Nothing replaces a read-only file on Windows, neither a rename over it
nor an in-place write, so the opt-in that keeps a read-only config
saveable clears the attribute first; without that the test for it could
not pass there. A failed config write still leaves the flag dirty, as
before this change, but the next attempt waits ten seconds, so the idle
handler does not repeat a hopeless write on every event.
A file moved aside by a refused rename can be the only copy left if the
process dies in between, so the sweep puts such a file back when its
original is missing rather than removing it, and the directory-only
errors that could only come from a directory target no longer trigger
the move-aside at all. The sweep after a write runs only under the data
dir and at most once an hour per directory, so a batch of saves does not
read the directory once per file and an export into a user's folder
never reads that folder. A lock holder that never lets go doubles the
cool-down for each timeout in a row, up to five minutes, instead of
costing a stall every ten seconds for good.
Hanif Koh
b7102a524b