Package com.yahoo.search.searchers

Class ConnectionControlSearcher

java.lang.Object
com.yahoo.component.AbstractComponent
com.yahoo.component.chain.ChainedComponent
com.yahoo.processing.Processor
com.yahoo.search.Searcher
com.yahoo.search.searchers.ConnectionControlSearcher
All Implemented Interfaces:
com.yahoo.component.Component, com.yahoo.component.Deconstructable, Comparable<com.yahoo.component.Component>
public class ConnectionControlSearcher extends Searcher
Searcher which can enforce HTTP connection close based on query properties.

This searcher informs the client to close a persistent HTTP connection if the connection is older than the configured max lifetime. This is done by adding the "Connection" HTTP header with the value "Close" to the result.

The searcher reads the query property "connectioncontrol.maxlifetime", which is an integer number of seconds, to get the value for maximum connection lifetime. Setting it to zero will enforce connection close independently of the age of the connection. Typical usage would be as follows:

  1. Add the ConnectionControlSearcher to the default search chain of your application. (It has no special ordering considerations.)
  2. For the default query profile of your application, set a reasonable value for "connectioncontrol.maxlifetime". The definition of reasonable will be highly application dependent, but it should always be less than the grace period when taking the container out of production traffic.
  3. Deploy application. The container will now inform clients to close connections/reconnect within the configured time limit.
Author:
frodelu, Steinar Knutsen

  • Field Summary

    Fields inherited from class com.yahoo.component.AbstractComponent

    isDeconstructable

  • Constructor Summary

    Constructors
    Constructor
    Description
    ConnectionControlSearcher()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static ConnectionControlSearcher
    createTestInstance(LongSupplier clock)
    Create a searcher instance suitable for unit tests.
    Result
    search(Query query, Execution execution)
    Override this to implement your searcher.

    Methods inherited from class com.yahoo.search.Searcher

    ensureFilled, fill, 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

  • Constructor Details

    • ConnectionControlSearcher

      public ConnectionControlSearcher()

  • Method Details

    • createTestInstance

      public static ConnectionControlSearcher createTestInstance(LongSupplier clock)
      Create a searcher instance suitable for unit tests.
      Parameters:
      clock - a simulated or real clock behaving similarly to System.currentTimeMillis()
      Returns:
      a fully initialised instance

    • 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