org.jgroups.protocols.pbcast

Class STATE_TRANSFER

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.pbcast.STATE_TRANSFER

public class STATE_TRANSFER
extends Protocol

STATE_TRANSFER protocol based on byte array transfer. A state request is sent to a chosen member (coordinator if null). That member makes a copy D of its current digest and asks the application for a copy of its current state S. Then the member returns both S and D to the requester. The requester first sets its digest to D and then returns the state to the application.

Author:

Bela Ban

See Also:

STATE, STATE_SOCK

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	STATE_TRANSFER.StateHeader Wraps data for a state request/response.

Field Summary

Fields

Modifier and Type	Field and Description
protected AtomicBoolean	barrier_closed Used to prevent spurious open and close barrier calls

Fields inherited from class org.jgroups.stack.Protocol

down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
STATE_TRANSFER()

Method Summary

Methods

Modifier and Type	Method and Description
void	closeBarrierAndSuspendStable()
Object	down(Event evt) An event is to be sent down the stack.
double	getAverageStateSize()
long	getNumberOfStateBytesSent()
int	getNumberOfStateRequests()
protected void	getStateFromApplication(Address requester, Digest digest)
protected void	handleException(Throwable exception)
void	init() Called after instance has been created (null constructor) and before protocol is started.
void	openBarrierAndResumeStable()
List<Integer>	requiredDownServices() List of events that are required to be answered by some layer below.
void	resetStats()
protected void	sendException(Address requester, Throwable exception)
void	start() This method is called on a Channel.connect(String).
void	stop() This method is called on a Channel.disconnect().
Object	up(Event evt) An event was received from the layer below.

Methods inherited from class org.jgroups.stack.Protocol

destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedDownServices, providedUpServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled

Methods inherited from class java.lang.Object

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

Field Detail

barrier_closed

protected AtomicBoolean barrier_closed

Used to prevent spurious open and close barrier calls

Constructor Detail

STATE_TRANSFER

public STATE_TRANSFER()

Method Detail

getNumberOfStateRequests

public int getNumberOfStateRequests()

getNumberOfStateBytesSent

public long getNumberOfStateBytesSent()

getAverageStateSize

public double getAverageStateSize()

requiredDownServices

public List<Integer> requiredDownServices()

Description copied from class: Protocol

List of events that are required to be answered by some layer below.

Overrides:

requiredDownServices in class Protocol

Returns:

Vector (of Integers)

resetStats

public void resetStats()

Overrides:

resetStats in class Protocol

init

public void init()
          throws Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Protocol

Throws:

Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

start

public void start()
           throws Exception

Description copied from class: Protocol

This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.

Overrides:

start in class Protocol

Throws:

Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception

stop

public void stop()

Description copied from class: Protocol

This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

Overrides:

stop in class Protocol

closeBarrierAndSuspendStable

public void closeBarrierAndSuspendStable()

openBarrierAndResumeStable

public void openBarrierAndResumeStable()

up

public Object up(Event evt)

Description copied from class: Protocol

An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().

Overrides:

up in class Protocol

down

public Object down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().

Overrides:

down in class Protocol

handleException

protected void handleException(Throwable exception)

getStateFromApplication

protected void getStateFromApplication(Address requester,
                           Digest digest)

sendException

protected void sendException(Address requester,
                 Throwable exception)