Issue
If index.search(query) in tcp_mojifinder.py returns empty result, it crashes TCP because asyncio.StreamWriter.writelines(data) raises AssertionError: Data should not be empty error if data is an empty iterable.
How to reproduce
Start the TCP server
% ./tcp_mojifinder.py
Building index.
Serving on ('127.0.0.1', 2323). Hit CTRL-C to stop.
...Connect to the TCP server and send a search query which returns no results, e.g. missing
% nc localhost 2323
?> missing
%
The TCP server terminal will spit out an error stack trace like
% ./tcp_mojifinder.py
Building index.
Serving on ('127.0.0.1', 2323). Hit CTRL-C to stop.
From ('127.0.0.1', 63253): 'missing'
Unhandled exception in client_connected_cb
transport: <_SelectorSocketTransport fd=7 read=polling write=<idle, bufsize=0>>
Traceback (most recent call last):
File "/Users/tim/projects/python/example-code-2e/21-async/mojifinder/./tcp_mojifinder.py", line 33, in finder
results = await search(query, index, writer) # <13>
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/tim/projects/python/example-code-2e/21-async/mojifinder/./tcp_mojifinder.py", line 48, in search
writer.writelines(lines) # <4>
~~~~~~~~~~~~~~~~~^^^^^^^
File "/opt/homebrew/Cellar/[email protected]/3.13.5/Frameworks/Python.framework/Versions/3.13/lib/python3.13/asyncio/streams.py", line 343, in writelines
self._transport.writelines(data)
~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/opt/homebrew/Cellar/[email protected]/3.13.5/Frameworks/Python.framework/Versions/3.13/lib/python3.13/asyncio/selector_events.py", line 1174, in writelines
self._write_ready()
~~~~~~~~~~~~~~~~~^^
File "/opt/homebrew/Cellar/[email protected]/3.13.5/Frameworks/Python.framework/Versions/3.13/lib/python3.13/asyncio/selector_events.py", line 1090, in _write_sendmsg
assert self._buffer, 'Data should not be empty'
^^^^^^^^^^^^
AssertionError: Data should not be empty
Issue
If
index.search(query)intcp_mojifinder.pyreturns empty result, it crashes TCP becauseasyncio.StreamWriter.writelines(data)raisesAssertionError: Data should not be emptyerror ifdatais an empty iterable.How to reproduce
Start the TCP server
% ./tcp_mojifinder.py Building index. Serving on ('127.0.0.1', 2323). Hit CTRL-C to stop. ...Connect to the TCP server and send a search query which returns no results, e.g.
missingThe TCP server terminal will spit out an error stack trace like