Iteration methods on LRU were removed because they were not
thread-safe and it's not clear that making them thread-safe is the
correct thing to do, so not providing them seems saner.
I thought I'd looked for usages of the LRU but apparently didn't look
hard enough as I missed that it's used by the cron workers (apparently
using the threaded server we only run crons for dbs currently living
in the registry cache, the more you know).
Convert these to iterating on the LRU's internal mapping, and also
don't iterate on the LRU to clear its entries one by one when we can
just clear the entire thing safely, although Registry.delete_all
really seems completely unused.
closesodoo/odoo#49023
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>