Package uk.ac.starlink.ttools.cone

Class ParallelResultRowSequence

java.lang.Object
uk.ac.starlink.ttools.cone.ParallelResultRowSequence
All Implemented Interfaces:
Closeable, AutoCloseable, uk.ac.starlink.table.RowData, uk.ac.starlink.table.RowSequence, ConeQueryRowSequence, ConeResultRowSequence, uk.ac.starlink.util.Sequence
public class ParallelResultRowSequence extends Object implements ConeResultRowSequence
ConeResultRowSequence implementation which uses a fixed number of worker threads to dispatch cone queries in parallel. The result table has the same ordering as if they had been done in sequence.
Since:
18 Jan 2008
Author:
Mark Taylor

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_MAXPAR
    Default maximum value for the number of threads that should be permitted for a query.
    static final String
    MAXPAR_PROP
    Name of system property "service.maxparallel" which may be used to adjust the maximum parallelism.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ParallelResultRowSequence(ConeQueryRowSequence querySeq, ConeSearcher coneSearcher, ConeErrorPolicy errAct, Coverage coverage, boolean bestOnly, boolean distFilter, String distanceCol, int parallelism)
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
     
    Object
    getCell(int icol)
     
    uk.ac.starlink.table.StarTable
    getConeResult()
    Returns the result of the cone search for the current row of this sequence.
    double
    getDec()
    Get central declination for the current row's cone search request in degrees.
    long
    getIndex()
    Get the index in the underlying table to which the current row relates.
    static int
    getMaxParallelism()
    Returns the maximum parallelism value which should permitted in this JVM.
    double
    getRa()
    Get central right ascension for the current row's cone search request in degrees.
    double
    getRadius()
    Get search radius for the current row's cone search request in degrees.
    Object[]
    getRow()
     
    boolean
    next()
     

    Methods inherited from class java.lang.Object

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

  • Field Details

    • DEFAULT_MAXPAR

      public static final int DEFAULT_MAXPAR
      Default maximum value for the number of threads that should be permitted for a query.
      See Also:

    • MAXPAR_PROP

      public static final String MAXPAR_PROP
      Name of system property "service.maxparallel" which may be used to adjust the maximum parallelism. Only increase this value with great care since you run the risk of overloading servers and making yourself unpopular with data centres. As a rule, you should only increase this value if you have obtained permission from the data centres whose services on which you will be using the increased parallelism.
      See Also:

  • Constructor Details

    • ParallelResultRowSequence

      public ParallelResultRowSequence(ConeQueryRowSequence querySeq, ConeSearcher coneSearcher, ConeErrorPolicy errAct, Coverage coverage, boolean bestOnly, boolean distFilter, String distanceCol, int parallelism)
      Constructor.
      Parameters:
      querySeq - sequence providing cone search query parameters
      coneSearcher - cone search implementation
      errAct - defines action on cone search invocation error
      coverage - coverage for results, or null
      bestOnly - whether all results or just best are required
      distFilter - true to perform post-query filtering on results based on the distance between the query position and the result row position
      distanceCol - name of column to hold distance information in output table, or null
      parallelism - number of concurrent querying threads

  • Method Details

    • next

      public boolean next() throws IOException
      Specified by:
      next in interface uk.ac.starlink.table.RowSequence
      Specified by:
      next in interface uk.ac.starlink.util.Sequence
      Throws:
      IOException

    • getCell

      public Object getCell(int icol) throws IOException
      Specified by:
      getCell in interface uk.ac.starlink.table.RowData
      Specified by:
      getCell in interface uk.ac.starlink.table.RowSequence
      Throws:
      IOException

    • getRow

      public Object[] getRow() throws IOException
      Specified by:
      getRow in interface uk.ac.starlink.table.RowData
      Specified by:
      getRow in interface uk.ac.starlink.table.RowSequence
      Throws:
      IOException

    • getRa

      public double getRa() throws IOException
      Description copied from interface: ConeQueryRowSequence
      Get central right ascension for the current row's cone search request in degrees.
      Specified by:
      getRa in interface ConeQueryRowSequence
      Returns:
      right ascension
      Throws:
      IOException

    • getDec

      public double getDec() throws IOException
      Description copied from interface: ConeQueryRowSequence
      Get central declination for the current row's cone search request in degrees.
      Specified by:
      getDec in interface ConeQueryRowSequence
      Returns:
      declination
      Throws:
      IOException

    • getRadius

      public double getRadius() throws IOException
      Description copied from interface: ConeQueryRowSequence
      Get search radius for the current row's cone search request in degrees.
      Specified by:
      getRadius in interface ConeQueryRowSequence
      Returns:
      search radius
      Throws:
      IOException

    • getIndex

      public long getIndex() throws IOException
      Description copied from interface: ConeQueryRowSequence
      Get the index in the underlying table to which the current row relates. The identity of this underlying table is not specified by this interface, but must be understood by the creator and user of instances. In particular, the return value does not necessarily increment by one for each call to next.
      Specified by:
      getIndex in interface ConeQueryRowSequence
      Returns:
      row index
      Throws:
      IOException

    • getConeResult

      public uk.ac.starlink.table.StarTable getConeResult() throws IOException
      Description copied from interface: ConeResultRowSequence
      Returns the result of the cone search for the current row of this sequence. The work will typically be done using ConeMatcher.getConeResult(uk.ac.starlink.ttools.cone.ConeSearcher, uk.ac.starlink.ttools.cone.ConeErrorPolicy, boolean, boolean, java.lang.String, double, double, double).

      If no records in the cone are found, the return value may either be null or (preferably) an empty table with the correct columns.

      Specified by:
      getConeResult in interface ConeResultRowSequence
      Returns:
      table giving rows strictly within the match criteria for the current row of this cone query sequence, or null
      Throws:
      IOException

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface uk.ac.starlink.table.RowSequence
      Throws:
      IOException

    • getMaxParallelism

      public static int getMaxParallelism()
      Returns the maximum parallelism value which should permitted in this JVM. The purpose of this is to set a limit to the number of concurrent queries that an irresponsible/careless user can hit a server with. The value can be adjusted using the MAXPAR_PROP system property. Note that this method is not used by this class, i.e. the maximum is not imposed here, it should be imposed by calling code.
      Returns:
      parallelism limit