fix: improve async validator handling in Pubsub class (#705)

Signed-off-by: varun-r-mallya <varunrmallya@gmail.com>

Author: varun-r-mallya

libp2p/pubsub/pubsub.py

@@ -682,19 +682,18 @@ async def validate_msg(self, msg_forwarder: ID, msg: rpc_pb2.Message) -> None:
         # TODO: Implement throttle on async validators
 
         if len(async_topic_validators) > 0:
-            # TODO: Use a better pattern
-            final_result: bool = True
+            # Appends to lists are thread safe in CPython
+            results = []
 
             async def run_async_validator(func: AsyncValidatorFn) -> None:
-                nonlocal final_result
                 result = await func(msg_forwarder, msg)
-                final_result = final_result and result
+                results.append(result)
 
             async with trio.open_nursery() as nursery:
                 for async_validator in async_topic_validators:
                     nursery.start_soon(run_async_validator, async_validator)
 
-            if not final_result:
+            if not all(results):
                 raise ValidationError(f"Validation failed for msg={msg}")
 
     async def push_msg(self, msg_forwarder: ID, msg: rpc_pb2.Message) -> None:

newsfragments/702.bugfix.rst

@@ -0,0 +1 @@
+Fixed an issue in `Pubsub` where async validators were not handled reliably under concurrency. Now uses a safe aggregator list for consistent behavior.