Package com.yahoo.prelude.fastsearch

Class VespaBackEndSearcher

  • All Implemented Interfaces:
    com.yahoo.component.Component, java.lang.Comparable<com.yahoo.component.Component>
    Direct Known Subclasses:
    FastSearcher, VdsStreamingSearcher
    public abstract class VespaBackEndSearcher
extends PingableSearcher
    Superclass for backend searchers.
    Author:
    baldersheim

    • Constructor Detail

      • VespaBackEndSearcher

        public VespaBackEndSearcher()

    • Method Detail

      • getName

        public final java.lang.String getName()

      • getDefaultDocsumClass

        protected final java.lang.String getDefaultDocsumClass()

      • getLogger

        public final java.util.logging.Logger getLogger()
        Description copied from class: Searcher
        Returns a logger unique for the instance subclass
        Overrides:
        getLogger in class Searcher

      • doSearch2

        protected abstract Result doSearch2​(Query query,
                                    Execution execution)
        Searches a search cluster This is an endpoint - searchers will never propagate the search to any nested searcher.
        Parameters:
        query - the query to search
        execution - the query execution context

      • doPartialFill

        protected abstract void doPartialFill​(Result result,
                                      java.lang.String summaryClass)

      • summaryNeedsQuery

        public boolean summaryNeedsQuery​(Query query)
        Returns whether we need to send the query when fetching summaries. This is necessary if the query requests summary features or dynamic snippeting

      • getServerId

        public java.lang.String getServerId()

      • transformQuery

        protected void transformQuery​(Query query)

      • search

        public Result search​(Query query,
                     Execution execution)
        Description copied from class: Searcher
        Override this to implement your searcher.

        Searcher implementation subclasses will, depending on their type of logic, do one of the following:

        • Query processors: Access the query, then call execution.search and return the result
        • Result processors: Call execution.search to get the result, access it and return
        • Sources (which produces results): Create a result, add the desired hits and return it.
        • Federators (which forwards the search to multiple subchains): Call search on the desired subchains in parallel and get the results. Combine the results to one and return it.
        • Workflows: Call execution.search as many times as desired, using different queries. Eventually return a result.

        Hits come in two kinds - concrete hits are actual content of the kind requested by the user, meta hits are hits which provides information about the collection of hits, on the query, the service and so on.

        The query specifies a window into a larger result list that must be returned from the searcher through hits and offset; Searchers which returns list of hits in the top level in the result must return at least hits number of hits (or if impossible; all that are available), starting at the given offset. In addition, searchers are allowed to return any number of meta hits (although this number is expected to be low). For hits contained in nested hit groups, the concept of a window defined by hits and offset is not well defined and does not apply.

        Error handling in searchers:

        • Unexpected events: Throw any RuntimeException. This query will fail with the exception message, and the error will be logged
        • Expected events: Create (new Result(Query, ErrorMessage) or add result.setErrorIfNoOtherErrors(ErrorMessage) an error message to the Result.
        • Recoverable user errors: Add a FeedbackHit explaining the condition and how to correct it.
        Specified by:
        search in class Searcher
        Parameters:
        query - the query
        Returns:
        the result of making this query

      • fill

        public void fill​(Result result,
                 java.lang.String summaryClass,
                 Execution execution)
        Description copied from class: Searcher
        Fill hit properties with data using the given summary class. Calling this on already filled results has no cost.

        This needs to be overridden by federating searchers to contact search sources again by propagating the fill call down through the search chain, and by source searchers which talks to fill capable backends to request the data to be filled. Other searchers do not need to override this.

        Overrides:
        fill in class Searcher
        Parameters:
        result - the result to fill
        summaryClass - the name of the collection of fields to fetch the values of, or null to use the default

      • fillHits

        protected VespaBackEndSearcher.FillHitsResult fillHits​(Result result,
                                                       DocsumPacket[] packets,
                                                       java.lang.String summaryClass)
        Fills the hits.
        Returns:
        the number of hits that we did not return data for, and an optional error message. when things are working normally we return 0.

      • isLoggingFine

        protected boolean isLoggingFine()

      • shutDown

        public void shutDown()