gr.uoa.di.madgik.searchlibrary.operatorlibrary.merge
Class MergeOp

java.lang.Object
  gr.uoa.di.madgik.searchlibrary.operatorlibrary.merge.MergeOp

public class MergeOp
extends Object

Operator class used to create a merged ResultSet output from the contents of an array of input ResultSet

Author:

UoA

Field Summary

static int	BufferCapacityDef The default capacity of the RecordWriters and, if applicable, of all IRecordReaders' buffers
static OperationMode	OperationModeDef The default operation mode.
static String	RankFieldNameDef The default name of the field which contains the record rank.
static long	TimeoutDef The default timeout used by the IRecordWriter and all IRecordReaders.
static TimeUnit	TimeUnitDef The default timeout unit used by the RecordWriter and all IRecordReaders.

Constructor Summary

MergeOp(URI[] locators, OperationMode operationMode, long timeout, TimeUnit timeUnit, int bufferCapacity, StatsContainer stats)
Creates a new MergeOp with configurable operation mode and timeout

MergeOp(URI[] locators, OperationMode operationMode, long timeout, TimeUnit timeUnit, StatsContainer stats)
Creates a new MergeOp with configurable operation mode and timeout

MergeOp(URI[] locators, OperationMode operationMode, StatsContainer stats)
Creates a new MergeOp with configurable operation mode and the default timeout used both for readers and the writer

MergeOp(URI[] locators, StatsContainer stats)
Creates a new MergeOp with the default operation mode and the default timeout used both for readers and the writer

Method Summary

URI	compute() Performs the merging operation
void	setQuery(String query)
void	setRankFieldName(String rankFieldName) Sets the name of the field which contains the record rank Used only if operationMode is set to OperationMode.Sort

Methods inherited from class java.lang.Object

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

Field Detail

OperationModeDef

public static final OperationMode OperationModeDef

The default operation mode. Currently set to OperationMode.FIFO

TimeoutDef

public static final long TimeoutDef

The default timeout used by the IRecordWriter and all IRecordReaders. Currently set to 60.

See Also:

Constant Field Values

TimeUnitDef

public static final TimeUnit TimeUnitDef

The default timeout unit used by the RecordWriter and all IRecordReaders. The current default unit is seconds.

BufferCapacityDef

public static final int BufferCapacityDef

The default capacity of the RecordWriters and, if applicable, of all IRecordReaders' buffers

See Also:

Constant Field Values

RankFieldNameDef

public static final String RankFieldNameDef

The default name of the field which contains the record rank. Used if operationMode is set to OperationMode.Sort

See Also:

Constant Field Values

Constructor Detail

MergeOp

public MergeOp(URI[] locators,
               StatsContainer stats)

Creates a new MergeOp with the default operation mode and the default timeout used both for readers and the writer

Parameters:

locators - The locators of the inputs that will be merged

stats - Statistics

MergeOp

public MergeOp(URI[] locators,
               OperationMode operationMode,
               StatsContainer stats)

Creates a new MergeOp with configurable operation mode and the default timeout used both for readers and the writer

Parameters:

locators - The locators of the inputs that will be merged

operationMode - The operation mode. One of OperationMode.FIFO and OperationMode.FirstAvailable

stats - Statistics

MergeOp

public MergeOp(URI[] locators,
               OperationMode operationMode,
               long timeout,
               TimeUnit timeUnit,
               StatsContainer stats)

Creates a new MergeOp with configurable operation mode and timeout

Parameters:

locators - The locators of the inputs that will be merged

operationMode - The operation mode. One of OperationMode.FIFO and OperationMode.FirstAvailable

timeout - The timeout that will be used by the RecordWriter and all ForwardReaders

timeUnit - The timeout unit that will be used by the RecordWriter and all ForwardReaders

stats - Statistics

MergeOp

public MergeOp(URI[] locators,
               OperationMode operationMode,
               long timeout,
               TimeUnit timeUnit,
               int bufferCapacity,
               StatsContainer stats)

Creates a new MergeOp with configurable operation mode and timeout

Parameters:

locators - The locators of the inputs that will be merged

operationMode - The operation mode. One of OperationMode.FIFO and OperationMode.FirstAvailable

timeout - The timeout that will be used by the RecordWriter and all ForwardReaders

timeUnit - The timeout unit that will be used by the RecordWriter and all ForwardReaders

bufferCapacity - The capacity of the buffer which will be used by the RecordWriter and all ForwardReaders (if applicable)

stats - Statistics

Method Detail

setRankFieldName

public void setRankFieldName(String rankFieldName)

Sets the name of the field which contains the record rank Used only if operationMode is set to OperationMode.Sort

Parameters:

rankFieldName - The name of the field which contains the record rank

setQuery

public void setQuery(String query)

compute

public URI compute()
            throws Exception

Performs the merging operation

Returns:

The locator of the merged result set

Throws:

Exception - An unrecoverable for the operation error ocurred