edu.umass.cs.reconfiguration.reconfigurationpackets

Class DefaultAppRequest

java.lang.Object

edu.umass.cs.reconfiguration.reconfigurationpackets.DefaultAppRequest

All Implemented Interfaces:

Request, RequestIdentifier, ReconfigurableRequest, ReplicableRequest, Summarizable

public class DefaultAppRequest
extends java.lang.Object
implements ReplicableRequest, ReconfigurableRequest

Author:

V. Arun This request is unlike usual requests that can be converted to a String and back. This request is not meant to be serialized and sent over the network, but only passed internally within a single node.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	DefaultAppRequest.Keys

Field Summary

Fields inherited from interface edu.umass.cs.reconfiguration.interfaces.ReconfigurableRequest

STOP

Fields inherited from interface edu.umass.cs.gigapaxos.interfaces.Request

NO_OP

Constructor Summary

Constructors

Constructor and Description
DefaultAppRequest(org.json.JSONObject json)
DefaultAppRequest(java.lang.String serviceName, int epochNumber, boolean stop)

Method Summary

Modifier and Type	Method and Description
int	getEpochNumber()
long	getRequestID() The uniqueness of this identifier across all requests to a replica group is important for safety when PaxosConfig.PC.PREVENT_DOUBLE_EXECUTION is enabled as gigapaxos may otherwise assume that the duplicate request identifier corresponds to a retransmission and will send back the response if any corresponding to the first execution.
IntegerPacketType	getRequestType()
java.lang.String	getServiceName()
boolean	isStop()
boolean	needsCoordination()
void	setNeedsCoordination(boolean b) After this method returns, ReplicableRequest.needsCoordination() should subsequently return b.
org.json.JSONObject	toJSONObject()
java.lang.String	toString() Serializes the request to a String.

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.umass.cs.reconfiguration.interfaces.ReconfigurableRequest

getSummary

Methods inherited from interface edu.umass.cs.gigapaxos.interfaces.Request

toBytes

Methods inherited from interface edu.umass.cs.utils.Summarizable

getSummary

Constructor Detail

DefaultAppRequest

public DefaultAppRequest(java.lang.String serviceName,
                         int epochNumber,
                         boolean stop)

Parameters:

serviceName -

epochNumber -

stop -

DefaultAppRequest

public DefaultAppRequest(org.json.JSONObject json)
                  throws org.json.JSONException

Parameters:

json -

Throws:

org.json.JSONException

Method Detail

getRequestType

public IntegerPacketType getRequestType()

Specified by:

getRequestType in interface Request

Returns:

The IntegerPacketType type corresponding to this request.

getServiceName

public java.lang.String getServiceName()

Specified by:

getServiceName in interface Request

Returns:

Returns the unique app-level replica-group ID.

toString

public java.lang.String toString()

Description copied from interface: Request

Serializes the request to a String. The default toString() method must be overridden.

Specified by:

toString in interface Request

Overrides:

toString in class java.lang.Object

Returns:

Returns this request serialized as a String.

toJSONObject

public org.json.JSONObject toJSONObject()
                                 throws org.json.JSONException

Returns:

JSONObject corresponding to this request.

Throws:

org.json.JSONException

getEpochNumber

public int getEpochNumber()

Specified by:

getEpochNumber in interface ReconfigurableRequest

Returns:

The epoch number.

isStop

public boolean isStop()

Specified by:

isStop in interface ReconfigurableRequest

Returns:

True if this request is a stop request.

needsCoordination

public boolean needsCoordination()

Specified by:

needsCoordination in interface ReplicableRequest

Returns:

True if this request needs to be coordinated, false otherwise.

setNeedsCoordination

public void setNeedsCoordination(boolean b)

Description copied from interface: ReplicableRequest

After this method returns, ReplicableRequest.needsCoordination() should subsequently return b. This method is invoked by AbstractReplicaCoordinator with a false argument just before coordinating the request so that coordinated packets are not coordinated again infinitely. For example, if a replica coordinator's coordination strategy is to simply flood the request to all replicas, there needs to be a way for a recipient of a copy of this already once coordinated request to know that it should not coordinate it again. This method provides AbstractReplicaCoordinator a placeholder in the application request to prevent such infinite coordination loops.

This method is now deprecated and does not need to be overridden by implementing classes. It's original purpose was really only to be able to easily do lazy propagation replica coordination without introducing an additional type (just to distinguish between the original request at the entry replica and the replicated request so as to avoid an infinite propagation loop), but introducing an additional type is the clean way to do this. Paxos for example already has its own types, so it doesn't need this method.

Specified by:

setNeedsCoordination in interface ReplicableRequest

Parameters:

b - True if subsequent invocations of ReplicableRequest.needsCoordination() must return true, false otherwise.

getRequestID

public long getRequestID()

Description copied from interface: RequestIdentifier

The uniqueness of this identifier across all requests to a replica group is important for safety when PaxosConfig.PC.PREVENT_DOUBLE_EXECUTION is enabled as gigapaxos may otherwise assume that the duplicate request identifier corresponds to a retransmission and will send back the response if any corresponding to the first execution. With PaxosConfig.PC.PREVENT_DOUBLE_EXECUTION disabled, the uniqueness is important for liveness as duplicate request identifiers may result in the client not receiving a response for the latter request; this is because gigapaxos stores request execution callbacks indexed by the request identifier, so there must be at most one outstanding request with a given identifier for a given replica group.

Specified by:

getRequestID in interface RequestIdentifier

Returns:

A unique request identifier for this request.