Rails 6 introduces retries per-exception, instead of a global count of
retries. Because ActiveJob 5.2 doesn't serialize the execution count
per-exception, when ActiveJob 6.0 picks up an "old" job it can't know
the exception count in the new format.
This can also be an issue if AJ 6.0 serializes a new job with
exception_executions which is later picked up by AJ 5.2, which would
clear exception_executions (since it has no knowledge of it).
Previously we handled this by resetting exception_executions, if it
wasn't defined on a job, which could result in the worst case retrying
the job 2x the times we should.
This commit changes how we handle loading a legacy job: instead of
resetting exception_executions, we instead will always use the global
executions count.
This way, jobs which only have one retry_on (and didn't have a behaviour
change in AJ 6) are backwards-and-forwards-compatible with counts
respected exactly.
Jobs with multiple retry_on will revert to the AJ5.2 behaviour if they
were ever run under AJ5.2.
Individual execution counters were introduced in #34352. However
`#determine_delay` which is used to calculate retry delay still uses the
global counter. This commit fixes it.
Previously, by extending ActiveJob::TestCase, the test adapter provided
for tests was being used always, in all executions where supposedly
different adapters were being used. As a consequence, some bugs visible
only for some adapters might have gone undetected. This commit changes
that, skipping queue adapters for which we can't test scheduling jobs
with a delay.
Also, make tests and examples for individual execution counters
clearer, as it wasn't entierly clear what would happen in this case:
```
retry_on CustomException, OtherException, attempts: 3
```
The job would be retried at most 3 times in total, for both
CustomException and OtherException. To have the job retry 3 times at
most for each exception individually, the following retry_on
declarations are necessary:
```
retry_on CustomException, attempts: 3
retry_on OtherException, attempts: 3
```
* Keep executions for each specific declaration
Fixes#34337
ActiveJob used the global executions counter to control the number of
times a job should be retried. The problem with this approach was that
in case a job raised different exceptions during its executions they
weren't retried the number of times defined by their `attemps` number.
**Example:**
Having the following job:
```ruby
class BuggyJob < ActiveJob::Base
retry_on CustomException, attemps: 3
retry_on OtherException, attempts: 3
end
```
If the job raised `CustomException` in the first two executions and then
it raised `OtherException`, the job wasn't retried anymore because the
global executions counter was already indicating 3 attempts.
With this patch each `retry_on` declaration has its specific counter so
that the first two executions that raise `CustomException` don't affect
the retries count that future exceptions may have.
* Revert "clarifies documentation around the attempts arugment to retry_on"
This reverts commit 86aa8f8c56.
Currently, the execution count increments after deserializes arguments.
Therefore, if an error occurs with deserialize, it retries indefinitely.
In order to prevent this, the count is moved before deserialize.
Fixes#33344.
