org.infinispan.commands.read

Class ReduceCommand<KOut,VOut>

java.lang.Object

org.infinispan.commands.remote.BaseRpcCommand

org.infinispan.commands.read.ReduceCommand<KOut,VOut>

All Implemented Interfaces:

CancellableCommand, CacheRpcCommand, ReplicableCommand

public class ReduceCommand<KOut,VOut>
extends BaseRpcCommand
implements CancellableCommand

ReduceCommand is a container to migrate Reducer to a remote Infinispan node where it will get executed and return the result to an invoking/master node.

Since:

5.2

Author:

Vladimir Blagojevic

Field Summary

Fields

Modifier and Type	Field and Description
static int	COMMAND_ID

Fields inherited from class org.infinispan.commands.remote.BaseRpcCommand

cacheName

Constructor Summary

Constructors

Constructor and Description
ReduceCommand(String cacheName)
ReduceCommand(String taskId, Reducer<KOut,VOut> reducer, String cacheName, Collection<KOut> inputKeys)

Method Summary

Modifier and Type	Method and Description
boolean	canBlock() If true, the command is processed asynchronously in a thread provided by an Infinispan thread pool.
boolean	emitsIntoResultingCache()
boolean	equals(Object obj)
byte	getCommandId() Used by marshallers to convert this command into an id for streaming.
Set<KOut>	getKeys()
Reducer<KOut,VOut>	getReducer()
String	getResultCacheName()
String	getTaskId()
UUID	getUUID() Returns UUID of a command
int	hashCode()
void	init(MapReduceManager mrManager)
boolean	isReturnValueExpected() If true, a return value will be provided when performed remotely.
boolean	isUseIntermediateSharedCache()
Object	perform(InvocationContext context) Performs invocation of reduce phase on assigned Infinispan node
void	readFrom(ObjectInput input) Reads this instance from the stream written by ReplicableCommand.writeTo(ObjectOutput).
void	setResultCacheName(String resultCacheName)
void	setUseIntermediateSharedCache(boolean useIntermediateSharedCache)
String	toString()
void	writeTo(ObjectOutput output) Writes this instance to the ObjectOutput.

Methods inherited from class org.infinispan.commands.remote.BaseRpcCommand

getCacheName, getOrigin, setOrigin

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.infinispan.commands.remote.CacheRpcCommand

getCacheName, getOrigin, setOrigin

Methods inherited from interface org.infinispan.commands.ReplicableCommand

getParameters, setParameters

Field Detail

COMMAND_ID

public static final int COMMAND_ID

See Also:

Constant Field Values

Constructor Detail

ReduceCommand

public ReduceCommand(String cacheName)

ReduceCommand

public ReduceCommand(String taskId,
                     Reducer<KOut,VOut> reducer,
                     String cacheName,
                     Collection<KOut> inputKeys)

Method Detail

init

public void init(MapReduceManager mrManager)

perform

public Object perform(InvocationContext context)
               throws Throwable

Performs invocation of reduce phase on assigned Infinispan node

Specified by:

perform in interface ReplicableCommand

Parameters:

context - invocation context

Returns:

Map of intermediate key value pairs

Throws:

Throwable - in the event of problems.

isUseIntermediateSharedCache

public boolean isUseIntermediateSharedCache()

setUseIntermediateSharedCache

public void setUseIntermediateSharedCache(boolean useIntermediateSharedCache)

emitsIntoResultingCache

public boolean emitsIntoResultingCache()

getResultCacheName

public String getResultCacheName()

setResultCacheName

public void setResultCacheName(String resultCacheName)

getKeys

public Set<KOut> getKeys()

getReducer

public Reducer<KOut,VOut> getReducer()

getTaskId

public String getTaskId()

getCommandId

public byte getCommandId()

Description copied from interface: ReplicableCommand

Used by marshallers to convert this command into an id for streaming.

Specified by:

getCommandId in interface ReplicableCommand

Returns:

the method id of this command. This is compatible with pre-2.2.0 MethodCall ids.

getUUID

public UUID getUUID()

Description copied from interface: CancellableCommand

Returns UUID of a command

Specified by:

getUUID in interface CancellableCommand

Returns:

command UUID

writeTo

public void writeTo(ObjectOutput output)
             throws IOException

Description copied from interface: ReplicableCommand

Writes this instance to the ObjectOutput.

Specified by:

writeTo in interface ReplicableCommand

Parameters:

output - the stream.

Throws:

IOException - if an error occurred during the I/O.

readFrom

public void readFrom(ObjectInput input)
              throws IOException,
                     ClassNotFoundException

Description copied from interface: ReplicableCommand

Reads this instance from the stream written by ReplicableCommand.writeTo(ObjectOutput).

Specified by:

readFrom in interface ReplicableCommand

Parameters:

input - the stream to read.

Throws:

IOException - if an error occurred during the I/O.

ClassNotFoundException - if it tries to load an undefined class.

isReturnValueExpected

public boolean isReturnValueExpected()

Description copied from interface: ReplicableCommand

If true, a return value will be provided when performed remotely. Otherwise, a remote ResponseGenerator may choose to simply return null to save on marshalling costs.

Specified by:

isReturnValueExpected in interface ReplicableCommand

Returns:

true or false

canBlock

public boolean canBlock()

Description copied from interface: ReplicableCommand

If true, the command is processed asynchronously in a thread provided by an Infinispan thread pool. Otherwise, the command is processed directly in the JGroups thread.

This feature allows to avoid keep a JGroups thread busy that can originate discard of messages and retransmissions. So, the commands that can block (waiting for some state, acquiring locks, etc.) should return true.

Specified by:

canBlock in interface ReplicableCommand

Overrides:

canBlock in class BaseRpcCommand

Returns:

true if the command can block/wait, false otherwise

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class BaseRpcCommand