Package org.apache.lucene.monitor

Class ParallelMatcher<T extends QueryMatch>

java.lang.Object
org.apache.lucene.monitor.CandidateMatcher<T>
org.apache.lucene.monitor.ParallelMatcher<T>
Type Parameters:
T - the QueryMatch type returned
public class ParallelMatcher<T extends QueryMatch> extends CandidateMatcher<T>
Matcher class that runs matching queries in parallel.

This class delegates the actual matching to separate CandidateMatcher classes, built from a passed in MatcherFactory.

Use this when individual queries can take a long time to run, and you want to minimize latency. The matcher distributes queries amongst its worker threads using a BlockingQueue, and synchronization overhead may affect performance if the individual queries are very fast.

See Also:

  • Method Details

    • matchQuery

      protected void matchQuery(String queryId, Query matchQuery, Map<String,String> metadata) throws IOException
      Description copied from class: CandidateMatcher
      Runs the supplied query against this CandidateMatcher's set of documents, storing any resulting match, and recording the query in the presearcher hits
      Specified by:
      matchQuery in class CandidateMatcher<T extends QueryMatch>
      Parameters:
      queryId - the query id
      matchQuery - the query to run
      metadata - the query metadata
      Throws:
      IOException - on IO errors

    • resolve

      public T resolve(T match1, T match2)
      Description copied from class: CandidateMatcher
      If two matches from the same query are found (for example, two branches of a disjunction), combine them.
      Specified by:
      resolve in class CandidateMatcher<T extends QueryMatch>
      Parameters:
      match1 - the first match found
      match2 - the second match found
      Returns:
      a Match object that combines the two

    • doFinish

      protected void doFinish()
      Description copied from class: CandidateMatcher
      Called when all monitoring of a batch of documents is complete
      Overrides:
      doFinish in class CandidateMatcher<T extends QueryMatch>

    • factory

      public static <T extends QueryMatch> MatcherFactory<T> factory(ExecutorService executor, MatcherFactory<T> matcherFactory, int threads)
      Create a new MatcherFactory for a ParallelMatcher
      Type Parameters:
      T - the type of QueryMatch generated
      Parameters:
      executor - the ExecutorService to use
      matcherFactory - the MatcherFactory to use to create submatchers
      threads - the number of threads to use

    • factory

      public static <T extends QueryMatch> MatcherFactory<T> factory(ExecutorService executor, MatcherFactory<T> matcherFactory)
      Create a new MatcherFactory for a ParallelMatcher

      This factory will create a ParallelMatcher that uses as many threads as there are cores available to the JVM (as determined by Runtime.getRuntime().availableProcessors()).

      Type Parameters:
      T - the type of QueryMatch generated
      Parameters:
      executor - the ExecutorService to use
      matcherFactory - the MatcherFactory to use to create submatchers