org.jgroups.protocols.pbcast

Class STATE_TRANSFER

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.pbcast.STATE_TRANSFER

All Implemented Interfaces:

ProcessingQueue.Handler<Address>

public class STATE_TRANSFER
extends Protocol
implements ProcessingQueue.Handler<Address>

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 double	avg_state_size
protected boolean	flushProtocolInStack
protected Address	local_addr
protected java.util.List<Address>	members
protected java.util.concurrent.atomic.AtomicLong	num_bytes_sent
protected java.util.concurrent.atomic.AtomicInteger	num_state_reqs
protected long	start
protected ProcessingQueue<Address>	state_requesters List of members requesting state
protected long	stop
protected View	view
protected boolean	waiting_for_state_response set to true while waiting for a STATE_RSP

Fields inherited from class org.jgroups.stack.Protocol

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

Constructor Summary

Constructors

Constructor and Description
STATE_TRANSFER()

Method Summary

Modifier and Type	Method and Description
void	closeBarrierAndSuspendStable()
protected void	closeHoleFor(Address member)
protected Address	determineCoordinator() Return the first element of members which is not me.
java.lang.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)
void	handle(Address state_requester)
protected void	handleException(java.lang.Throwable exception)
protected void	handleStateReq(Address requester)
protected void	handleStateRsp(Digest digest, Address sender, byte[] state) Set the digest and the send the state up to the application
protected void	handleViewChange(View v)
void	init() Called after instance has been created (null constructor) and before protocol is started.
protected boolean	isDigestNeeded() When FLUSH is used we do not need to pass digests between members see JGroups/doc/design/PartialStateTransfer.txt see JGroups/doc/design/FLUSH.txt
void	openBarrier()
void	openBarrierAndResumeStable()
protected void	punchHoleFor(Address member)
java.util.List<java.lang.Integer>	requiredDownServices() List of events that are required to be answered by some layer below
void	resetStats()
void	resumeStable()
protected void	sendException(Address requester, java.lang.Throwable exception)
void	start() This method is called on a Channel.connect(String).
void	stop() This method is called on a Channel.disconnect().
java.lang.Object	up(Event evt) An event was received from the layer below.

Methods inherited from class org.jgroups.stack.Protocol

accept, afterCreationHook, destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, printStats, providedDownServices, providedUpServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled, up

Methods inherited from class java.lang.Object

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

Field Detail

start

protected long start

stop

protected long stop

num_state_reqs

protected final java.util.concurrent.atomic.AtomicInteger num_state_reqs

num_bytes_sent

protected final java.util.concurrent.atomic.AtomicLong num_bytes_sent

avg_state_size

protected double avg_state_size

local_addr

protected Address local_addr

view

protected volatile View view

members

protected final java.util.List<Address> members

state_requesters

protected final ProcessingQueue<Address> state_requesters

List of members requesting state

waiting_for_state_response

protected volatile boolean waiting_for_state_response

set to true while waiting for a STATE_RSP

flushProtocolInStack

protected boolean flushProtocolInStack

Constructor Detail

STATE_TRANSFER

public STATE_TRANSFER()

Method Detail

getNumberOfStateRequests

public int getNumberOfStateRequests()

getNumberOfStateBytesSent

public long getNumberOfStateBytesSent()

getAverageStateSize

public double getAverageStateSize()

requiredDownServices

public java.util.List<java.lang.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

resetStats

public void resetStats()

Overrides:

resetStats in class Protocol

init

public void init()
          throws java.lang.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:

java.lang.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 java.lang.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:

java.lang.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()

openBarrier

public void openBarrier()

resumeStable

public void resumeStable()

up

public java.lang.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 java.lang.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

isDigestNeeded

protected boolean isDigestNeeded()

When FLUSH is used we do not need to pass digests between members see JGroups/doc/design/PartialStateTransfer.txt see JGroups/doc/design/FLUSH.txt

Returns:

true if use of digests is required, false otherwise

punchHoleFor

protected void punchHoleFor(Address member)

closeHoleFor

protected void closeHoleFor(Address member)

determineCoordinator

protected Address determineCoordinator()

Return the first element of members which is not me. Otherwise return null.

handleViewChange

protected void handleViewChange(View v)

handleException

protected void handleException(java.lang.Throwable exception)

handle

public void handle(Address state_requester)

Specified by:

handle in interface ProcessingQueue.Handler<Address>

handleStateReq

protected void handleStateReq(Address requester)

getStateFromApplication

protected void getStateFromApplication(Address requester,
                                       Digest digest)

sendException

protected void sendException(Address requester,
                             java.lang.Throwable exception)

handleStateRsp

protected void handleStateRsp(Digest digest,
                              Address sender,
                              byte[] state)

Set the digest and the send the state up to the application