MongoDB connector currently does not support batching
so the batch_size option has no effect.
However we cannot remove the field, so we choose to hide it from
schema
This commit refactor the query_mode resource detection code according to
a suggestion from @zmstone. This commit should not contain any
functional change except for a change of the Kafka producer bridge
config.
This commit makes it possible to configure if a Kafka bridge should work
in query mode sync or async by setting the resource_opts.query_mode
configuration option.
Fixes:
https://emqx.atlassian.net/browse/EMQX-8631
See:
https://emqx.atlassian.net/wiki/spaces/P/pages/612368639/open+e5.1+remove+auto+restart+interval+from+buffer+worker+resource+options
Current problem:
In 5.0.x, we have two timer options that control the state changing of buffer worker
resources: auto_restart_interval and health_check_interval.
- auto_restart_interval controls how often the resource attempts to transition from
disconnected to connected.
- health_check_interval controls how often the resource is checked and potentially moved
from connected to disconnected or connecting.
The existence of two independent timers for very similar purposes is confusing to users,
QA and even developers. Also, an intimately related configuration is request_timeout,
which can interact badly with auto_restart_interval if the latter is poorly configured:
requests may always expire if request_timeout < auto_restart_interval and if the resource
enters the disconnected state. For health_check_interval, we attempt to derive a sane
default that gives requests a chance to retry (if request timeout is finite, then the
resource retries requests with a period of min(health_check_interval, request_timeout /
3).
Another problem with the separate auto_restart_interval is that its default value (60 s)
is too high when compared to the default request timeout and health check, leading to the
problems described above if not tuned.
Proposed solution:
We propose to drop auto_restart_interval in favor of health_check_interval, which will be
used for both disconnected -> connected and connected -> {disconnected, connecting}
transition checks. With that, the resource will attempt to reconnect at the same interval
as the health check, which currently is 15 s.
Also, as two smaller changes to accompany this one:
- Increase the default request_timeout from 15 s to 45 s.
- Rename request_timeout to request_ttl.
Fixes https://emqx.atlassian.net/browse/EMQX-10074
Otherwise, requests from those async workers, now retriable, might not
be retried until the buffer worker blocks for other reasons, which
might take a long time.
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.
