Co-authored-by: Thales Macedo Garitezi <thalesmg@gmail.com>
Co-authored-by: Stefan Strigler <stefan.strigler@emqx.io>
Co-authored-by: Zaiming (Stone) Shi <zmstone@gmail.com>
Several bridges should be able to share a connector pool defined by a
single connector. The connectors should be possible to enable and
disable similar to how one can disable and enable bridges. There should
also be an API for checking the status of a connector and for
add/edit/delete connectors similar to the current bridge API.
Issues:
https://emqx.atlassian.net/browse/EMQX-10805
Using `simple_one_for_one` has a potential race condition issue where
we read the PID of the resource manager before trying to remove a
resource, and then that PID changes because it was either dead at
first, or it crashed and changed, and later we use this stale PID to
try to remove it from the supervisor. Under such circumstances, the
restarting child might linger in the supervisor, leaking resources.
By using the resource ID itself as a child ID (and using `one_for_one`
restart strategy), we ensure the child is truly removed.
Also use it instead of a custom ETS table for simplicity and
better consistency. This has drawbacks though: expect slightly
increased load on gproc gen_server due to how `gproc:set_value/2`
works.
Before this change, a separate `manager_id` / `instance_id` was used
as resource manager id, which made connector interface somewhat
inconsistent: part of function calls to connector implementation
used instance id as first argument while the rest used resource id
itself.
Kjell Winblad