PYTHON-4982 Fix spurious network errors when using asyncio

Author: ShaneHarvey

pymongo/network_layer.py

@@ -71,6 +71,7 @@
 async def async_sendall(sock: Union[socket.socket, _sslConn], buf: bytes) -> None:
     timeout = sock.gettimeout()
     sock.settimeout(0.0)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SOCK_NONBLOCK, 1)
     loop = asyncio.get_event_loop()
     try:
         if _HAVE_SSL and isinstance(sock, (SSLSocket, _sslConn)):
@@ -258,6 +259,7 @@ async def async_receive_data(
         timeout = sock_timeout
 
     sock.settimeout(0.0)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SOCK_NONBLOCK, 1)
     loop = asyncio.get_event_loop()
     cancellation_task = asyncio.create_task(_poll_cancellation(conn))
     try:
@@ -288,6 +290,7 @@ async def async_receive_data_socket(
     timeout = sock_timeout
 
     sock.settimeout(0.0)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SOCK_NONBLOCK, 1)
     loop = asyncio.get_event_loop()
     try:
         if _HAVE_SSL and isinstance(sock, (SSLSocket, _sslConn)):