msgstore: fix deadlock in thread builder

When scrolling while the thread builder is running, aerc freezes. This
issue can be easily reproduced by keeping the down arrow pressed while
a folder is loading with local threading enabled.

This is caused by the threadCallback function calling store.Select which
acquires threadsMutex. However, threadCallback is already called with
threadsMutex acquired, causing a deadlock.

Fix the issue by adding a new selectPriv function that does not acquire
the lock and call this one in threadCallback *and* store.Select. Do not
reset threadCallback to nil as it was before.

Fixes: 6b8e0b19d35a ("split: refactor to prevent stuck splits")
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Thomas Vigouroux <me@vigoux.giize.com>

0 files changed, 0 insertions, 0 deletions