com.yahoo.prelude.searcher

Class BlendingSearcher

java.lang.Object

com.yahoo.component.AbstractComponent

com.yahoo.component.chain.ChainedComponent

com.yahoo.processing.Processor

com.yahoo.search.Searcher

com.yahoo.prelude.searcher.BlendingSearcher

All Implemented Interfaces:

com.yahoo.component.Component, Comparable<com.yahoo.component.Component>

public class BlendingSearcher
extends Searcher

Flattens a result consisting of multiple hit groups containing hits into a single flat list of hits.

Author:

Bob Travis, Steinar Knutsen, Arne Fossaa

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	BlendingSearcher.BasicMerger
private class	BlendingSearcher.DocumentMerger
private class	BlendingSearcher.UniqueMerger

Field Summary

Fields

Modifier and Type	Field and Description
static String	BLENDING
private String	documentId

Fields inherited from class com.yahoo.component.AbstractComponent

isDeconstructable

Constructor Summary

Constructors

Constructor and Description
BlendingSearcher(com.yahoo.component.ComponentId id, com.yahoo.container.QrSearchersConfig cfg)
BlendingSearcher(String blendingDocumentId) Only for legacy tests.

Method Summary

Modifier and Type	Method and Description
protected Result	blendResults(Result result, Query q, int offset, int hits, Execution execution) Produce a single blended result list from a group of hitgroups.
private Result	blendResultsDirectly(Result result, Query q, int offset, int hits, List<HitGroup> groups, Execution execution)
private Result	blendResultsUniquely(Result result, Query q, int offset, int hits, List<HitGroup> groups, Execution execution)
void	fill(Result result, String summaryClass, Execution execution) Fills this result by forwarding to the right chained searchers
Result	search(Query query, Execution execution) Override this to implement your searcher.
private Result	sortAndTrimResults(Result result, Query q, int offset, int hits, Execution execution)

Methods inherited from class com.yahoo.search.Searcher

ensureFilled, getLogger, process, toString

Methods inherited from class com.yahoo.component.chain.ChainedComponent

getAnnotatedDependencies, getDefaultAnnotatedDependencies, getDependencies, initDependencies

Methods inherited from class com.yahoo.component.AbstractComponent

clone, compareTo, deconstruct, getClassName, getId, getIdString, hasInitializedId, initId, isDeconstructable, setIsDeconstructable

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

BLENDING

public static final String BLENDING

See Also:

Constant Field Values

documentId

private final String documentId

Constructor Detail

BlendingSearcher

@Inject
public BlendingSearcher(com.yahoo.component.ComponentId id,
                                com.yahoo.container.QrSearchersConfig cfg)

BlendingSearcher

public BlendingSearcher(String blendingDocumentId)

Only for legacy tests.

Method Detail

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,
                 String summaryClass,
                 Execution execution)

Fills this result by forwarding to the right chained searchers

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

blendResults

protected Result blendResults(Result result,
                              Query q,
                              int offset,
                              int hits,
                              Execution execution)

Produce a single blended result list from a group of hitgroups. It is assumed that the results are ordered in hitgroups. If not, the blend will not be performed

sortAndTrimResults

private Result sortAndTrimResults(Result result,
                                  Query q,
                                  int offset,
                                  int hits,
                                  Execution execution)

blendResultsDirectly

private Result blendResultsDirectly(Result result,
                                    Query q,
                                    int offset,
                                    int hits,
                                    List<HitGroup> groups,
                                    Execution execution)

blendResultsUniquely

private Result blendResultsUniquely(Result result,
                                    Query q,
                                    int offset,
                                    int hits,
                                    List<HitGroup> groups,
                                    Execution execution)