KOJO-127 | StateTransitionLogger LADR #74
Conversation
| Job state transitions are persisted to RDBMS in `Neighborhoods\Kojo\State\Service::applyRequest()`. | ||
| To that logic we will add another `INSERT` into a new table: `kojo_job_state_transitions` (working title). | ||
| The schema of that table will include all job information (ID, type, etc.) as well as process information (execution environment, PID, etc.). | ||
| Those two statements will be wrapped in a database transaction to ensure that nothing is written to `kojo_job_state_transitions` unless the actual transition succeeds. |
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@mucha55 how are you planning on using PDO to accomplish this with user-land transactions? testing PDO::inTransaction?
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Doctrine DBAL supports "nested" transactions, but even without them this is fine: If there's a userspace transaction happening, because it being rolled back will mean the job state never changes, which means there shouldn't be anything written to kojo_job_state_transitions anyway
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Per an offline discussion, we have to use \PDO for managing the transaction, since a Doctrine Connection isn't aware of what happens in the \PDO connection that it was instantiated with
| There are multiple unknowns with this design which could cause it to become infeasible to implement, in which case we'd have to go with the approach outlined in Alternative 3. | ||
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| ## Unresolved Questions | ||
| * Should we log when a job is created (i.e. scheduled)? |
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On the surface I would answer "yes". When an execution cluster is constrained on resources or limited by process pool size, there may be jobs that never exit the waiting state. In this condition, we'd never see a StateTransitionLogger message about that job, and only polling kojo_job would display it.
Is there an implementation detail that makes logging on creation difficult?
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After we talked through the implementation a little bit last week, I realized that including job creation is easier than not including it
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