edu.umass.cs.protocoltask

Class ThresholdProtocolTask<NodeIDType,EventType,KeyType>

java.lang.Object

edu.umass.cs.protocoltask.ThresholdProtocolTask<NodeIDType,EventType,KeyType>

Type Parameters:

NodeIDType -

EventType -

KeyType - This abstract class is concretized for Long keys, int node IDs, and ProtocolPackets. Its purpose is to receive responses from a threshold number of nodes in the specified set. To enable this, instantiators of this abstract class must implement (1) a "boolean handleEvent(event)" method that says whether or not the response was valid, which helps ThresholdProtocolTask automatically stop retrying with nodes that have already responded; (2) a handleThresholdEvent(.) method that returns a protocol task to be executed when the threshold is reached (returning null automatically cancels the task as it is considered complete).

All Implemented Interfaces:

ProtocolTask<NodeIDType,EventType,KeyType>, SchedulableProtocolTask<NodeIDType,EventType,KeyType>, Keyable<KeyType>

Direct Known Subclasses:

MajorityFetchProtocolTask, WaitAckDropEpoch, WaitAckStartEpoch, WaitAckStopEpoch, WaitEpochFinalState

public abstract class ThresholdProtocolTask<NodeIDType,EventType,KeyType>
extends java.lang.Object
implements SchedulableProtocolTask<NodeIDType,EventType,KeyType>

Author:

V. Arun

Field Summary

Fields

Modifier and Type	Field and Description
protected Waitfor<NodeIDType>	waitfor

Constructor Summary

Constructors

Constructor and Description
ThresholdProtocolTask(java.util.Set<NodeIDType> nodes) Set of nodes from which we expect to hear back.
ThresholdProtocolTask(java.util.Set<NodeIDType> nodes, int threshold) Set of nodes out of which we expect to hear back from threshold number of nodes.
ThresholdProtocolTask(java.util.Set<NodeIDType> nodes, int threshold, boolean autoCancel) Set of nodes out of which we expect to hear back from threshold number of nodes.

Method Summary

Modifier and Type	Method and Description
protected GenericMessagingTask<NodeIDType,?>[]	fix(GenericMessagingTask<NodeIDType,?>[] mtasks)
long	getPeriod() The current restart period.
abstract boolean	handleEvent(ProtocolEvent<EventType,KeyType> event)
GenericMessagingTask<NodeIDType,?>[]	handleEvent(ProtocolEvent<EventType,KeyType> event, ProtocolTask<NodeIDType,EventType,KeyType>[] ptasks) This method automatically keeps track of senders from which we have already received valid responses in order to keep track of whether the threshold has been reached, and if so, it invokes handleThresholdEvent
GenericMessagingTask<NodeIDType,?>[]	handleThresholdEvent(ProtocolTask<NodeIDType,EventType,KeyType>[] ptasks) Default action is to cancel the protocol task when the threshold is reached.
void	setPeriod(long restartPeriod)

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.umass.cs.protocoltask.SchedulableProtocolTask

restart

Methods inherited from interface edu.umass.cs.protocoltask.ProtocolTask

getEventTypes, start

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

getKey

Field Detail

waitfor

protected final Waitfor<NodeIDType> waitfor

Constructor Detail

ThresholdProtocolTask

public ThresholdProtocolTask(java.util.Set<NodeIDType> nodes)

Set of nodes from which we expect to hear back.

Parameters:

nodes -

ThresholdProtocolTask

public ThresholdProtocolTask(java.util.Set<NodeIDType> nodes,
                             int threshold)

Set of nodes out of which we expect to hear back from threshold number of nodes.

Parameters:

nodes -

threshold -

ThresholdProtocolTask

public ThresholdProtocolTask(java.util.Set<NodeIDType> nodes,
                             int threshold,
                             boolean autoCancel)

Set of nodes out of which we expect to hear back from threshold number of nodes.

Parameters:

nodes -

threshold -

autoCancel -

Method Detail

handleEvent

public abstract boolean handleEvent(ProtocolEvent<EventType,KeyType> event)

Parameters:

event -

Returns:

Return value indicates if the event is a valid response.

handleThresholdEvent

public GenericMessagingTask<NodeIDType,?>[] handleThresholdEvent(ProtocolTask<NodeIDType,EventType,KeyType>[] ptasks)

Default action is to cancel the protocol task when the threshold is reached.

Parameters:

ptasks -

Returns:

Returns messaging tasks to be performed when the threshold is reached. Additional protocol task actions may also be spawned via ptasks[0].

handleEvent

public final GenericMessagingTask<NodeIDType,?>[] handleEvent(ProtocolEvent<EventType,KeyType> event,
                                                              ProtocolTask<NodeIDType,EventType,KeyType>[] ptasks)

This method automatically keeps track of senders from which we have already received valid responses in order to keep track of whether the threshold has been reached, and if so, it invokes handleThresholdEvent

Specified by:

handleEvent in interface ProtocolTask<NodeIDType,EventType,KeyType>

Returns:

Returns messaging tasks to be performed.

fix

protected GenericMessagingTask<NodeIDType,?>[] fix(GenericMessagingTask<NodeIDType,?>[] mtasks)

setPeriod

public void setPeriod(long restartPeriod)

Parameters:

restartPeriod - The period after which restart messages will be sent (only to nodes from which valid responses have not yet been received).

getPeriod

public long getPeriod()

The current restart period.

Specified by:

getPeriod in interface SchedulableProtocolTask<NodeIDType,EventType,KeyType>

Returns:

The restart period.