[LUCENE-2955] Add utitily class to manage NRT reopening

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3, 4.0-ALPHA
• Component/s: core/index
• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Created: 09/Mar/11 16:55
• Updated: 28/Aug/22 12:42
• Resolved: 14/Jun/11 16:10

Description

I created a simple class, NRTManager, that tries to abstract away some
of the reopen logic when using NRT readers.

You give it your IW, tell it min and max nanoseconds staleness you can
tolerate, and it privately runs a reopen thread to periodically reopen
the searcher.

It subsumes the SearcherManager from LIA2. Besides running the reopen
thread, it also adds the notion of a "generation" containing changes
you've made. So eg it has addDocument, returning a long. You can
then take that long value and pass it back to the getSearcher method
and getSearcher will return a searcher that reflects the changes made
in that generation.

This gives your app the freedom to force "immediate" consistency (ie
wait for the reopen) only for those searches that require it, like a
verifier that adds a doc and then immediately searches for it, but
also use "eventual consistency" for other searches.

I want to also add support for the new "applyDeletions" option when
pulling an NRT reader.

Also, this is very new and I'm sure buggy – the concurrency is either
wrong over overly-locking. But it's a start...