request.method,
 		# TODO support upstream unix sockets
 		URL(hconfig['upstream']).with_path(request.path),

utils.py

@@ -2,7 +2,6 @@
 
 import random
 import asyncio
-import contextlib
 import contextvars
 from aiohttp import web
 
@@ -17,23 +16,18 @@ class ContextVar:
 	def set(self, *args): return self._var.set(*args)
 	def reset(self, *args): return self._var.reset(*args)
 
-class asyncnullcontext(contextlib.AbstractAsyncContextManager):
-	async def __aenter__(self): return None
-	async def __aexit__(self, *excinfo): return None
-
-def build_dprint(debug: bool):
+def build_dprint_factory(debug: bool):
 	if debug:
-		class dprint(asyncnullcontext):
+		def dprint_factory():
 			# 8 byte pseudo-random request tag
-			def __init__(self): self.req_id = ''.join(random.choices('0123456789abcdef', k=8 * 2))
-			def print(self, *args, **kwargs): print(f'[{self.req_id}]', *args, **kwargs)
-			async def __aenter__(self): return self.print
+			req_id = ''.join(random.choices('0123456789abcdef', k=8 * 2))
+			def dprint(*args, **kwargs): print(f'[{req_id}]', *args, **kwargs)
+			return dprint
 	else:
-		class dprint(asyncnullcontext):
-			async def __aenter__(self):
-				return lambda *args, **kwargs: None
+		def dprint(*args, **kwargs): return None
+		def dprint_factory(): return dprint
 
-	return dprint
+	return dprint_factory
 
 def make_unlimited_request(*args):
 	return web.BaseRequest(*args, loop=asyncio.get_running_loop(), client_max_size=None)