LUCENE-9406: Add IndexWriterEventListener to track events in IndexWriter #2342
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| MergePolicy.OneMerge nextMerge = null; | ||
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| if (pendingMerges.size() > 0) { | ||
| // nocommit getting OneMerge instance here via mergeSource.getNextMerge() will |
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How about passing the pendingMerges to the event listener instead? (Sorry if I asked for OneMerge on the issue! MergeSpecification is better since it can hold multiple merges, allows event listener to log things like how many merges were requested during commit, etc.).
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No problem! From the context I assume you are actually meaning to pass pointInTimeMerges into event listener, since pendingMerges is of type Deque<MergePolicy.OneMerge>? I've pushed a commit to use pointInTimeMerges for now.
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| // Test basic semantics of merge on commit and events recording invocation | ||
| public void testMergeOnCommitWithEventListener() throws IOException { |
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You might also edit LuceneTestCase.newIndexWriterConfig to randomly swap in a MockIndexWriterEventListener just to exercise this listener in any tests using that API, which is quite a few. It could uncover times when we accidentally break something when this listener is invoked ...
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Makes sense. Added.
…r randomly into LuceneTestCase.newIndexConfig
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I think it's good overall but I'm wondering whether it makes sense to make that field volatile... do we want to allow changing listeners over index writer lifecycle? I think it should be a regular field and IW should just read it once (and set forever). |
Thanks for the feedback Dawid! I thought about this a bit as well when I noticed most of the other fields are volatile, but I can't decide for sure which direction to go as I don't have enough context information about the different use cases IW may need to support in the wild, so I ended up following the existing pattern here. However, I do feel that it may not hurt for application to have the freedom to switch event listener in the middle if situation or need dictates (i.e. a service application containing Lucene may need to switch event listener if it exposes an API for its client to choose how the IW event stream to be sent and stored) ? |
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If such a situation arises folks will have the ability to write a custom proxy listener with the ability to switch, add and/or remove delegates. This keeps the freedom to do anything you said and at the same time simplifies implementation (and concurrency-issues) on IW side? |
Ah that's very true! I've pushed a commit to remove volatile then. Please let me know if it looks good. |
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Circling back to this PR as I just realized I have forgotten about it.. :D Thanks @dweiss for the review! @mikemccand do you think this PR is ready now? Anything else you would like me to improve on? |
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Looks good to me. I've merged this in, sorry for the delay. |
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No worry! Thanks for the review and merge! |
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Woops, sorry for the belated response, and thank you @zacharymorn for creating this and @dweiss for merging -- it looks great! We can now add other events to track incrementally over time ... |
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No problem, and thanks for the review feedback as well Michael! |
Description / Solution
Add IndexWriterEventListener interface to track events in IndexWriter
Tests
Note: precommit is currently failing due to nocommit comment
Checklist
Please review the following and check all that apply:
masterbranch../gradlew check.