threshold based automatic query prioritization

[clintropolis]

Description

This PR is a follow-up to #9407 that adds a new interface QueryPrioritizationStrategy intended to enable implementations to automatically prioritize queries based on some criteria. As a proof of concept implementation of this functionality, it provides ThresholdBasedQueryDeprioritizationStrategy, which offers the 3 thresholds of: period from the current time of the query, duration of the interval of the query, and number of segments taking part in the query, described in #6993.

This strategy can be enabled by setting druid.query.scheduler.prioritization.strategy to threshold.

Property	Description	Default
druid.query.scheduler.prioritization.periodThreshold	ISO duration threshold for how old data can be queried before automatically adjusting query priority.	None
druid.query.scheduler.prioritization.durationThreshold	ISO duration threshold for maximum duration a queries interval can span before the priority is automatically adjusted.	None
druid.query.scheduler.prioritization.segmentCountThreshold	Number threshold for maximum number of segments that can take part in a query before its priority is automatically adjusted.	None
druid.query.scheduler.prioritization.adjustment	Amount to reduce the priority of queries which cross any threshold.	None

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths.
• added integration tests.
• been tested in a test Druid cluster.

[sascha-coenen]

AWESOME! I love it. This will be so useful.

If a query surpasses the thresholds several times, for instance it would be several times the segment threshold or the duration threshold would fit into the query time range several times, would the "adjustment" be decremented several times too?
With the laning being implemented, will this become an alternative to the 'adjustment" property, to specify different lanes based on the query weight?

[jihoonson]

nit: hmm, is 'no auto' = 'manual'? Just wondering what is a better name.

[himanshug]

"None prioritization strategy" ?

[clintropolis]

Hmm, after thinking about it, I think manual maybe makes the most sense, to be symmetrical with the ManualQueryLaningStrategy of #9492 because both rely on the user adding a value to the query context.

[himanshug]

nit: by rephrasing it to say, "... strategy lowers priority of queries that..." , we could make the heading be "Threshold prioritization strategy"

[clintropolis]

thanks for the review @jihoonson and @himanshug