Package uk.ac.starlink.ttools.cone
Class ParallelResultRowSequence
- java.lang.Object
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- uk.ac.starlink.ttools.cone.ParallelResultRowSequence
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- All Implemented Interfaces:
uk.ac.starlink.table.RowSequence
,ConeQueryRowSequence
,ConeResultRowSequence
public class ParallelResultRowSequence extends java.lang.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
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Field Summary
Fields Modifier and Type Field Description static int
DEFAULT_MAXPAR
Default maximum value for the number of threads that should be permitted for a query.static java.lang.String
MAXPAR_PROP
Name of system property "service.maxparallel" which may be used to adjust the maximum parallelism.
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Constructor Summary
Constructors Constructor Description ParallelResultRowSequence(ConeQueryRowSequence querySeq, ConeSearcher coneSearcher, ConeErrorPolicy errAct, Coverage coverage, boolean bestOnly, boolean distFilter, java.lang.String distanceCol, int parallelism)
Constructor.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
java.lang.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.java.lang.Object[]
getRow()
boolean
next()
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Field Detail
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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
,getMaxParallelism()
, Constant Field Values
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MAXPAR_PROP
public static final java.lang.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:
DEFAULT_MAXPAR
,getMaxParallelism()
, Constant Field Values
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Constructor Detail
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ParallelResultRowSequence
public ParallelResultRowSequence(ConeQueryRowSequence querySeq, ConeSearcher coneSearcher, ConeErrorPolicy errAct, Coverage coverage, boolean bestOnly, boolean distFilter, java.lang.String distanceCol, int parallelism)
Constructor.- Parameters:
querySeq
- sequence providing cone search query parametersconeSearcher
- cone search implementationerrAct
- defines action on cone search invocation errorcoverage
- coverage for results, or nullbestOnly
- whether all results or just best are requireddistFilter
- true to perform post-query filtering on results based on the distance between the query position and the result row positiondistanceCol
- name of column to hold distance information in output table, or nullparallelism
- number of concurrent querying threads
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Method Detail
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next
public boolean next() throws java.io.IOException
- Specified by:
next
in interfaceuk.ac.starlink.table.RowSequence
- Throws:
java.io.IOException
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getCell
public java.lang.Object getCell(int icol) throws java.io.IOException
- Specified by:
getCell
in interfaceuk.ac.starlink.table.RowSequence
- Throws:
java.io.IOException
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getRow
public java.lang.Object[] getRow() throws java.io.IOException
- Specified by:
getRow
in interfaceuk.ac.starlink.table.RowSequence
- Throws:
java.io.IOException
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getRa
public double getRa() throws java.io.IOException
Description copied from interface:ConeQueryRowSequence
Get central right ascension for the current row's cone search request in degrees.- Specified by:
getRa
in interfaceConeQueryRowSequence
- Returns:
- right ascension
- Throws:
java.io.IOException
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getDec
public double getDec() throws java.io.IOException
Description copied from interface:ConeQueryRowSequence
Get central declination for the current row's cone search request in degrees.- Specified by:
getDec
in interfaceConeQueryRowSequence
- Returns:
- declination
- Throws:
java.io.IOException
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getRadius
public double getRadius() throws java.io.IOException
Description copied from interface:ConeQueryRowSequence
Get search radius for the current row's cone search request in degrees.- Specified by:
getRadius
in interfaceConeQueryRowSequence
- Returns:
- search radius
- Throws:
java.io.IOException
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getIndex
public long getIndex() throws java.io.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 tonext
.- Specified by:
getIndex
in interfaceConeQueryRowSequence
- Returns:
- row index
- Throws:
java.io.IOException
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getConeResult
public uk.ac.starlink.table.StarTable getConeResult() throws java.io.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 usingConeMatcher.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 interfaceConeResultRowSequence
- Returns:
- table giving rows strictly within the match criteria for the current row of this cone query sequence, or null
- Throws:
java.io.IOException
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close
public void close() throws java.io.IOException
- Specified by:
close
in interfaceuk.ac.starlink.table.RowSequence
- Throws:
java.io.IOException
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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 theMAXPAR_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
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