mirror of
https://github.com/sbt/sbt.git
synced 2026-09-04 16:54:29 +02:00
BrianHotoppandClaude Fable 5
1bde3d23a9
One attached client answering the sbt/terminalpropertiesquery request badly, or slower than 5 seconds, could freeze the whole server for every client: - The response handler dropped malformed responses (response.foreach(buffer.put)) instead of falling back to a default like every sibling handler, so the updater thread waiting on the queue timed out with the properties reference still null. - getProperties(block = true) waits while properties is null, but nothing completes it after the updater's one-shot 5-second poll times out: waiters woke from the notify, saw null, and waited again with no updater outstanding. The 1-second lastUpdate throttle also let a caller start waiting with no query in flight at all, and the wait condition was checked outside the pending monitor, losing wakeups that fired between the check and the wait. - A response arriving after the poll timeout was delivered into a queue that was never deregistered, so it neither set properties nor woke anyone. The threads that block here include the command loop iterating channels and the fast-track thread handling attach and cancel, so one bad or briefly-stalled client wedged prompts, Ctrl-C, and command dispatch server-wide until that client disconnected. The properties response handler now falls back to a default like its siblings; the updater expires its query on timeout, deregistering it (rescuing a response that raced in) and completing properties with the empty default so waiters always make progress; and both wait sites hold the pending monitor and gate on the query in flight. waitForPending gets the same treatment, since it seeds lazy vals whose initialization otherwise parks every thread touching them. Regression test: a raw-protocol session that answers every server request with a result of the wrong shape attaches interactively; a well-behaved batch client must then still be served twice. Fails on develop with a three-minute timeout (the server is frozen), passes with this change. A unit spec pins the expiry semantics, including the late-response rescue. Co-authored-by: Claude Fable 5 <[email protected]>