com.tangosol.util.aggregator
Class PriorityAggregator

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.BitHelper
          com.tangosol.util.ExternalizableHelper
              com.tangosol.net.AbstractPriorityTask
                  com.tangosol.util.aggregator.PriorityAggregator

All Implemented Interfaces:

ExternalizableLite, PortableObject, PriorityTask, InvocableMap.EntryAggregator, InvocableMap.ParallelAwareAggregator, Serializable

public class PriorityAggregator
extends AbstractPriorityTask
implements InvocableMap.ParallelAwareAggregator, ExternalizableLite, PortableObject

PriorityAggregator is used to explicitly control the scheduling priority and timeouts for execution of EntryAggregator-based methods.

For example, let's assume that there is an Orders cache that belongs to a partitioned cache service configured with a request-timeout and task-timeout of 5 seconds. Also assume that we are willing to wait longer for a particular aggregation request that scans the entire cache. Then we could override the default timeout values by using the PriorityAggregator as follows:

   DoubleAverage      aggrStandard = new DoubleAverage("getPrice");
   PriorityAggregator aggrPriority = new PriorityAggregator(aggrStandard);
   aggrPriority.setExecutionTimeoutMillis(PriorityTask.TIMEOUT_NONE);
   aggrPriority.setRequestTimeoutMillis(PriorityTask.TIMEOUT_NONE);
   cacheOrders.aggregate((Filter) null, aggrPriority);
 

This is an advanced feature which should be used judiciously.

Since:

Coherence 3.3

Author:

gg 2007.03.20

Field Summary

Fields inherited from interface com.tangosol.net.PriorityTask

SCHEDULE_FIRST, SCHEDULE_IMMEDIATE, SCHEDULE_STANDARD, TIMEOUT_DEFAULT, TIMEOUT_NONE

Constructor Summary

PriorityAggregator()
Default constructor (necessary for the ExternalizableLite interface).

PriorityAggregator(InvocableMap.ParallelAwareAggregator aggregator)
Construct a PriorityAggregator.

Method Summary

Object	aggregate(Set setEntries) Process a set of InvocableMap.Entry objects in order to produce an aggregated result.
Object	aggregateResults(Collection collResults) Aggregate the results of the parallel aggregations.
InvocableMap.ParallelAwareAggregator	getAggregator() Obtain the underlying aggregator.
InvocableMap.EntryAggregator	getParallelAggregator() Get an aggregator that can take the place of this aggregator in situations in which the InvocableMap can aggregate in parallel.
void	readExternal(DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
String	toString() Return a human-readable description for this PriorityAggregator.
void	writeExternal(DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Methods inherited from class com.tangosol.net.AbstractPriorityTask

getExecutionTimeoutMillis, getRequestTimeoutMillis, getSchedulingPriority, runCanceled, setExecutionTimeoutMillis, setRequestTimeoutMillis, setSchedulingPriority

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, toBitString, toBitString, toBitString

Constructor Detail

PriorityAggregator

public PriorityAggregator()

Default constructor (necessary for the ExternalizableLite interface).

PriorityAggregator

public PriorityAggregator(InvocableMap.ParallelAwareAggregator aggregator)

Construct a PriorityAggregator.

Parameters:

aggregator - the aggregator wrapped by this PriorityAggregator

Method Detail

getParallelAggregator

public InvocableMap.EntryAggregator getParallelAggregator()

Get an aggregator that can take the place of this aggregator in situations in which the InvocableMap can aggregate in parallel.

Specified by:

getParallelAggregator in interface InvocableMap.ParallelAwareAggregator

Returns:

the aggregator that will be run in parallel

aggregateResults

public Object aggregateResults(Collection collResults)

Aggregate the results of the parallel aggregations.

Specified by:

aggregateResults in interface InvocableMap.ParallelAwareAggregator

Returns:

the aggregation of the parallel aggregation results

aggregate

public Object aggregate(Set setEntries)

Process a set of InvocableMap.Entry objects in order to produce an aggregated result.

Specified by:

aggregate in interface InvocableMap.EntryAggregator

Parameters:

setEntries - a Set of read-only InvocableMap.Entry objects to aggregate

Returns:

the aggregated result from processing the entries

getAggregator

public InvocableMap.ParallelAwareAggregator getAggregator()

Obtain the underlying aggregator.

Returns:

the aggregator wrapped by this PriorityAggregator

toString

public String toString()

Return a human-readable description for this PriorityAggregator.

Returns:

a String description of the PriorityAggregator

readExternal

public void readExternal(DataInput in)
                  throws IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Overrides:

readExternal in class AbstractPriorityTask

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

IOException - if an I/O exception occurs

NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(DataOutput out)
                   throws IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Overrides:

writeExternal in class AbstractPriorityTask

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

The AbstractPriorityTask implementation reserves property indexes 0 - 9.

The PriorityAggregator implementation reserves property index 10.

Specified by:

readExternal in interface PortableObject

Overrides:

readExternal in class AbstractPriorityTask

Parameters:

in - the PofReader from which to read the object's state

Throws:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

The AbstractPriorityTask implementation reserves property indexes 0 - 9.

The PriorityAggregator implementation reserves property index 10.

Specified by:

writeExternal in interface PortableObject

Overrides:

writeExternal in class AbstractPriorityTask

Parameters:

out - the PofWriter to which to write the object's state

Throws:

IOException - if an I/O error occurs